Ok this is mostly for chemistry, I suppose, but I said biology because that's my class. Just... some of biology requires knowledge of chemistry to fully understand it, I suppose. Anyway I have a test tomorrow and need to understand some things I'm having trouble with! Couldn't even study Japanese today.

Some of my current issues:

-How to understand bonding. I've got hydrogen bonding down, pretty simple. Ionic bonding should just be between a metal and non-metal, so if it's, say, sodium and phosphorus it should be ionic? But I don't understand covalent bonding (polar and non-polar). In understanding this, please do not use electronegativity, because she didn't talk about it. I need another way to figure them out!

-For a question it asks how to form water vapor. Not quite sure about this. It's probably easy, please don't call me stupid.

Might ask more, but please pray for me on this test tomorrow. D: Oh my...

For the majority of what you said, I have no idea. I remember doing things like that back in the day, but I've no clue.

Except...don't you just make water vapor by boiling it? Turning water into steam...that's "vapor" right?

I need the process. Like... having to do with the atoms. What happens to the bonds when it becomes steam, basically.

For covalent bonding isn't it just sharing electrons in the outer shell for a more stable configuration. If I recall correct, the electrons and nucleus, made of protons and neutrons, are attracted to one another.
As for polar and non-polar, that's more an issue with the angle of bonds I think.
Water as a liquid is H2O, water as a gas is H2O. Nothing should happen to the bonds. Its just adding energy I think.
I'm just recalling.

You are confusing intER molecular bonds and intRA molecular bonds (I think). IntER molecular bonds are broken when H20 becomes a vapor (ie. the hydrogen bonds, london forces, dipole dipole, ect break). The IntRA molecular bonds, the bonds from element to element, remain intact.

**In other words to form water vapor you break the molecule-molecule bonds/forces.** You do NOT need to break the element-element bonds.

If you are looking at a heating curve the flat part is where (latent) heat is being used to break those intER molecular forces.


....Geez, I sure hope I remembered all that correctly, its been a while

Okay so the hydrogen bonds breaking forms water vapor? Because that's sort of what I was thinking. It's still "water" but just in vapor form. Hope I understood you.

And yeah I sort of get the idea of atomic bonding, but it hasn't clicked for me. My teacher sucks, she didn't really explain it. I guess I'm at fault for not pursuing more information, but I've been working on studying for at least 6 hours today and with a friend in my class, so it's a bit disheartening that neither of us quite understand atomic bonding.

The kinetic energy of the water molecules becomes greater than the sticky hydrogen bonding forces that keep the liquid together.

For bonding.. that's a little more complex. Strange that you say you have hydrogen bonding down, as that's actually the most complex in terms of what is physically (chemically) happening.

Ionic bonding is when there are positive atoms/molecules and negative atoms/molecules mixed together, and the electric force pulls them all together into alternating ...+/-/+/-... crystal patterns. Therefore you need an atom/molecule that can form positive ions (typically metals), and an atom/molecule that can form negative ions (typically nonmetals). You can also get extremely complex ionic bonding structures with impurities or more than two elemental ions, but that's probably outside the realm of a biology class.

Covalent bonding is where two atomic nuclei share electrons, resulting in a single electronic structure. We call this a molecule. All molecules are covalently bonded structures. Covalent bonding typically occurs between nonmetals, although there are exceptions.

There is also metalic bonding which in a certain way is similar to covalent bonding (electrons are shared between the bonded atoms), but chemically quite different because the electrons are free to move around the molecule, at least at certain energy levels. (In actuality, covalent and metallic bonding are two extremes of a continuum, and the exceptions mentioned above are the borderline cases (like semiconductors) which are hard to classify.)

Here's a quick summary of what I can remember of covalent bonds:

All the elements on the right side (yeah I know terrible explanation but I forget what they are called - the typical ones like Carbon, Oxygen, nitrogen, etc) have rings of electrons.

The number they have on the table of elements is equal to their number of electrons.

The way the rings work is they get filled up gradually and when they fill then it goes to a new ring layer to fill up

so some of the elements are filled (the ones of the right most column, noble gasses) perfectly, but the ones that are not filled like oxygen, nitrogen, carbon, etc want to get full amounts of electons on the outermost ring

so they overlap their electrons with other unfilled elements, which causes a covalent bond

imagine this:

two oxygen atoms
one atom has 7 electrons on its outside ring, and it will be full when it has 8
the other atom has the same thing

the electrons more or less are placed around the atom like this:
. .
. .
O
. [ ]
. .

the [ ] shows where another electron should go and the O is the atom. the periods are electrons. As you can see there are 7 electrons around it with one gap.

The other oxygen comes in with that same thing, 3 pairs of eletrons and one unpaired.

basically the two 'unpaired ones' pair up by the two atoms coming very close to each other so they overlap

let me draw it for you
http://ploader.net/files/b039d55a6ab7ec3...5af2e3.png

haha

Lol thanks you guys. Also the picture really helped. I kept imagining the other electron as disappearing, so I suppose I forgot they're sharing it. How would you deal with multiples? One of the questions on the study guide says to figure out what bond N(2)O(4) is, the parenthesis being lower-case numbers. So 2 nitrogens and 4 oxygens. It has to be polar or non-polar, so in this situation what's the best way to examine it? I have to sleep soon, then I wake up and try to study in-between classes. Oh god, haha.

This is a little more complicated, haha

Basically you have to know more indepth knowledge of these atoms but

Nitrogen has 5 electrons on its outermost ring oxygen has 6 (my diagram up there wasn't exactly accurate lol)

the diffrence between 'nonpolar' and 'polar' basically is

if it's nonpolar, the electrons are shared evenly

aka: O = O
two oxygens pulling on the electorns evenly. Because oxygen has a table of elements number of 8, which means it has '8' pull (you said don't say electronegativity... lol!), so two '8' pulls cancels each other out

however when you have two different types, like N and O, the N has a lower number, and thus a weaker pull on those electrons (please someone correct me if I'm wrong)

so electrons will in fact, in the covalent bond, be closer to the oxygen, although they will still be sharing, the oxygen will pull on it more

so looking at N2O4, the most likely way those will be oriented is like this:
http://ploader.net/files/d7287a47642078b...8d9ecf.png

The explanation is that O has more pull on electrons than N because it has more protons (aka a higher atomic number so a higher number on the periodic table). since there are not only O's that are unbalancing things, but TWO Os on each side, electrons will be closer to the O's on each side

someone please check my work, chem isn't my strong subject

I'm surprised - this isn't really biology, it's really just chemistry

I'm thinking there must be some method she has taught or expects you to know to quickly do this because this is beyond the scope of a biology class unless you're taking an advanced level biology class in college which it doesn't seem like it

so check your notes or her lecture slides or something to see if she has any tips because, if she didn't even talk about electronegativity it is quit edifficult for you do determine the difference of a nonpolar and polar covalent bond just by looking at the chemical makeup of the molecule.

48/55 on my exam, just to let you know. I'll be bumping this next exam if you don't mind? ._.

Congrats on the score!

Maybe it doesn't matter now, but N2O4 would be a nonpolar molecule, if I remember correctly. zachandhobbes is right that the bonds are polar because the differing electronegativity of oxygen and nitrogen, but overall the molecule is symmetrical so the dipole moments of each will cancel each other out. That's probably what the question was asking for.