Answers to periodic table worksheet

9- To figure out valence electrons in 3, you have to do electron configuration. Al is element #13. This means you list the shells, then the electrons in the shells, until you add up to 13. 1s = shell, # after = # electrons in that shell. There are 4 types of shells. S takes 2 electrons, P takes 6, D takes 10 and F takes 14. Here's the order for the energy shells. http://www.mwt.net/~bionorse/electron%20…
E. Config = 1s2 2s2 2p6 3s2 3p1, because 2+2+6+2+1 = 13. Therefore, you have a total of 3 electrons in the 3rd energy level, because 2 are in 3s and 1 is in 3p. Easy!
10- name = Aluminum
11- symbol = Al
12- atomic # = see top left of the box
13- mass = see bottom of the box
14- # neutrons = Mass Number (rounded to next whole #) = (Number of Protons) + (Number of Neutrons). 27 = 13 + x... solve for x, you have # neutrons for aluminum.

3) A halogen again, huh? Should be simple.
15- what group did we look in last time?
16- # valence electrons = all halogens have a -1 charge, thus they have 7 electrons in their valence shell. This is something you memorize by group #. Trick question.
17- element = Chlorine
18- symbol = Cl
19- # protons = # protons and # electrons is EQUAL, since one is pos and one is neg. But you know what the atomic # is, the # protons -- what's the atomic #? (Hint, they tell you here # electrons is 17... so what is # protons?)
20- # neutrons is? You just did this. 35=17+x

4) element is the largest of period three. Remember your periodic trends? Here's a reminder.
http://www.meta-synthesis.com/webbook/24…
Here's how you figure out periods: http://en.wikipedia.org/wiki/Period_(per…
Basically, a period includes all the elements in that energy level (you need to do the electronic configuration). Since we know from trends also that groups 1-2=S, groups 3-8=P, the transition metals are D, and the actinides for the most part are F, this helps in configuring elements.
Elements get bigger the further down the table you go. Hence:
21- element = Argon
22- symbol = Ar
23- atomic # = 18
24- family = This is another name for GROUP. Which vertical column is this element in? Just look at the table. Hint - it's the only group with all 8 of their electrons, completely nonreactive elements. They have a special name.

5)Element with 56 protons
25- atomic # - What did we say # protons is for each element?
26- mass - Look at the bottom of the box.
27- valence electrons - What group is it in? That will automatically give you valence electrons.
28- group - Where is it on the table?
29- element - Find Element 56... which one is it?
30- symbol - Starts with a B....

Good luck, hope this helps and that you learned something useful! :)