CHEMISTRY COMMUNITY

Natalie Nartz 4F

When in contact with water, strong acids and bases are able to fully dissociate due to their high Ka and Kb values. However weak acids and weak bases have lower Ka and Kb values so they are not able to completely ionize in water.

Natalie Nartz 4F

You know an acid is polyprotic when the acid can donate more than one proton to the solution. Examples would include H2S, H2CO3, H2SO4, etc

Natalie Nartz 4F

Examples of basic items would be bleach, baking soda, soapy water, and ammonia solution. Examples of acidic items would be lemon juices, gastric acid, and black coffee. Pure, distilled water is neutral

Natalie Nartz 4F

A lower pKa indicates a stronger acid. A low pKa means the Ka value is higher, meaning the acid dissociates faster, therefore making it stronger

Natalie Nartz 4F

To calculate pOH you could take the -log[OH-] or you could subtract the pH from 14. ( 14 = pH + pOH ) Either way the calculation of pOH is nothing to worry about :)

Natalie Nartz 4F

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

Natalie Nartz 4F

HCl is a stronger acid than HF. Since the fluorine atom is more electronegative the attraction between H and F will be greater than H and Cl, meaning that HCl will dissociate more likely than HF, making it a stronger acid

Natalie Nartz 4F

We don't actually have to calculate bond length quantitatively. Just remember single bonds are longer than double and triple bonds

Natalie Nartz 4F

The main distinction is that the cis- isomer is polar and the trans- is nonpolar

Natalie Nartz 4F

According to the Bronsted-Lowry defintion, acids are proton donors and bases are proton acceptors

Natalie Nartz 4F

Make sure that your formal charges equal the charge of the molecule, however they should still be minimized. Electrons should be counted before drawing the molecule to help determine how many bonds/lone pairs you will have

Natalie Nartz 4F

The VSEPR helps you qualitatively estimate bond angles based on the properties of the molecule, however it can not quantitatively give the exact bond angles

Natalie Nartz 4F

Lone pairs are more repulsive because they are less stable, bonding pairs are more stable because they are distributed between two atoms and therefore have a lower repulsion than lone pair.

Natalie Nartz 4F

Yes, the partial charges created by the dipoles makes the molecule polar

Natalie Nartz 4F

It would be beneficial to know: ion-dipole, h-bond, dipole-dipole, ion-induced dipole, dipole-induced dipole, and dispersion

Natalie Nartz 4F

London dispersion forces are temporary attractive forces the results when two electrons in two adjacent atoms occupy positions that create temporary dipoles. This why london dispersion forces can also be called induced dipole-induced dipole attraction.

Natalie Nartz 4F

An ion-dipole force occurs between an ion and a dipole. When a polar molecule and an ion come together, the cation will be attracted to the partially negative end of the polar molecule, and the anion will be attracted to the partially positive end. For example an ion dipole force can be generated be...

Natalie Nartz 4F

A covalent bond would be classified as a intramolecular force as it occurs within a molecule. Covalent bonds are intramolecular because they hold atoms together in molecules and polyatomic ions.

Natalie Nartz 4F

This is true, as molecules increase in size, their boiling point increases. This is because large molecules have more electrons and nuclei which creates stronger intramolecular forces like van der waals which then increases the boiling point.

Natalie Nartz 4F

A chemical bond is an attractive force between two atoms, sharing or exchange of electrons. Intermolecular forces are forces that occur between two or more molecules, and are much weaker than bonds.

Natalie Nartz 4F

Depends on the situation, just pay attention to the number of electrons and the octet rule

Natalie Nartz 4F

If magnitude is greater, the bond is harder to break, because it has the most potential energy stored in its bonds.

Natalie Nartz 4F

I don't believe we'll need to memorize this for the exam. I think Lavelle even mentioned an alternative equation to use instead.

Natalie Nartz 4F

I am not 100% sure, but I believe it is referring to the probability function that corresponds to every electron. The function tells us the probability of finding an electron within that orbital. I hope this helps!

Natalie Nartz 4F

I it couldn't hurt to memorize common polyatomic ions like ammonium and carbonate, etc, but I wouldn't stress about it.

Natalie Nartz 4F

I am not sure if we will be covering bond angles in class, but if we don't I think you're fine as long as correctly distribute the electrons.

Natalie Nartz 4F

Homework problems from the textbook are due in during your discussion time. Posts on chemistry community are due 11:59 pm Sunday night.

Natalie Nartz 4F

The periodic trends show that ionization energy increases when moving left to right. This is because when moving left to right across a period, atomic radius decreases, so electrons are more attracted to the nucleus. With this in mind, since Na is further left, it will have a lower ionization energy...

Natalie Nartz 4F

Resonance is way of describing bonding certain molecules in a combination of different ways. The chemical connectivity is the same however, the distribution of electrons varies in each structure. And it is the average of these structures, that we get the true structure of the molecule.

Natalie Nartz 4F

How many questions will the midterm be? What type? (multiple choice/open ended)

Natalie Nartz 4F

When removing an electron in the first ionization you ultimately make the atom more positive, which makes it harder for the second removal of an electron since now there is a stronger positive charge pulling on the electron.

Natalie Nartz 4F

Yes atomic, ionic, and covalent radii all share the same trend. Radius decreases across a period, and increases down a group

Natalie Nartz 4F

For part A, n= 2 and l=1 which makes it 2p, the p-subshell has three orbitals: 2px, 2py, 2pz. For part B n=4 l=2 and ml= -2 which represents only one orbital

I hope this help

Natalie Nartz 4F

I believe we are still on the quantum world unit, so I would just do problems from this section.

Natalie Nartz 4F

l is the angular momentum quantum number. Each value of l corresponds to a specific subshell and shape. Ex: l=0 would be the s subshell which has a spherical shape

I hope this helped

Natalie Nartz 4F

I don't think we'll have to memorize the specific values. But I think memorizing the order of the types of radiation in terms of wavelength would be beneficial. I think it would also be good to memorize the range of visible light which is around 400-700nm

Natalie Nartz 4F

Frequency measures the number of wave cycles in one second. Amplitude on the other hand, is the measured distance between the crest and the midline of a wave. They are independent.

Natalie Nartz 4F

h symbolizes planck's constant. It is used in this sense to relate energy in one quantum or photon of electromagnetic radiation to its corresponding frequency.

Natalie Nartz 4F

I don't think we'll have to memorize them. But, the masses of each are as follows

electron: 9.11*10^-31 kg
proton: 1.675*10^-27 kg
neutron: 1.673*10^-27 kg

Natalie Nartz 4F

I am not sure where your error is. For my mass I got .146 kg and my velocity was 41.126ms-1 , and I got 1.11*10^-34 as my final answer

Natalie Nartz 4F

I am not sure you need to know the structure of the polyatomic ions, but I believe it would be beneficial to memorize common polyatomic ions nitrate, nitrate, sulfate, phophate, etc.

Natalie Nartz 4F

The net ionic equation would look like this:

Cu+2 + 2OH- = Cu(OH)2

I hope this helps

Natalie Nartz 4F

First, you need the molar mass of Sr(NO2)2 which is 179.631 g/mol. Then calculate the mass of each element in the molecule, (Sr 87.62g, N 2(14.01g), O 4(16g)) Finally, take each of the element's masses and divide by the molar mass of strontium nitrate, then multiply by 100 to get the mass percent. S...

Natalie Nartz 4F

When writing or balancing equations for tests will we be required to include the state of each element? Ex: solid, liquid, gas, aqueous

Natalie Nartz 4F

I am not sure how to determine the energy needed to remove one electron from a sodium atom.
The given information is as follows:
- velocity of the ejected electron is 6.61 x 105 m.s-1
- work function for sodium is 150.6 kJ.mol-1
What equation would be best in this situation?

Natalie Nartz 4F

Why is the equation En= -(hR)/(n^2) negative? Does this deal with certain properties of the atom and/or electron?

Natalie Nartz 4F

Does absorption of a photon always lead to a later emission of a photon? If so, does this emitted photon have the same energy as the photon that was first absorbed?

Natalie Nartz 4F

When frequencies of light don’t match the energy differences of an atom, what happens to the light? Does this light simply pass through?

Natalie Nartz 4F

Refrain from rounding values within the problem it self when you are doing calculations. From my understanding, it is only appropriate to round to the correct number of significant figures when you have reached your final answer.

Natalie Nartz 4F

0.0850 would have 3 sig figs, as the two zeros before the 8 are not significant. However the trailing zero following the 5 would be significant

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