Is C2H4 Polar or Nonpolar?

Answer: C2H4 is a nonpolar molecule due to the exclusive occurrence of nonpolar covalent C-H bonds. The different outer hydrogen atoms are also arranged symmetrical around two central carbon atoms balancing out any de minimis electronegativity differences. 

Due to the simple nonpolar nature of Ethylene, the structure has a melting point of -169˚C and a boiling point of -104˚C. This makes the structure a gas at standard temperature and pressure. It is said to have a "sweet and musky" odor although the gas is flammable due to the large amount of energy stored within the carbon double-bond. Furthermore, it takes a large amount of energy in order to rotate the molecule due to the pi bond within the double bond, making the final structure quite rigid. In terms of final products, the carbons in ethylene are utilized in order to build many different types of plastics, most notably polyethylene. It can also be found in a multitude of other reactions to form different carbon-based molecules.

C2H4 Ball and Stick Model
C2H4 Ball and Stick Model. Created with MolView.
How is ethylene utilized in plant systems?

Although C2H4 is utilized in certain specific industrial applications, it is primarily noted as an important compound within plant systems. The molecule is utilized as a signaling molecule in order to ripen fruit, open flowers and shedding leaves. As a result this has been utilized in commercial applications in order to produce fruit faster in agriculture. This application has a quite storied history going all the way back to the Ancient Egyptians.

Is NH4+ Polar or Nonpolar?

Answer: NH4+ is a "nonpolar" molecule according to its tetrahedral structure since all of the hydrogen atoms are arranged symmetrically around the central nitrogen atom. However the molecule has more polar characteristics since it an ion with one electron missing from its central nitrogen atom. 

Ammonium is formed by the addition a hydrogen atom to ammonia (NH3). This forms a positive cation with a +1 charge on the nitrogen atom. As a result, NH4+ is weakly acidic, wishing to exchange a hydrogen with a lone pair of electrons to achieve a neutral charge. Ammonium is also capable of forming a wide variety of salts. However, some of these are noted to be quite explosive.

To learn more about the polarity and lewis dot structure of NH3, feel free to check out this article and this brief, respectively.

NH4+ Ball and Stick Model
NH4+ Ball and Stick Model. Created with MolView.
What is the role of ammonium in biological systems?

One of the most recognizable functional groups within biology amine group (NH, NH2 or NH3). This is an important feature of amino acids, allowing primary structures to form. Moreover, ammonium ions are a byproduct of metabolism within the human body. While many species convert this product to urea for disposal, there are certain fish that release it directly into the surrounding water. NH4+ is also an important nitrogen source for plants; however, it is toxic at high concentrations and therefore cannot be relied upon solely.

Is PCl5 Polar or Nonpolar?

Answer: PCl5 is a nonpolar molecule since the electron pull balances it out in both the horizontal and vertical axis of the molecule. In one of these there is a linear structure and in the other there is a trigonal structure which both result in no permanent dipoles. 

Although the molecule has no dipole moment, the large amount of electrons throughout the chlorines and affinity for electrons lead the molecule to form strong temporary forces, permitting a melting point of 161˚C and a boiling point of 167˚C. As a result the molecule is a solid at standard temperature and pressure. In certain related polar solvents (typically those that themselves contain a lot of chlorine molecules) the molecule is undergo ionization by either releasing or gaining chlorine atoms. The structure shown below typically holds for the liquid and gas phases of the molecule while a more "ionic-type" compound is more present in the solid form with the cation transferring a chlorine completely to the anion and thereby binding with itself. Due to the large number of chlorines, phosphorus pentachloride is typically utilized in order to add chlorines to other molecules in reaction chains. Due to the large affinity of chlorine for electrons (electronegativity: 3.16), the molecule behaves as an acid.

PCl5 Ball and Stick Model
PCl5 Ball and Stick Model. Created with MolView.

Although PCl5 is sold commercially and oftentimes is contaminated with HCl in these contexts (you can theoretically tell whether this is the case by the color - yellow means that the compound has been contaminated since the substance is supposed to be colorless), phosphorus pentachloride is an incredibly dangerous substance, reacting violently with water, being corrosive to human skin and toxic when inhaled. This is mostly due to the affinity of chlorines for electrons.

Is PF3 Polar or Nonpolar?

Answer: PF3 is a polar molecule due to the presence of a lone pair of electrons resulting in a bent structure due to electron-electron repulsion. This leads to an unequal distribution of charge within the molecule. 

In a similar fashion to when we discussed other molecules containing lots of fluorine, the presence of such an electronegative element (3.98) vs. phosphorus (2.19) dents to impact of the lone pair electron dipole since charge is a little more evenly spread throughout the molecule. As a result phosphorus trifluoride has a melting point of -152˚C and a boiling point of -102˚C. This makes the molecule a gas at standard temperature and pressure. The structure reacts relatively slowly with water (i.e. in terms of solubility) due to the lower dipole moment.

PF3 Ball and Stick Model
PF3 Ball and Stick Model. Created with MolView.
Why is PF3 highly toxic? 

Similar to when we discussed the polarity of Carbon Monoxide, we noted the biological properties of the molecule at hand. In that case, CO disrupted the hemoglobin function by binding to iron and therefore disrupting the flow of oxygen. This made the gas toxic at concentrations greater than 35 ppm. PF3 performs a similar kind of binding to iron within hemoglobin and therefore it also toxic to human health. In fact, PF3 has an affinity to bind to many of the different transition metals besides iron.

Is BH3 Polar or Nonpolar?

Answer: BH3 is a nonpolar molecule due to the symmetrical trigonal arrangement of the hydrogen atoms around the central boron atom. Furthermore, the low electronegativity difference between boron (2.04) and hydrogen (2.20) means that the molecule contains no polar covalent bonds, thereby negating the possibility of any permanent partial dipoles within the structure. 

BH3, also known as Borane, is primarily characterized by the presence of an incomplete octet. This means that the central Boron atom does not have a complete octet of valence of electrons. As a result the molecule has a high affinity for electrons and is a strong acid. Due to these properties the molecule is highly unstable and reactive although it can be observed for brief periods of time in nature. The structure appears as a transition molecule in certain specific longer reactions; however it does not appear stably in a pure form in nature.

BH3 Ball and Stick Model
BH3 Ball and Stick Model. Created with MolView.
Have other forms of this molecule also been observed?

Although this form is not the exact same molecule as BH3, BH5 is a closely related species of borane. Instead of their being an incomplete octet, BH5 has an expanded octet which is traditionally considered to be impossible for elements in the first three rows of the periodic table. Therefore it makes sense that this molecule has only been observed stably at very low temperatures since it is incredibly unstable and even the slightest energy input from the atmosphere is enough to destroy it.

Is Br2 Polar or Nonpolar?

Answer: Br2 is a nonpolar molecule due to the linear arrangement of identical atoms (i.e. which therefore have the same electronegativity). No permanent dipole can be produced. 

Due to the large number of electrons within Bromine the molecule forms strong temporary forces (also known as London Dispersion Forces) that result in a high melting point of -7.2˚C and boiling point of 58.8˚C. This means that Br2 is a liquid at standard temperature and pressure. Due to the attraction of bromine as a halogen to free electrons, the structure is extremely rare in nature and extremely reactive. As a result, the molecule is not safe to handle and can easily cause burns/scars/worse effects if in direct contact with human skin. As a result, many countries and organizations have a limit for exposure with the compound. Br2 is the precursor for many molecules that include bromine including the acidic form HBr.

Br2 Ball and Stick Model
Br2 Ball and Stick Model. Created with MolView.
How is Bromine utilized in the real world?

The most significant use of the molecule is within flame retardants since it is able to perform similar reactions as what is driving the fire but in fact in a less reactive fashion. Furthermore, bromine was added to engine fuel in order to remove "knocking" and added as a pesticide in agricultural applications. However both of these uses were ended when it was discovered that free bromine helped to disintegrate the ozone layer within the atmosphere. Bromine salts find some uses in pharmacology and water treatment. These salts combine a bromine atom with an alkali metal.

Are Lipids Polar or Nonpolar?

Answer: Lipids are typically nonpolar due to the large number of nonpolar covalent carbon-carbon (C-C) and carbon-hydrogen (C-H) bonds present within the molecule. These result in structures that exemplify nonpolar characteristics even though they may contain one or two groups that are polar by themselves. 

As the diagram below indicates, there are a few different types of lipids including cholesterol, fatty acids, triglycerides and phospholipids. There are also different kinds of waxes and vitamins that are classified as lipids. The specific naming and classification scheme for different lipids depends on the specific configuration of the chemical bonds within the lipid. Some lipids (ex. phospholipids) have a hydrophobic tail and hydrophilic head. This allows one part of the molecular to be nonpolar (tail) and another to be polar (head). This allows for the formation of lipid bilayers - a similar property present in soap. However, lipids typically only refer to nonpolar molecules in biology.

Different Kinds of Lipids
Different kinds of lipids and their structural formulas. Source 
What purpose do lipids serve within biological contexts?

There are a wide range of functions associated with lipids. As hinted at earlier, phospholipids form the bilayer that separates the internal cell environment from the outer environment and permits organelles in eukaryotic cells to compartmentalize functions and create special environments within the cell. Furthermore, hormone lipids and vitamins play an important role in cell signaling and transduction cascades. For example, metabolism, reproduction and blood pressure regulation mechanisms involve different hormones. Lastly, the most recognizable use of lipids is for energy storage in the form of fats. This is effective because fatty acid triglycerides can store a large amount of energy within small cell vesicles.

Is BrF3 Polar or Nonpolar?

Answer: BrF3 is a polar molecule due to the presence of two pairs of lone pair electrons. These because of electron-electron repulsion cause a bent structure. This results in an unequal distribution of charge and the creation of a permanent dipole. 

Due to the combination of polar permanent partial charges and temporary charges caused by the unequal distribution of electrons, this molecule has a melting point of 8.8˚C and a boiling point of 126˚C. Although you would expect this molecule since it is polar to dissolve in water, Bromide trifluoride in fact only dissolves in sulfuric acid since sulfuric acid is strong enough to prevent BrF3 from decomposing into other acids. For example the structure reacts with water to form both hydrogen fluoride and hydrogen bromide, both strong acids in their own right. BrF3 is a liquid at standard temperature and pressure.

If you are interested in learning about the related molecule ClF3, feel free to check out this article.

BrF3 Ball and Stick Model
BrF3 Ball and Stick Model. Created with MolView.
How is BrF3 utilized in the real world?

Similar to ClF3, Bromine trifluoride is utilized as a powerful fluorinating agent, adding fluorides to certain compounds within reactions. It is specifically utilized in the reaction to create UF6 for nuclear fuel processing. Furthermore, it can also be utilized as a conductor because it self-ionizes in solution.

Is H3O+ Polar or Nonpolar?

Answer: H3O+ is a polar molecule due to the existence of a pair of lone pair electrons on top of the molecule causing electron-electron repulsion. This results in a "bent" structure that leads to an unequal distribution of charge within the molecule. Furthermore, the positive charge on the oxygen causes this molecule to be a cation which therefore automatically exhibits polar qualities. 

Hydronium is the actual product that forms when people imagine H+ protons within the context of an acid. Individual protons are exceedingly rare, oftentimes H3O+ is formed instead. The transfer of H+ to H2O to form hydronium is what lowers the pH within solution and thereby increases its acidity. All acids are in some sense measured based on their strength relative to hydronium because strong acids are essentially better proton donors and weak acids worse proton donors within solution. According to the international naming conventions, H3O+ is actually supposed to be referred to as oxonium although this is not commonly practiced. 

H3O+ Ball and Stick Diagram
H3O+ Ball and Stick Diagram. Created with MolView.
Besides as an acid in H2O, how else does H3O+ appear?

There is a possibility for H3O+ to combine with negative ions. However, in order for these kinds of compounds to be stable, you will need to make sure your are utilizing a very strong acid. These kinds of salts also form with other combinations of hydrogen and oxygen atoms (such as H5O2). H3O+ also naturally appears in interstellar clouds as the result of reactions turning H2 to H2+ before combining with hydroxide (OH-) atoms. This is a quite interesting observation since the purpose to help ensure that space is ion-neutral.

Is CBr4 Polar or Nonpolar?

Answer: CBr4 is a nonpolar molecule due to the symmetrical arrangement of bromine atoms around a central carbon atom. This cancels out all of the polar electron pulls between the different molecules and therefore no permanent dipole is established. 

Although CBr4 is a nonpolar substance, the fact that each bromine atom contributes 35 electrons increases the capacity for temporary forces caused by the random dispersion of electrons. As a result the molecule actually a quite high melting point of 95˚C and a boiling point of 190˚C. The electronegativity difference between bromine (2.96) and carbon (2.55) contributes to the capacity of this molecule to dissolve in slightly polar solvents like ethanol. The molecule is also known as carbon tetrabromide.

CBr4 Ball and Stick Model
CBr4 Ball and Stick Model. Created with MolView.
How is CBr4 utilized in the real world?

Carbon tetrabromide can be utilized in a variety of reactions in order to add bromine atoms to different hydrocarbons; however, the molecule is less stable than HBr or Br2 when utilized in a chemical reaction. It can also be a solvent itself for a wide variety of waxes and oils. Since CBr4 is non-flammable it is utilized in fire retardants. Furthermore, due to the density of the crystal compound as a result of its tetrahedral structure and electron mass, the compound can be utilized in order to separate minerals from one another (a kind of very fine "filter paper"). 

Is NO2+ Polar or Nonpolar?

Answer: NO2+ is a nonpolar molecule because of its linear structure which cancels out opposing dipole forces. This results in a molecule that does not have permanent partial charges. 

This is also called the Nitronium ion not to be confused with the nitrite ion (or NO2-) which does not have a linear structure. It is a cation similar to ammonium (NH4+) in regards to its charge. This +1 means that the molecule has a high affinity for electrons. In fact, there have been recorded instances where the molecule added in an extra electron to produce a stable compound. While NO2+ can be produced and thereafter exist stably in normal conditions, it is quite reactive on its own merit. Like NH4+, nitronium can form a few different types of salts and molecular compounds where the positive cation is balanced out by a very electronegative or anion species that thereby balances charge across the entire molecule.

NO2+ Ball and Stick Model
NO2+ Ball and Stick Model. Created with Avagadro.
What is the most common usage of NO2+?

Within industrial and laboratory settings NO2+ is most like to be utilized in the nitration of other substances (i.e. the addition of nitronium to a molecule). For example, this article goes through the necessary chemical reactions in order to add NO2 to a benzene ring: 

Is HF Polar or Nonpolar?

Answer: HF is a polar molecule due to the large electronegativity difference between hydrogen (2.20) and fluorine (3.98). This results in a partial negative charge on the latter and a partial positive charge on the former. This molecule has one of the strongest known permanent dipoles and is capable of hydrogen bonding. 

Due to HF having the greatest electronegativity difference between its two atomic components, the hydrogen bonds it forms have the greatest strength. Therefore, HF has a melting point of -84˚C and a boiling point of 20˚C. However, as you may notice, HF does not have a boiling point as high as H2O (where the melting point and boiling point are 0˚C and 100˚C, respectively). This is because HF is only capable of forming one hydrogen bond per molecule whereas H2O can form two hydrogen bonds per molecule (two hydrogens and two lone pairs). Although the hydrogen bonds formed by H2O (water) are individually weaker, together they form intermolecular forces stronger than those found in HF. However, it is the principle source of fluorine an extremely electronegative element. The molecule is also a very dangerous gas, forming hydrofluoric acid when it has contact with water. In fact, the gas can rapidly destroy critical parts of the human eye and thereby cause blindness.

HF Ball and Stick Model
HF Ball and Stick Model. Created with MolView.
How is HF utilized in the real world?

As has been alluded to earlier, HF is a source of fluorine both in its natural form and as it appears in more complex molecules such as fluorocarbons. HF participates in other reactions with various species in order to form these more complex molecules. In certain industries HF can be utilized as a "superacid" or a catalyst for specific reactions to produce certain kinds of pharmaceuticals or polymers. HF is similarly to H2O an excellent solvent of many types of polar molecules. However it is not utilized in practice due to the great danger posed by the molecule to human health if not handled properly. 

Is NaCl Polar or Nonpolar?

Answer: NaCl is a polar molecule due to the large electronegativity difference between sodium (.93) and chlorine (3.16). In fact, the difference is so great that this is considered an ionic bond with the two pieces nearly equivalent to ions. This causes the molecule to bond with itself in very strong crystal lattice conformations. 

Due to these extremely strong bonds, the molecule has a melting point and boiling point of 801˚C and 1405˚C, respectively. These are much larger than the boiling points present in other intermolecular forces such as hydrogen bonding (as seen in H2O). Therefore it is no surprise that the compound forms a crystal lattice solid at standard pressure and temperature. Within this lattice structure sodiums and chlorines alternate between molecules so that attractions can be both in the ionic bond and across the large electronegativity difference b/t different molecules. In fact, chlorines attraction to sodium's one valence electron is so strong that the molecule disassociates in water into Na+ and Cl-. These ions float around within polar substances independently and indeed are typically not very reactive. In fact, when you simply throw in regular sodium or other alkali metals into these environments, the reactions are typically very violent. The sequence of animations at the end of the presentation at the link in the previous sentence illustrates this principle extremely well.

NaCl Ball and Stick Diagram
NaCl Ball and Stick Diagram. Created with MolView
How is NaCl (sodium chloride) utilized in the real world?

The first major place many will recognize NaCl is as the constituent of table salt which adorns many dining tables around the world. In fact the salt shards are at their core simply lattices of NaCl. Sodium chloride determines the salinity within the ocean water and thereby regulates the extracellular environment of many multicellular organisms. Some have become tolerant to high levels of salinity and other organisms actively expend energy to push this salt against its gradient. Salt also helps to add friction and de-ice the roads during major winter weather storms. NaCl also finds use in the production of many other salts/chemicals for industrial applications.

Is SCN Polar or Nonpolar?

Answer: SCN- is a polar molecule due to the difference in electronegativity between nitrogen (3.04), carbon (2.55) and sulfur (2.58). Partial negative charges will be found closer to nitrogen as it pulls electrons from the other part of the structure containing carbon and sulfur. 

Due to the negative charge on the nitrogen atom, the molecule typically acts more as a "base" in that it is more likely to adopt a hydrogen atom. Being an ion, SCN- commonly forms a wide variety of salts with different alkali metals (such as sodium, potassium) and alkali earth metals (magnesium, calcium). Since there is a relatively small difference in electronegativity between nitrogen and sulfur the molecule is able to donate electrons within a reaction from either end of the molecule. SCN- is also known as Thiocyanate. The molecule is often formed by the addition of Sulfur with Cyanide. 

SCN Ball and Stick Model
SCN Ball and Stick Model. Created with Avagadro.
What is the important role of SCN- within the human body?

SCN- is one of the building blocks of many factors that serve antibacterial functions within the body. These factors have been discovered in many natural defense mechanisms including mucous, saliva and tears. This has been related to the symptoms associated with cystic fibrosis. SCN- inhibits iodine transport into thyroid cells so it is recommended that people who are iodine-deficient avoid foods containing thiocyanate. Once upon a time it was utilized in the treatment of hypertension but it has been since replaced in such function by a closely related molecule. 

Is O3 Polar or Nonpolar?

Answer: O3 is a polar molecule due to the presence of lone pair electrons on the central oxygen atom. This due to electron-electron repulsion forces the molecule into a bent structure. This results in an unequal distribution of charge throughout the molecule. 

Due to the presence of a weak polar dipole since all the atoms are identical, O3 also known as ozone has a melting point of -192˚C and a boiling point of -112˚C which is relatively higher than related molecules such as O2 (oxygen). Ozone has been described as a "pale blue" gas at standard temperature and pressure with a distinctive odor. Due to the large number of electronegative (3.44) oxygen's present in the molecule, it often serves as oxidizing agent readily removing electrons from substances/compounds. Ozone is therefore a very unstable molecule and readily decomposes at lower levels of the atmosphere into O2 (oxygen). It is typically formed by the input of UV radiation and short electrical bursts within the upper atmosphere.

To learn more about the closely related Lewis Structure for O2, feel free to check out this article.

O3 Ball and Stick Model
O3 Ball and Stick Model. Created with Avagadro.
How is O3 utilized in the real world?

Within the atmosphere where it exists naturally as described above O3 serves to absorb much of the UV radiation that reaches earth. This mitigates the effects of light rays that would alternatively cause skin and DNA damage for human cells. Certain compounds such as chlorofluorocarbons, molecules containing the halogens fluorine and chlorine along with carbon, create the kinds of "free radicals" necessary to convert O3 back into O2 in the upper atmosphere. This in turn degrades the ozone layer and leaves life exposed to the dangerous effects of the higher-energy UV rays. Ozone is also utilized for wastewater treatment and other types of deep cleaning since it has a capacity to interfere with carbon-carbon bonds. This makes it useful in destroying certain organic life. In fact, human exposure to ozone can also have dangerous effects. Low-level ozone production often goes hand-in-hand with the different pollutants that are components of smog. Urban areas general suffer from more ozone pollution due to the increase of human activity in those regions.

Create a Deck Shuffler in Scratch

Welcome back! In this tutorial we will be creating a deck shuffler and visualizing the shuffled deck. You may notice that the deck within the costumes is in random order in the graphical template but whether or not the deck is ordered at the start does not affect the shuffling. The interface has a dual-fit screen one to visualize the card product on the right and one to visualize the numerical representation of what is going on/how the shuffling is occurring on the left.

Objective: To learn about the list datatype, important features of lists, and the temporary SWAP variable.

Final Product (one whole deck shuffling):

Graphical Template: Link


Deck Shuffling Scratch Scripts
Deck Shuffling Scripts
Focus: See if you can understand the function of the different individual pieces of code What is the purpose of "visualize deck" broadcasting statement? the first repeat 52 block? the repeat 1000 block? What happens if you were to change the repeat 1000 to another number? What do you expect will happen to the deck if the number of very low? very high?

Completed Project: Link

Is XeF2 Polar or Nonpolar?

Answer: XeF2 is a nonpolar molecule due to the linear arrangement of the fluorine atoms around the central xenon atom. This results in the different pulls on the electrons of the central atom cancelling out and therefore there is no permanent dipole. 

Although this may seem counterintuitive since the central xenon atom has three lone pair of electrons, it is important to consider that those lone pairs are actually arranged in a trigonal planar orientation around the molecule. Please take a look at PF5 to see this trigonal planar + linear pattern visualized with fluorine atoms. In essence here we only have two fluorine atoms and the lone pairs replace the trigonal planar arrangement.

Therefore when you cut the "xenon" plane in half you find two lone pairs either above or below the plane and then the one remaining lone pair either above/below the plane depending on where the first two lone pairs appeared. The difference in these charges allow for XeF2 to form a crystal - matching up regions with two lone pairs with the corresponding region with one lone pair on another XeF2 atom. This crystal lattice is strengthened by the capacity for more powerful temporary bonds due to the large number of electrons within the structure (xenon itself has 54 electrons!).

However, due to the natural stability of noble gases, the molecule is very sensitive to energy input. Although it is stable in storage, any exposure to sunlight or moisture quickly decomposes the molecule. Within storage as mentioned before it forms a white brilliant crystalline solid.

XeF2 Ball and Stick Structure
XeF2 Ball and Stick Structure. Created with MolView.
How is XeF2 utilized in the real world? 

Due to the presence of fluorines and the capacity for XeF2 to give up those fluorines, it is often utilized as a chemical agent to add fluorines to a certain compound/molecule. It can also be utilized to manipulate/design tough silicon systems through the release of fluorine in order to manufacture specific electrical components.

Is Acetone Polar or Nonpolar?

Answer: Acetone is a polar molecule due to the existence of a very electronegative oxygen (3.44) in the center of the molecule. This oxygen pulls electrons from the central carbon and other R- groups with lower electronegativity (2.55) and creates a partial negative charge. This leaves the other parts of the molecule with a partial positive charge.  

Acetone is considered to be the simplest "ketone" i.e. hydrocarbon containing a double-bonded oxygen to a carbon somewhere along the structure. This difference contributes to the polar dipole present within the molecule. When combined with the temporary London Dispersion Forces (LDFs) present within Acetone, we find that the structure has a relatively high melting point and boiling point of -95˚C and 56˚C, respectively. Therefore acetone is a liquid at Standard Temperature and Pressure. Although acetone is not regarded as a toxic molecule and no serious detrimental effects have been observed from exposure, it is nevertheless extremely flammable at temperatures where humans are handling it. However, most industrial acetone contains a small amount of water which prevents this kind of explosion from occurring. 

Acetone Ball and Stick Model
Acetone Ball and Stick Model. Created with MolView.
How is acetone utilized in the real world?

Since the compound is less polar than water, it serves as a solvent for many different intermediately polar molecules both in industrial and research capacities. For example, superglue is able to dissolve in acetone before hardening into its final form. Another example is acetylene (C2H2) which can dissolve in acetone and thereafter be safely transported. C2H2 cannot be safely pressurized in its pure form which is why acetone is required in this process. Furthermore, since acetone is a basic ketone it is utilized as an intermediate molecule in the formation of many more complex ketones and hydrocarbons. Acetone also finds extensive usage in the laboratory in order to clean glassware after complex chemistry experiments.

Is CH3F Polar or Nonpolar?

Answer: CH3F is a polar molecule due to the presence of a very electronegative fluorine (3.98) as one of the outer atoms which pulls electrons towards it inducing a partial negative charge. The other hydrogen's are therefore left with a partial positive charge. 

Due to this polar dipole CH3F has a far higher melting and boiling point (-138˚C and -78˚C, respectively) than methane. However since the fluorine is bonded to the carbon rather than to one of the hydrogen's the overall electronegativity difference is less and therefore these bonds are not as strong as H-F hydrogen bonds. Therefore fluoromethane (CH3F) is a gas at standard temperature and pressure. Although it has not been noted to be toxic to human health, the reactive nature of fluorine does make the structure flammable.

If you are interested in learning more about the related molecule CH4 (methane), feel free to check out this article on CH4's Lewis Dot Structure or CH4's polarity.

CH3F Ball and Stick Model
CH3F Ball and Stick Model. Created with MolView
How is CH3F utilized in the real world? 

Fluoromethane is utilized in processes involved with constructing semi-conductors. Another name for CH3F is Freon-41: "Freon" is a trademarked term by company that utilizes similar compounds in order to create refrigerants. Although CH3F does not have the same detrimental impact on the ozone layer that compounds combining chlorine, carbon and fluorine have, CH3F is a noted greenhouse gas that contributes significantly to global warming. Due to this reason, CH3F has been phased out from use in industrial applications. 

Is ClF3 Polar or Nonpolar?

Answer: ClF3 is a polar molecule due to the presence of two pairs of lone pair electrons. The resulting electron-electron repulsion causes a bent structure, leading to an unequal distribution of charge. This induces a permanent dipole. 

Due to the presence of extremely electronegative fluorines (3.98) the impact of the lone pairs of electrons is dented and therefore the dipole moment is weaker than in a comparable molecule such as ClH3. As a result ClF3 has a melting point of -76˚C and a boiling point of 12˚C. At Standard Temperature and Pressure (as defined by IUPAC - not the definition of the U.S. Imperial System) the molecule is a liquid. Due to the large number of fluorines the molecule is able to form a large amount of other compounds involving fluorine.

ClF3 Ball and Stick Model
ClF3 Ball and Stick Model. Created with MolView.
How is ClF3 utilized in the real world?

Due to large amount of halides within the molecule the substance is extremely poisonous, toxic, reactive and combustible. Since the bonds store a large amount of energy there is little input required to encourage these effects. As a result of handling concerns (since it can spontaneously burn living tissue) ClF3 has a few very specialized uses. It can be utilized in the semiconductor industry to clean chemical vapor deposition chambers since it can remove the metal from the machines without requiring the walls to be replaced. It was also explored for potential military applications and rocket fuel but manufacturing and usage difficulties prevented these from becoming a reality on a large scale.

Is CO Polar or Nonpolar?

Answer: CO is a polar molecule due to the large electronegativity difference between oxygen (3.44) and carbon (2.55) within the linear structure. Oxygen is left with a partial negative charge and carbon is left with a partial positive charge. 

Although the molecule is considered to be polar the necessary distribution of charge throughout the molecule does not match with the prediction. Since carbon is triple-bonded to oxygen, carbon requires a lone pair of electrons in order to complete its valence shell. When you therefore count the formal charges - carbon "possesses" five valence electrons and has a charge of -1. Conversely oxygen also "possesses" five valence electrons and has a charge of +1. This runs against the prediction made by electronegativity but this is a consequence of the necessary bonding structure. Therefore the polarity caused by electronegativity runs against distribution of charged electrons. As a result, the molecule shows a far weaker polar dipole. There are two consequences of this: 1.) carbon monoxide has a low melting and boiling point which are both near -200˚C and 2.) the structure is unstable and only lasts for short periods of time when it naturally appears in the atmosphere.

To learn more about the more stable yet related molecule Carbon Dioxide (CO2), feel free to check out the following articles regarding the polarity and the Lewis Dot Structure for CO2.

CO Ball and Stick Model
CO Ball and Stick Model. Created with Avogadro.
How is carbon monoxide (CO) utilized in the real world?

Although CO in quantities greater than 35 ppm is toxic since it disrupts normal hemoglobin function, carbon monoxide has been shown to play a role within the human body as a signaling molecule; for example, serving as a neurotransmitter or blood vessel relaxant. As a result of these properties, CO has been investigated in medical research studies as a possible anti-inflammatory agent. Carbon monoxide also finds use in chemical manufacturing and metallurgy (i.e. reducing metals from ores) due to its status as the simplest oxocarbon (i.e. the simplest combination of carbon and oxygen possible). 

Is Methanol Polar or Nonpolar?

Answer: Methanol is a polar molecule due to the presence of a hydroxide (-OH) group capable of hydrogen bonding due to the large electronegativity difference between oxygen (3.44) and hydrogen (2.20). This portion of the structure contains distinct partial negative charges (oxygen) and partial positive charges (hydrogen). 

Due to the presence of the hydroxide group and the minimal number of CH2/CH3 groups, this molecule qualifies as the simplest alcohol with the greatest polar dipole. This allows the molecule to be a liquid with a melting point of -98˚C and a relatively high boiling point of 65˚C. Methanol was originally extracted from wood which is why the substance is often known as wood alcohol. Today the structure is produced mainly as a combination between carbon monoxide (CO) and hydrogen (H2). Please note that methanol is toxic to humans and that even small doses can have devastating effects. The molecule acts on both the central nervous system and the mitochondria of cells, destroying both of these mechanisms and thereby inducing permanent blindness or death. This mostly commonly occurs due to the contamination of drinking alcohol with methanol. 

Methanol Ball and Stick Model
Methanol Ball and Stick Model. Created with MolView.
How is methanol utilized in the real world?

Since methanol is the simplest alcohol, it is often utilized as a precursor in the formation of other more complex molecules. This includes formaldehyde (CH2O), longer hydrocarbons and gasoline. In fact, fuel in the European Union may contain up to 3% methanol and engines theoretically could run on this substance in far larger concentrations. However, this runs into the practical problem that methanol is much more corrosive than other fuel types and therefore may decrease the life of the engine parts. Methanol as a polar solvent also has uses in wastewater treatment and sanitation efforts.

Is IF5 Polar or Nonpolar?

Answer: IF5 is a polar molecule due the presence of a lone pair of electrons which due to electron-electron repulsion results in a bent structure. This leads to an unequal distribution of charge within the molecule and therefore a permanent dipole. 

Although you may based on the large number of fluorines (the great electronegativity (3.98) pulls electrons/negative charge in its direction) assume that IF5 (iodine pentafluoride) has a relatively weak dipole moment, the other important consideration is the large number of electrons present within the molecule. This permits the molecule to create quite powerful temporary charges (also known as London Dispersion Forces) within the molecule in addition to the dipole moment. These two combined forces allow the molecule to be in a liquid state at Standard Temperature and Pressure (STP). The molecule has a melting point of 9.4˚C and a boiling point of 98˚C, making the intermolecular forces nearly as strong as those present in the much smaller H2O molecule.

IF5 Ball and Stick Model
IF5 Ball and Stick Model. Created with MolView.
How is IF5 utilized in the real world? 

Due to the large number of fluorine atoms present in the IF5 molecule it finds use in reactions that require the addition of fluorine halogens to some other molecule/compound. In addition to this usage IF5 is occasionally used as a special solvent for certain specialized applications.

Is NCl3 Polar or Nonpolar?

Answer: NCl3 is a polar molecule due the presence of a lone pair of electrons. This leads to electron-electron repulsion which results in a bent structure, thereby causing an unequal distribution of charge within the molecule and creating a permanent dipole.  

Since there are three quite electronegative chlorines (3.16) the impact of the lone-pair electron is less and therefore the dipole moment is weaker than a molecule such as ammonia (NH3). This is why NCl3 has a lower melting and boiling point (-40˚C and 71˚C, respectively) than ammonia. In fact, NCl3 can be combined with water to produce NH3 and hypochlorous acid.

To learn more about a similar molecule (ammonia), feel free to check out the following articles regarding the polarity and the Lewis Dot Structure for NH3.

NCl3 Ball and Stick Model
NCl3 Ball and Stick Model. Created with MolView.
Where is NCl3 found in the real world?

The molecule is most often formed as a byproduct from reactions involving ammonia-derivatives and chlorine. One of the most common places where NCl3 is formed is at swimming pools. The liquid formed is a "yellow" color and is responsible for the distinctive chlorine smell found at chlorinated swimming pools. The large number of halides makes the molecule unstable being sensitive to many different forms of energy input which typically lead to an explosion.

Is Oil Polar or Nonpolar?

Answer: Oil is typically nonpolar due to it containing many nonpolar covalent C-H (carbon-hydrogen) and C-C (carbon-carbon) bonds. These are often arranged in long chains which exhibit nonpolar characteristics. 

There are a great variety of different kinds of oils since it includes any nonpolar molecule that is a viscous liquid at Standard Temperature and Pressure (STP). Organic oils found in different biological organisms are typically called lipids. Mineral oils which form petrochemicals (i.e. the oil from the ground) are the second main type. Mineral oils actually result from the fossilized remains of organisms. Oil has been a staple of human life in different forms for many millennia.

To learn more about the polarity of a specific kind of oil named benzene (i.e. characterized by a carbon ring), please navigate to the following url:

Different Kinds of Oils
Different Kinds of Oils. Source
How is oil utilized in the real world?

Since oil encompasses a whole class of different molecules, there are a wide variety of uses including in cooking, cosmetics, energy and painting. The specific structures that are found in each of these applications vary depending on the specific purpose. Longer hydrocarbons typically store a large amount of energy which makes it either an optimal source of fats (typically unsaturated if still in liquid form) or energy for car fuel.

Is NOCl Polar or Nonpolar?

Answer: NOCl is a polar molecule due to the presence of a lone pair of electrons on the central nitrogen atom. The resulting electron-electron repulsion leads to a bent structure. Therefore, the structure has a permanent dipole due to the unequal distribution of charge. 

The impact of the lone-pairs in creating a region of negative charge on the nitrogen is dented by the opposing chlorine and oxygen atoms on the other side of the molecule. Due to the great electronegativity of these molecules -3.16 and 3.44, respectively- there is also a natural tendency for these atoms to pull electrons/negative charge towards themselves. This decreases the overall strength of the permanent dipole. Therefore the molecule is a gas at Standard Temperature and Pressure (STP) with a melting point of -59˚C and a boiling point of -5.5˚C. While is is higher than many nonpolar molecules, it is lower than molecules capable of hydrogen bonding such as water or ammonia.

NOCl Ball and Stick Model
NOCl Ball and Stick Model. Created with MolView.
How is NOCl utilized in the real world?

NOCl is often called Tilden's reagent. It can be utilized in a wide variety of organic chemistry reactions where it typically oxidizes some molecule. It is utilized in industrial processes to produce nylon-6 since the molecule can be broken up into its constituent Cl and NO parts with photon energy.

Is NH2 Polar or Nonpolar?

Answer: NH2 is a polar molecule due to the presence of lone pair electrons which result in a bent structure thereby causing an unequal distribution of charge within the molecule. This logic applies to either NH2+ or NH2- although the latter is more likely to occur.

Due to the necessity for nitrogen to either lose an electron (which is quite difficult due to nitrogen's high natural electronegativity of 3.04) or gain an electron (since three lone pair electrons cannot exist stably) this molecule is only found as an intermediate form in nature in certain reactions. The molecule is extremely unstable and typically lasts for less than one second.

To learn more about the intricately related molecule Ammonia (NH3), feel free to check out the following articles regarding the polarity and the Lewis Dot Structure for NH3.

NH2 Ball and Stick Diagram. Created with Avagadro.
How is NH2 utilized in the real world?

NH2- is typically one part of the alkali metal amides. NH2+ is typically the intermediate in a few specific kinds of organic chemistry reactions such as the Bamberger rearrangement and DNA-damaging processes. The most popular term to refer to NH2 functional groups is amine. Amine groups play an important role in the chain linking different amino acids together into their primary structure during translation of mRNA into protein.

Creating a Multiple-Choice Quiz Application in Scratch

Welcome back! In this tutorial we will learn how to create a multiple-choice application in Scratch. You may choose the theme/topic of your multiple choice quiz separate from the example contained here.

Objective: To learn how to utilize the list datatype to create a question/answer database through an indexing scheme. You will also try out the text2speech extension provided through Amazon's web servers.

Final Product (Example of U.S. Gov. Quiz):

Graphical Template: Link

*Please note that you will need to import the text2speech extension in the same way you imported the music (MIDI) and pen extension. If you need a reminder on how to do that please visit either of those two tutorials: MIDI & Pen.*



Sprite 4 Scripts


Sprite3 Scripts


AnswerThePublic Sprite


Sprite2 Scripts


Next Question Button Scripts


Audio Text2Speech Scratch Scripts


String Combiner Script


Question and Answer Database Creation

Please note that in order to add more questions you will need to duplicate the script (right click on the question "add" command and hit duplicate) in groups of five (i.e. you add another question and four answers to the chain). In my example I ended up with four-hundred add statements which is the equivalent of eighty questions!

Debugging: Check over the way you arrange you addition statements for the questions/answers. If these are in the wrong order then you won't be able to successfully index through the database!

Completed Example: Link (same as final product)

Creating a Millisecond Clock in Scratch

Welcome back! In this tutorial we will learn how to create an accurate millisecond clock (i.e. a clock that shows milliseconds). Although it will be difficult to follow the count with your eyes, you will begin to understand the difficulties associated with accurately keeping track of time during projects. Although many projects do not require a degree of accuracy to milliseconds, some animations may require this to function properly.

At the time this project was designed by @makethebrainhappy, this is the most accurate timer on the Scratch website.

Objective: To learn how to utilize the "timer" and other features related to time within the Scratch interface.

Final Product:

Please note that I overlayed the tab on the Scratch project to note how the Scratch "seconds" variable pulls from the actual time in seconds.   

Graphical Template: Link (for this tutorial you can put the scripts into the background - you can place any non-sprite related blocks in this workspace).


Millisecond Timer Script

How accurate is the millisecond timer really?

We can test out this theory by slowing down the video and seeing if the millisecond timer speed matches up with the change in seconds (i.e. 1000 milliseconds pass for each second).

Watch the video and see whether the millisecond timer works!

Completed Project: Link

Creating a Simple Gravity Script in Scratch

Welcome back! In this tutorial we will be creating an "egg bounce" to simulate a gravity script. We will be utilizing two broadcasting scripts to bounce up and down with the sprite. 

Objective: To learn about gravity physics scripts and broadcasting. This lesson also focuses on the "repeat until" block. 

Final Product: 

Graphic Template: (the "see inside" button will pull up the programming interface)

Physics: The physics in this lesson is based on the first two kinematic equations from the AP Physics 1 equation sheet. 

These two equations essentially relate position (where you are in space), velocity (how fast you are moving) and acceleration (how quickly you are speeding up). You can think about how this applies when are traveling in a car (position of the car, speed of the car and acceleration of the car). When you are for example traveling at a constant 55 mph down the highway, you are traveling at constant velocity and zero acceleration. When you are entering and exiting the highway you are either experience a considerable amount of acceleration or deceleration. 

Gravity on earth is roughly 9.8 m/s^2 towards earth (this is why an object like a ball thrown up in the air returns to earth). The numbers I used a roughly analogous to those on earth but they don't really have the same meaning in the context of the Scratch stage. Here the positive/distance is measured in x and y coordinates. As we go over in this lecture, the dimensions of the stage are -180 to 180 in the y-direction and -240 to 240 in the x-direction. This is context in which the sprites are traveling. I encourage you to change the different values and see how that impacts the "gravity script" of the sprite.


Bounce up/bounce down loop scripts.
Tips: Make sure that you are bouncing between the correct messages. Remember that you need to place to egg on the screen by clicking before it will bounce up and down. 

Completed Program: Link

Is C2H6 Polar or Nonpolar?

Answer: C2H6 (ethane) is a nonpolar molecule because it contains only nonpolar covalent bonds (C-H) bonds with both parts of the molecule cancelling out any small charge to ensure that there is no dipole moment. 

At standard temperature and pressure C2H6 is a gas due to its relatively low molecular mass for a hydrocarbon allowing for only weak London Dispersion Forces. Since it is a nonpolar molecule, few permanent dipole-dipole interactions can occur. This is unlike the unequal distribution of charge found in CH2F2 where some of the outer molecules were more electronegative. If some of the hydrogen molecules in this molecule were replaced with more electronegative elements that would open the possibility of polar interactions. 

If you are interested in more hydrocarbons, feel free to check out this article concerning the polarity of benzene

C2H6 Ball and Stick Model
C2H6 Ball and Stick Model. Created with MolView.
How is ethane utilized in the real world?

Oftentimes ethane (which is a saturated hydrocarbon because it only contains single bonds) is converted to ethene (an unsaturated hydrocarbon with a carbon double bond instead of a single bond). Ethene can then be utilized in a wide variety of reactions to create detergents, hasten fruit ripening or make plastic by polymerization. Ethane can itself also be utilized as a refrigerant. The molecule is oftentimes a by-product of petroleum production.