Question

An atom has an atomic number of 19 and mass number of 39 how many electrons and protons does it have? ​

Answer 1

19 protons, 20 neutrons and 18 electrons.

Step-by-step explanation:

The atomic number gives the number of protons 19

p = 19

The atomic mass is the sum of the protons and neutrons

p + n = 39 p = 19

put p into the equation and solve for n the neutrons.

19 + n = 39

Subtract 19 from both sides

19 − 19 + n = 39 − 19

n = 20

The number of electrons equals the number of protons in a neutral atom. The positive charge equals the negative charge. The negative charge is the number of electrons. This ion has a charge of +1. So solve for the negative charge.

− 19 + 1 = − 18

The negative charge is -18 so

e = 18