Life on the Edge

Valence and Core Electrons

Electron Shells - levels around nucleus where electrons can be found Atomic # - number of electrons

Period # - number of shells ex: period 1 has one shell, period two has to shells, etc...

Group # - number of valence electrons; this gives element in the same group some similarities

Valence Shell - outermost shell of atom

Valence electrons - electrons in the valence shell

Core electrons - all electrons not in valence shell

Noble Gas Envy

Ions

Ion - atom or group of atoms with a positive or negative charge because it lost or gained electrons

Metal atoms transfer electrons to nonmetal atoms when they form compounds.

When the metal and nonmetal atoms combine they want to fill their valence shells to become like noble gases that have 8 in their valence shells
They need to be balanced when they combine. This means that the total number of valence electrons of the two elements need to be a multiple of eight.

Ideally you want compound like elements from group 2 that have 2 valence electrons combining with an element from group 6 which have 6 valence electrons so their total valence electron count is 8. Or from group 1 combining with group 7. These all make it easier.

A lot of the time though The combinations can be with group 1 and group 6 which together only equal 7. However, if you add one more of the same element from group 1 that gives you 1 valence electron from each equalling 2 to add with the group 6 element, giving you 8 total.

For example: say you want to find the chemical equation for combining sodium, Na and oxygen, O. Sodium is in group 1 with one valence electron and oxygen is in group 6 with 6 valence electrons. By adding one more sodium atom it gives you 2 electrons to give to the oxygen atom to fill its she'll, giving you Na2O.

Cation - positive charge (metal)

Anion - negative charge (nonmetal)