miércoles

Monday October 26th 2009

Today we talked about ionic bonds, but class started with a review of what makes up an atom. Which is the proton (positive), electron (negative), and neutron (neutral). Then he went on to tell us that each atom has the same number of neutrons, protons, and electrons, but that the mass is different; For this one is in a way the sum of the neutrons and protons (it is also the electrons but they barely make a difference so it is not very noticeable). Then we got to the actual subject IONIC BONDS.
To know what that is we need to understand what
ions are: The elements that have charges, there are two types: Cations (positive) and Anions (negative).
Now to get there we need to discuss metals and nonmetals.
"
Atoms of metals tend to lose their electron valances leaving a complete octect in the next energy level."
Which basically tells you that metals tend to give up electrons.
Example: Na (z=11) configuration= 1s
22s22p63s1which means it has 1 valance electron, and in order to be like a noble gas it has to lose one electron by doing this the atom goes from neutral to positive because now it has more protons than electrons. So it becomes a cation of sodium, because when they become cations they don't change the name.
-When you look at the periodic table: the number in the top right corner with the negative and positive charge tells you how many electrons ot gives or takes away and whether it becomes a positive or negative charge.
You can also look at he columns (1a, 2a, 3a, etc.) to know how many it loses.

Once an atom becomes a cation or anion it becomes different than the original even if it's a small different it can cause a lot of changes.


"
Atoms of nonmetals tend to gain electrons or to share electrons with another nonmetal to achive an octet."
(most not all)

example:Cl (z=17) configuration= 1s22s22p63s23p5so it needs one more electron to become a noble gas, and by gaining an electron it emds up having more electrons than protonsand is negative instead of neutral. There are some that become pseudo noble gas because they're not exactly a noble gas but they are stable.
When an atom becomes an anion you change the name by replacing the last syllable with -ide.
ex: Chlorine -> Chloride.

Now the best way to know if it loses or gains electrons is by looking at it's valance number:
if it's 1-3 it loses
if it's 5-7 it gains
if it's 4 then it's a metalloid and it can do either, lose or gain.

If you've paid attention you've realized that despite me saying we were going to talk about ionic bonds I have yet to say anything about them, that's because you need to know evrything I've just said before you understand what's next.
Ionic Bond is held together by electrostatic forces.
Metal cation + Nonmetal anion = Neutral compound
(+) (-)
(±)

Ex:
Na (+1) + Cl (-1) = NaCl

(P.S. Cations always go first it would never be written ClNa)

That was the whole class, and there was no homework.
Victoria Bracamontes

lunes

Friday, october 16th, 2009

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Erin Alice Gil

miércoles

Monday, October 5th, 2009



Today we saw a new theme: the periodic table.

First the teacher shows us a little bit of the past:

· 1860, only 60 elements were known.

· They knew only the basic stuff.

· Jöns Jakob Berzelius- made the 2 letter system for elements.

· Johann Döbereiner- was the 1st to “organize” the periodic table by the Law of Triads (groups of 3 elements because of their property.)

· John Newlands- use the Law of Octaves (groups of 8 elements), and he relate it with music scales.

· Mendeleev- He was the real 1st one who made a periodic table with 12 columns and 8 rows, also we left blank spaces – he predicts the properties of the missing elements. He was considered “Chemist of predictions.”

· Henry Moseley- he organized it by atomic numbers.

As well, teacher Ariel explained us the 2 letter system for elements, that is to use the first letter of the name in English; but also why some elements are not in that system, and that’s because some elements were first written in Latin and they kept that name like gold (Au) means Aurum in Latin, and after that, he gave us a list of the 5 elements in Latin:

*Aurum (Au) = Gold

*Kabium (K) = Potassium

*Natium (Na) = Sodium

*Ferrum (Fe) = Iron

*Argentums (Ag) = Silver

· Of all the elements, 83 elements are stable in nature, while 24 are not from earth.

Now, the periodical table is conformed of rows (horizontal) and columns (Vertical):

The horizontal are the Periods-the mass and size are similar in each period.

The vertical are the Groups, and in these one are different classification:

1) Alkali Metal

2) Alkali earth metal

11) Coinage Metal- soft metals (gold, silver and copper)

17) Halogens- they separate vey easy.

18) Zero, Noble gases, Inert gases- the ones that are stable.

· Periodical table also use the electronic configuration helping you find a element more quick; the periods will be used as the biggest number of the list, example: if you got as the biggest one 3p4, then the period will be #3; and the groups are represented in these way:


Andrea Favela

lunes

Fridat, october 2nd, 2009

Today at the beginning Mr. Ariel said that he wasn't going to ask who found the homework hard, because apparently most of us had sent him e-mails asking for help, and he wet on to explain how it should've been done. When he drew it, one of the students realized that he had forgotten to tell us something when it comes to drawing the electrons in their shell. We thought that we were just adding the next drawing of the levels when really we were supposed to have 2 "s" levels and then the first "p" leve, when most of us thought that we only draw the s level once and then the p and so on, so he made it clcear that we're suppossed to draw the "s" level once again as we get to a new level. Also he gave us a hand out that tells us the order of the electron configuration and said that that would help us understand how to place the electrons. It looked something like this, with arrows telling you to go diagonally down from right to left:
1s
2s 2p
3s 3p
4s 4p 4d
5s 5p 5d
6s 6p 6d 6f
7s 7p 7d 7f

Also it had a picture of Bohr's model of the atom and it had how many electrons could fit in each of the levels and the order of them. And he explained it as if it was a concert stadium with all the seats beong the same price. First you fill the front row tickest which aare 1s and 2s then you move on to the ones that get farther and farther away. We did a buch of execercises with them and the first 5 to finish one of them would get an extra point in the test. One of the questions was the electron configuration of Gold (79) which was:

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d9

And he left Platinum's electron configuration for homework.


Victoria Bracamontes