How many protons, electrons, and neutrons are there in the following atoms and ions?

19 protons, 20 neutrons and 18 electrons.

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

no

sodium is solid at rt