Nuclear & Particle Physics - Electron Configuration

The ground state electron configuration for phosphorus, which has 15 electrons, is 

A. 1s² 2s² 2p⁶ 3s¹ 3p⁴
B. 1s² 2s² 2p⁶ 3s² 3p³
C. 1s² 2s² 2p⁶ 3s² 3d³
D. 1s² 2s² 2p⁶ 3s¹ 3d⁴
E. 1s² 2s² 2p⁶ 3p²3d³

(GR0177 #17)

Solution:

Phosphorus (15 electrons):  1s² 2s² 2p⁶ 3s² 3p³

Answer: B



Note: 

Electron configuration

	l = 0	l = 1	l = 2	l = 3	# of electrons
n = 1	1s2				2
n = 2	2s2	2p6			8
n = 3	3s2	3p6	3d10		18
n = 4	4s2	4p6	4d10	4f14	32