Question

Using the periodic table, determine the ion charges of the following elements if valence electrons were removed or added to reach the octet.

barium =

iodine =

potassium =

aluminum =

Answer 1

Well for every proton you have an electron. When an atoms protons equal its number of electrons then you have a neutral atom (no charge).

When you add an electron the charge decreases by -1
When you remove an electron the charge increases by +1

Answer 2

Also, you might want to know when to add or remove electrons, it depends on the electronegative of the element. Electronegativity being its affinity for electrons (how hard it holds onto its electrons).

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTW2WHPA63nt9Qy4CqS_Y6TSU1KKqg6PKmLSJAo1Jp_2KaxQLdlAg

Answer 3

Oops http://0.tqn.com/d/chemistry/1/0/w/v/PeriodicTableElectronegativity.jpg

Answer 4

Also note that as you go down the table the non valence electrons shield the nucleus more and more making the ability making the hold on the valence electrons weaker and weaker. So size of the atom also plays a role on electronegativity.

Essentially Groups 1, 2 and 3 lose electrons and Groups 5, 6 and 7 gain electrons, Group 4 can go either way and that is why it is one of the most interesting groups :)