Why do different elements have different charges?

[Fifty]

Since I was first introduced to chemistry, it's been because "it has two more than eight, and it wants eight to be "happy" so it loses two electrons and gains a positive two charge."

It's good enough for me to write on tests, but 'happy' isn't exactly a scientifically accurate term.
And why can similar elements have different charges? For example, why can oxygen be 2 and 1, but phosphorus (same group) can be +/- 3, 5 and -2?

 

[Borek]

Short answer: the answer lies in limits quantum chemistry puts on electron configurations.

 

[DrDu]

Since when are oxygen and phosphorus in the same group?

 

[tiny-tim]

Hi Fifty!

… 'happy' isn't exactly a scientifically accurate term.

'happy' means 'with lower energy' …

any system naturally prefers the configuration with the lowest energy

if chlorine can grab an electron from sodium, then the chlorine-sodium pair has lower energy, and is 'happier'

 

[Fifty]

Since when are oxygen and phosphorus in the same group?

Sorry, for some inexplicable reason I always get Sulphur and Phosphorus confused.

 

[Fifty]

Hi Fifty!


'happy' means 'with lower energy' …

any system naturally prefers the configuration with the lowest energy

if chlorine can grab an electron from sodium, then the chlorine-sodium pair has lower energy, and is 'happier'

How, exactly does this work? There is still the same amount of particles (and matter) so why should the Sodium Chloride particle have less energy than one Sodium atom and one Chlorine atom?