CHEMISTRY COMMUNITY

Cynthia Gong 1L

Usually you would use the periodic table for this. Metals form basic oxides while nonmetals form acidic oxides. metalloids tend to form amphoteric oxides

Cynthia Gong 1L

In a basic solution water will form OH- while in an acidic solution water accepts an H+ and forms a hydronium ion H3O+

Cynthia Gong 1L

Decrease energy consumption, use renewable sources, burn clean coal

Cynthia Gong 1L

This is because oxygen is more electronegative and less likely to share its electrons with a proton

Cynthia Gong 1L

the strength of an acid can be ranked by the extent to which they ionize in an aqueous solution. Strong acids completely ionize, while weak acids only partially ionize

Cynthia Gong 1L

They are also strong because they completely dissociate in water

Cynthia Gong 1L

For complete ionic equations, write the balanced equation but with all strong electrolytes written as dissociated ions.

Cynthia Gong 1L

Acids are all aqueous because they must be able to dissociate in water. You are correct that when water is added, both products are aqueous as well.

Cynthia Gong 1L

I believe there was a chart Dr. Lavelle had sent out

Cynthia Gong 1L

I believe the II refers to the +2 charge of the nickel in the compound.

Cynthia Gong 1L

There is no specific interaction that would guarantee liquid state at room temperature, but a general guideline would be that gases have the weakest intermolecular interactions at room temperature (London Dispersion), liquids have interactions with strengths somewhere in between, and solids have the...

Cynthia Gong 1L

I think that's because the textbook used the resonance structure where there is one single-bonded O and one double-bonded O, and so as a result there is only one pi bond.

Cynthia Gong 1L

I'm interested in joining this group too! Where do you guys meet?

Cynthia Gong 1L

ionic bonds are stronger because the molecules will form a tightly knit crystal lattice structure that is extremely strong.

Cynthia Gong 1L

The intramolecular bond between HO would be stronger than the intramolecular bond between HS because of the stronger effective nuclear charge present in the nucleus of O. As a result, HO is more tightly bound.

Cynthia Gong 1L

On the other hand, intramolecular forces such as covalent bonding occur between the individual atoms in a molecule.

Cynthia Gong 1L

van der waals and london forces are terms that are typically used interchangeably.

Cynthia Gong 1L

An overall molecule has a dipole if there is a great difference in electronegativity between the individual atoms that compose that molecule.

Cynthia Gong 1L

To determine the type of intermolecular force present, you look at the the difference in electronegativity between the atoms in a molecule. If the there is a great difference in electronegativity, a dipole-dipole interaction will occur with other polarized molecules or a dipole-induced dipole intera...

Cynthia Gong 1L

Single, double ,and triple bonds are all considered one region of electron density in the VSEPR model. So regardless of resonance structures, the shape of the VSEPR model won't be affected.

Cynthia Gong 1L

^^ Building upon what they said, dipole moments occur because electrons are pulled towards the more electronegative side of the bond, so one side becomes more negatively charged while the other side becomes more positively charged

Cynthia Gong 1L

^^ Yep, he said he would try his best to get it done in a week.

Cynthia Gong 1L

Cation radii follows the normal atomic radii trend. It increases across a period and decreases down a group. This is because moving across, the number of protons increases, thus increasing effective nuclear charge and decreases the size. If we have 3 cations that are isoelectronic, for instance: Na+...

Cynthia Gong 1L

The most stable and ideal resonance structure would have a formal charge of 0 on each individual atom. However, that may not happen if the molecule is charged. If we have something such as SO4(2-), then the individual formal charges on each individual atom should add up to a total of -2. If a resona...

Cynthia Gong 1L

The least electronegative atom goes in the center since it is less likely to interact with the electrons in surrounding molecules. The more electronegative atoms typically go on the outside. It is ideal if all the formal charges are 0, but if that is not possible then negative formal charges should ...

Cynthia Gong 1L

Yep! It's going to be covered in the next unit and will be included in the final, but will not be part of our midterm.

Cynthia Gong 1L

The locations should be reposted again by the next class session, if not he will most likely email them to us.

Cynthia Gong 1L

I don't believe locations for the midterm have been released yet.

Cynthia Gong 1L

Double and Triple bonds have more electrons, so they exert a stronger attractive force on the nuclei of the other atom, thus pulling the two atoms close together and reducing the bond length.

Cynthia Gong 1L

Polarity definitely affects the bond strength. When you are talking about intermolecular bonds, polar bonds will always be stronger than non-polar bonds because polar bonds have dipole-dipole attraction, which are much stronger than the London Dispersion Forces that are only present in non-polar bon...

Cynthia Gong 1L

Another exception is electron affinity for noble gases. Electron affinity increases across a period until you get to a noble gas, because when an electron is added to the full shell of a noble gas, the stability of the atom becomes destroyed.

Cynthia Gong 1L

This is also because anions have more electrons, so there is more electron-electron repulsion present that causes the radius to be bigger.

Cynthia Gong 1L

You can go into the SAC's test bank and see if they have Lavelle's old midterm

Cynthia Gong 1L

For tests I believe everything will be in SI units. If not, we will get the conversion factors

Cynthia Gong 1L

Conceptually, the 2nd ionization energy is higher than the first because there is less electron-electron repulsion present in the atom, which results in the remaining electrons being "held" onto tighter. Similarly, the 3rd ionization energy will always be higher than the 2nd, and so on.

Cynthia Gong 1L

I believe there are color-coded periodic tables available that tell you what each type of element is:
ex. https://www.chemicalsafetyfacts.org/wp- ... d-650w.jpg

Cynthia Gong 1L

The 4d orbital does have a higher energy level than the 5s orbital. Higher principal quantum numbers aren't necessarily always associated with higher energy levels, such as this case of 4d vs. 5s.

Cynthia Gong 1L

The atomic radius is half the distance between the nuclei of two identical atoms bonded together. For the purpose of this class I don't think we would be calculating the exact value of the radius.

Cynthia Gong 1L

I believe +1/2 and -1/2 are the only possible spin states

Cynthia Gong 1L

Can someone summarize how to tell whether an atom is in the ground state or excited state?

Cynthia Gong 1L

The question will most likely ask you to calculate the uncertainty of momentum or the uncertainty in position

Cynthia Gong 1L

a) you know that the molar mass of water is ~18g, and that one mole of water contains 6.022 x 10^23 water molecules. To find the mass per molecule, simply divide the total molar mass by the number of water molecules b) molar mass of water is 18g, to find number of moles in 1kg divide 1kg (1000g) by ...

Cynthia Gong 1L

Can someone pls explain why n=1 is the ultraviolet region, but when an electron drops down from a higher level, it loses energy? I was under the assumption that waves in the ultraviolet region have higher energy.

Cynthia Gong 1L

^^ The technique above is what I was taught -- basically think of all of the decimals as fractions where you have to get rid of the denominator

Cynthia Gong 1L

@ ATingin_3I the t would stand for ton, and 1 ton equates to 1000kg

Cynthia Gong 1L

I think it will be sufficient if you do all the recommended problems since that gives you a good overview of all the different types of problem situations.

Cynthia Gong 1L

The limiting reactant should be the one that produces the fewest number of moles of product. That can be figured out by comparing mole ratios between that reactant and the product.

Cynthia Gong 1L

For all combustion problems, you would use molar ratios to solve for the empirical formula. For instance, in this problem you are given that there is 0.682 g of CO2 produced. The molecular weight of CO2 is around 44g, so you divide 0.682/44 to calculate the number of moles of CO2 that is produced in...

Cynthia Gong 1L

^^ That is correct! We can use water as an example. For instance, water is made of hydrogen and oxygen. Hydrogen has a molar mass of 1.0079g while oxygen has a molar mass of 15.999. The values of molar mass are found from the periodic table. Meanwhile, water is a molecule made up of oxygen and hydro...

Cynthia Gong 1L

I'm also interested! Hopefully we can get a few more people

Cynthia Gong 1L

Typically your answer would contain the least amount of sig figs that is present in the question. Since in the example the number 2.1 has the least amount of sig figs of 2, your solution would contain 2 sig figs. As a result I believe your decimal answer would be rounded to 5.0. Hopefully someone el...

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