# of protons # of neutrons
# of electrons
Atomic Number
Mass Number
18
17
35
17
37
6
8
6
6
15

17 protons, 18 neutrons, 18 electrons

This is a chloride ion. According to the periodic table, there are 17 protons because the element is chlorine. There are 18 electrons due to the negative charge: 17-(-1) = 18. There are 18 neutrons because 35-17=18.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8