Question

Consider the two electron arrangements for neutral atoms A and B. Which atom is more stable?

A - 1s2, 2s2, 2p6, 3s1
B - 1s2, 2s2, 2p6, 5s1


A
B
indeterminate

Answer 1

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Answer 2

As the atoms are neutral, the number of electrons will equal the number of protons which will be the atomic number. So A has 2 electrons in the first orbital, 2 in the second, 6 in the third and 1 in the 4. So the total, the atomic number is 11. Doing the same for B and you also get 11. So they have the same element...

What has happened is that the electron in 3s1 of A has been promoted (absorbed energy) to 5s1. So the outer electron of B has been promoted to a higher energy state. As atoms like to be in the ground state, where the electrons are in the lowest possible orbital, A is the most stable.

Answer 3

ok thank u.....