atoms that are now stable because they have gained or lost valence electrons resulting a positively or negatively charged atom

a type of chemical bond formed between ions with opposite charges (+ and -) therefore, it is

mostly elements from the left side of the periodic table combining with those from the right side

+ -

always the same elements in the same proportion ex- NaCl (1:1) CaCl2 (1:2)

Al2O3 (2:3)

atoms gain or lose valence electrons in order to have a full valence shell (2 or 8) ex) Na has one valence electron,

therefore it would lose it and be +1 charged (this is referred to as its ionic charge)

ex) O has six valence electrons, therefore it would gain two and be -2 charged

+ +- -

e-

Na gives Cl one electron and now both atoms are stable

it is easier to just draw Lewis-dot structures to show valence electrons instead of the drawing the whole atom

An oxidation number indicates the charge on the atom (or ion) when electrons are lost, gained, or shared in chemical bonds

the oxidation numbers for all the atoms in a compound must add up to zero

  ...etc.

As it turns out, atoms bond together for a very simple reason: atoms like to have full valence shells (2 or 8).

1+ 2+ 3-3+ 4+/- 2- 1- 0

sometimes it takes more than one of each atom to make the compound “work”

Mg and Cl?

it takes two chlorines to combine with one magnesium MgCl2 → magnesium chloride

Mg and N? it takes two

nitrogens to combine with three magnesiums Mg3N2

magnesium nitride

Easiest way is to switch the charge numbers and write them as subscripts on the formula.

Be +2 and N 3-

Be3 N2

beryllium nitride

there is only one way ions can combine, therefore there is only one name for each compound formed

keep the first element’s name the same change the second element ending to

ide sodium and chlorine (NaCl) becomes…

sodium chloride

magnesium and fluorine (MgF2)…. magnesium fluoride

K and P (K3P) potassium phosphide