Hi! Can somebody please help me with a coupla questions? Thanks loads!!!

Describe physical and chemical properties of isotopes of the same element.

Given the electron configuration of an element, how can you tell whether it represents the element in its ground or excited state?

The density would be different, but all other things I can think of would be the same.

If at ground state, the configuration is the lowest possible.

What do you mean by its the lowest possible?

For example, look at K.
19K is 1s2 2s2 2p6 3s2 3p6 4s1 represents the lowest energy state for K.
Anything other than this; i.e.,
1s2 2s2 2p6 3s2 3p6 5s1 would not be its ground state.

OR 1s1 2s2 2p6 3s2 3p6 4s1 5s1 would not be its ground state.

So basically, if the configuration isn't as it is supposed to be, then it isn't at ground state?