Consider these elements: p, ca, si, s, ga.

a. write the electron configuration for each element

Method:

1) Find the atomic number in a periodic table: the number of electrons equal the atomic number

2) Use Aufbau rule

Element atomic number electron configuration

P 15 1s2 2s2 2p6 3s2 3p3

Ca 20 1s2 2s2 2p6 3s2 3p6 4s2

Si 14 1s2 2s2 2p6 3s2 3p2

S 16 1s2 2s2 2p6 3s2 3p4

Ga 31. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p