Question

Consider the two electron arrangements for neutral atoms A and B. What is the difference between atom A and atom B?

A - 1s22s22p63s1

B - 1s22s22p65s1

Atom B has lost some inner electrons.
The outer electron of atom B has moved to a lower energy state.
The outer electron of atom B has moved to a higher energy state.

Answer 1

The normal pattern of filling of electron shells is from lowest energy to the highest and it goes 1s, then when there are two electrons in this level then 2 can go in 2s, then there's room for 6 in 2p shells. 3s is normally filled, followed by 3p - you can see this in the shape of the columns in the periodic table. The next after 3p is 4s so if electrons are ina higher level they must have a higher energy state.