CHEMISTRY COMMUNITY

Siya Shah 1J

I think you should just for the sake of being well-versed and prepared for possible questions. I'm sure we should know the most basic ones as we are being tested on acids and bases as well as coordination compounds.

Siya Shah 1J

An amphiprotic substance is an amphoteric substance that transfers H+ ions.

Siya Shah 1J

Likely the two sig figs comes from the value of concentration 0.025 M.

Siya Shah 1J

The trend for ionic radius is the same for that of atomic radius, but the discrepancy is that when you go down a period towards nonmetals that form anions, the ionic radius jumps as anions are larger than cations, but then continues to follow the trend.

Siya Shah 1J

An amphiprotic species refers to the characteristic of being able to act as both an acid and a base. Amphoteric refers to the same thing, but an amphiprotic substance is an amphoteric substance that transfers H+ ions.

Siya Shah 1J

The correct answer on my test was 9 hydrogen bonds.

Siya Shah 1J

I believe H3O+ is just another way to represent H+ ions in water. I believe [H3O+] is equivalent to the [H+].

Siya Shah 1J

Victoria Otuya 4F wrote:Are sigma single bonds, and pi double bonds? I am confused on how to count those bonds?

A single bond is a sigma bond. A double bond has a sigma bond and a pi bond. A triple bond has a sigma bond and two pi bonds.

Siya Shah 1J

I think it would be best to just memorize whatever you can. I know someone who said cisplatin showed up on their final last year. Just memorize whatever you can just in case.

Siya Shah 1J

An anion is more stable when it has a higher electronegativity and thus attracts more electrons. This means an anion that is more polarizable is also more stable.

Siya Shah 1J

A substitution reaction is a reaction in which one functional group in a chemical compound is replaced by another functional group. This kind of reaction has great biological significance.

Siya Shah 1J

Not all bases have OH-. Ammonia, NH3 is a base, but is accepts an H+ therefore it is a base.

Siya Shah 1J

A ligand is a molecule, atoms or ion that is bound to a central atom.

Siya Shah 1J

You look at the Lewis structure and count the number of atoms and lone pairs bonded to the central atoms to determine hybrid orbitals.

Siya Shah 1J

It is the number of molecules, ions, or atoms bound to the central atom. The surrounding molecules, ions, or atoms are called ligands.

Siya Shah 1J

Can someone explain the exception for oxygen and nitrogen? It was on the midterm and I got it wrong. According to the trend, oxygen should have a higher ionization energy than nitrogen. However, nitrogen has its p-subshell half-filled and is relatively stable and low energy. Oxygen has one more ele...

Siya Shah 1J

You're definitely right; the lone pair should cause enough repulsion to distort the angles at least slightly in comparison to the bond angles of a trigonal bipyramidal molecule. I assume that's where the "approximately" 90º and 120º comes in?

Siya Shah 1J

The formula would be AX3 because there are three regions of electron density surrounding the central atom. They are all bonded pairs of electrons, so the formula would include X3. If any of the regions of electron density included lone pairs of electrons, you would have to use the E part of the form...

Siya Shah 1J

I believe if the molecule has four regions of electron density, then it cannot be trigonal planar. If it has four regions of electron density, three of which are bonded pairs, then the molecule would be called trigonal pyramidal.

Siya Shah 1J

Trigonal planar and trigonal pyramidal are not the same thing, even though each have three bonding pairs. Trigonal pyramidal has three bonding pairs and an additional lone pair, making a total of four regions of electron density. The lone pair causes repulsion, pushing the bonded pairs away from one...

Siya Shah 1J

Most common conversions are available on the equation and constants sheet and most likely there won't be any problems that require an arbitrary conversion not given on the sheet.

Siya Shah 1J

Polarizability is for atoms that tend to form anions and have larger electron clouds and it measures how much those electron clouds can be distorted. Polarizing power is for the cations that have the nuclear power to distort electron clouds of other atoms.

Siya Shah 1J

Larger molecules have more electron repulsion and larger electron clouds and are therefore more prone to distortion than smaller molecules.

Siya Shah 1J

Electrons can be distorted when there is a nearby atom that has a higher polarizing power that pulls on the electron cloud, introducing distortion.

Siya Shah 1J

Ionic bonds are stronger than covalent bonds because of the larger difference in electronegativity.

Siya Shah 1J

The central atom tends to be the least electronegative and the one with the most unpaired valence electrons.

Siya Shah 1J

Electronegativity is the measure of the attraction of electrons to a certain atom. Therefore, electronegativity influences both electron affinity, the energy released when an electron is added to an atom, and ionization energy, the energy requires to remove an electron.

Siya Shah 1J

Also, often you will be shifting around with the different types of bonds when drawing the various resonance structures for a compound. This usually entails removing double or triple bonds and turning them into single bonds and adding formal charges.

Siya Shah 1J

Longer bonds are weaker than shorter bonds and are therefore easier to break. Also, single bonds are longer than double bonds.

Siya Shah 1J

Yes, the most stable resonance structures or Lewis diagrams in general include as many formal charges of 0 as possible.

Siya Shah 1J

Micah3J wrote:What kind of questions might there be regarding the Aufbau Principle on a test?

The Aufbau Principle is mostly applied to writing out electron configurations for atoms of different elements.

Siya Shah 1J

Why is the second ionization energy of an element always higher?? Ionization energy is the energy required to remove an electron from an atoms. The second ionization energy is the energy required to remove an electron from a cation with a +1 charge. In this cation, there is already one more proton ...

Siya Shah 1J

I just want to clarify that we can still turn in quantum world hw questions as the 5 questions due in section? I have them done and don't want to find out later that I won't get credit. Homework can be any problem you want but it would be better if it is from the topic we're covering in class simul...

Siya Shah 1J

Resonance structures are essentially all the ways one molecule can be represented using a Lewis structure. The real molecule that exists is actually a blend of all the possible structures. I think most likely you would be required to always consider resonance and draw as many structures as you can.

Siya Shah 1J

If an atom, such as oxygen, forms a double bond and has two lone pairs of electrons, should I draw the dots for the lone pairs on diagonal sides of the O (on the other side of the double bond lines), rather than on the top and the bottom? Personally, I like placing the lone pairs on the top and bot...

Siya Shah 1J

The electrons cannot pair up first because they would repel one another, so the lowest energy scenario is if one electron fills up the orbitals first.

Siya Shah 1J

Also, this spin number is important to know because it determines whether or not an atom can generate a magnetic field.

Siya Shah 1J

The Principle Quantum Number (n) refers to the subshell. The orbital angular momentum quantum number l determines the shape of the orbital and the magnetic quantum number m(l) indicates how many orbitals there are in the subshell. Energy level is just a broader term for subshell.

Siya Shah 1J

Electron affinity is essentially the amount of energy released when an electron is added to a neutral atom in the gaseous state. Electron affinity increases as you go up the periodic table as well as when you go left to right on the periodic table. The added electrons become closer to the nucleus, c...

Siya Shah 1J

I believe what it is trying to say is that the strength of the nucleus pulling in the electrons is Z^2, which means that as the atomic number number increases, the nuclear charge Ze increases by the factor of Z^2.

Siya Shah 1J

De Broglie's equation concerns the variables of wavelength, velocity, and mass of an electron, as well as Planck's constant. The equation is used to describe the wave-like properties of elementary particles (including electrons), neutral atoms and molecules.

Siya Shah 1J

I think it is also important to mention that a lot of the equation we have discussed in this unit concern many of the same variables such as wavelength and frequency and you can use multiple equations or a combination of them to find the value you need.

Siya Shah 1J

Well, considering how far you've gotten, you know that NH3 is the limiting reactant for the reaction. So you would use the mole ratio between NH3 and NO multiply by the molar mass of NO to determine how many grams of NO are produced. You would do the same for H2O.

Siya Shah 1J

De Broglie's equation is used to describe the wave properties of matter, whereas Rydberg's equation is used to calculate the wavelength of a light emitted from an electron that moves between energy levels.

Siya Shah 1J

What is the relationship between amplitude and intensity of light? According to the same website as the comment above,"The intensity of a wave is proportional to the square of its amplitude." It's more of a physics concept so it's not likely that amplitude will be relevant to calculations...

Siya Shah 1J

I apologize for adding on to the initial question, but does anyone know if we will get points taken off of homework or exams if we do not put the state of matter next to the substances when writing a chemical equation? I don't know about points, although I expect in the future when we have to write...

Siya Shah 1J

He basically mentioned this just to demonstrate an example of why the actual, experimental yield of a certain reaction may be lower than the theoretical, calculated yield. It's not something we calculate, just a possible justification for the discrepancy between the actual and theoretical yield. If ...

Siya Shah 1J

No, as far as I know, the state of matter doesn't influence the balancing of chemical reactions; it's just more of an introduction to more complex chemistry concepts we're likely to learn soon.

Siya Shah 1J

Ok so this is how I'd approach it. I want to balance Fe first, so I add 2 in front of the product Fe to get Fe2O3 + CO >> 2Fe + CO2. Then, it seems like there are 4 O atoms on the reactants side and 2 on the products side, so it seems natural the 2 goes in front of the CO2. However, like you did, wh...

Siya Shah 1J

Do you think we will have to memorize the Avogadro's Number for test? I am wondering if I will be given the Avogadro's Number when I get the questions that ask for atoms' number. I don't know if we'll be given the number but honestly we use Avogadro's number often enough in calculations that it'll ...

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