CHEMISTRY COMMUNITY

Nancy Hu - 4E

Is it possible to ever have a negative oxidation number? If so how would that be reflected in the name because there is no +/- sign in the brackets Yes it is possible to have a negative oxidation number. To show that it is an anion, you would add -ate at the end of the central atom's name, and its ...

Nancy Hu - 4E

It is possible when there is a strong acid with a molar concentration greater than 1 mol/L.

Nancy Hu - 4E

Tetrahedral uses the notation AX4 while square planar is AX4E2. This means that tetrahedral has 4 bonds to the center atom. Square planar has 4 bonds and 2 lone pair on the center atom.

Nancy Hu - 4E

If the structure is asymmetrical, the dipole moments won't cancel out and so the molecule would be polar.

Nancy Hu - 4E

Pi bonds by themselves are actually weaker than sigma bonds because there is less area of overlap between p orbitals than s orbitals. Single bonds are weaker than double bonds because single bonds has only a sigma bond while double bonds have a sigma and pi bond.

Nancy Hu - 4E

Yes, pi bonds only form when unhybridized p orbitals overlap.

Nancy Hu - 4E

Single, double, and triple bonds are one area of bonding, so they all count as one region of electron density.

Nancy Hu - 4E

So is any element in the first 3 groups without a d-orbital in its shell unable to fulfill the octet rule? Under my current understanding, I believe any element in the first three groups don't have to meet the octet rule of maximum 8 electrons, it can exceed the octet rule since it has access to th...

Nancy Hu - 4E

Delta bonds are formed when 4 lobes of a d orbital overlaps with 4 lobes of another d orbital.

Nancy Hu - 4E

The final review sessions aren't posted on the website yet, but I would assume that they start soon. They'll probably start after Thanksgiving break.

Nancy Hu - 4E

Lone pairs would push the other bonding pairs further away, so the bond angles are usually less than the bond angles for the original shape.

Nancy Hu - 4E

It would be easier to memorize them. You can also figure out the shapes by knowing how many areas of electron density there are and the lone pairs with the notation.

Nancy Hu - 4E

Make sure that the formal charges are closest to zero. A way that makes it easier for me is to keep the valence electrons for each element in mind when drawing the lewis structure so that I don't have to guess and check the formal charges for the best structure.

Nancy Hu - 4E

There is also pentagonal bipyramidal.

Nancy Hu - 4E

The oxygen in H2O is electronegative and can form intermolecular hydrogen bonds. On the other hand, H2S has Van Der Waals force between the molecules instead of hydrogen bonds. The h-bonds between the hydrogen and oxygen of water molecules are stronger than the Van Der Walls force so the melting poi...

Nancy Hu - 4E

The order of increasing ionic radius is Cl^1-,S^2-,P^3- because even though they have the same electron configuration, the smaller ions are the ones with the larger atomic number because they have the most positive charge in the nucleus because of the number of protons and so they have the largest p...

Nancy Hu - 4E

Atomic radius and ionic radius are both the measure of the center of the nucleus and the outermost shell. In a neutral atom, both the atomic and ionic radius would be the same. The ionic radius is bigger in a anion and smaller in a cation compared to their parent atom.

Nancy Hu - 4E

A TA told me that they will give the compounds but we should still know the basic ones like NaOH.

Nancy Hu - 4E

Trends and electron configuration are related in that you can see the reasoning behind the trends when writing out the electron configurations of elements. For example, a full valence shell is the most stable electron configuration.

Nancy Hu - 4E

Our TA's might go over what is on the midterm during discussions. It also might be helpful to look at the practice problems that review session have.

Nancy Hu - 4E

Can someone help explain why H, He, Li, and Be are exceptions to the octet rule?

Nancy Hu - 4E

So the 4th quantum number describes the spin of an electron. If the electron is spinning up, it has a value of +1/2. If the electron is spinning down, it has a value of -1/2. It is just used to describe the orientation of an electron in an orbital.

Nancy Hu - 4E

During discussion, my TA said that we don't need to know how to do calculations using the Schrodinger equation for the test. We just need to know the concepts behind the equation.

Nancy Hu - 4E

Electron configuration plays a part in quantum numbers so it would probably be better to know the electron configurations for the test. Even if it isn't on the test, it wouldn't hurt to look over it a little.

Nancy Hu - 4E

The excess energy is used to eject electrons so it is converted into kinetic energy. Kinetic energy can be solved by using the formula 1/2mv^2.

Nancy Hu - 4E

When the photon is greater than or equal to the threshold energy, electrons can be ejected.

Nancy Hu - 4E

I don't know when the grades for the discussion or homework will be posted, but my TA passed back the homework assignment from week one in my discussion this week.

Nancy Hu - 4E

It's really just personal preference. If you find it a lot easier to write out numbers especially long ones in scientific notation, you can. It's also a lot easier to use scientific notaion when you want to keep numbers at a certain sig fig.

Nancy Hu - 4E

It is just a lot easier to do calculations if you change the percentage based on 100g. You don't have to do any complicated calculations.

Nancy Hu - 4E

Hi! So you count zeros when there's a decimal point after for example in 280. there are 3 sig figs. If you have a number like 0.0005 where the zeros are after the decimal point you only have one sig fig. if you have a number with zeros in the middle you would count them for example 34.008 that is 5 ...

CHEMISTRY COMMUNITY

Search found 30 matches

Re: Roman Numeral

Re: Negative pH?

Re: Tetrahedral vs. square-planar

Re: Polarity of Asymmetrical Molecules

Re: sigma and pi bonds

Re: Non hybrid orbitals and pi bonds

Re: VSEPR RULE 3

Re: Octet Expansion and d-Orbitals

Re: Delta Bonds

Re: Review for Final

Re: Bond Angles

Re: Test 3

Re: Lewis Structure

Re: Naming the shape

Re: Melting points

Re: Ionic Radius

Re: Difference between Atomic Radius and Ionic Radius

Re: Midterm Chemical Formula Names

Re: Trends in the periodic table & electron configuration

Re: Midterm

Exceptions to octet rule

Re: 4th quantum number question [ENDORSED]

Re: Test 2 and Shrodinger Equation

Re: Next week's quiz

Re: Photoelectric Effect

Re: Photon energy

Re: Homework and discussion grading?

Re: Scientific Notation

Re: Empirical formula set up

Re: Zeros in sig figs