The missing components in the table to the right are indicated with orange letters. Complete the
table by filling in the corresponding number(s) or
symbol(s) below.
A
B
1111
С
D
E
F
G

The Atomic Number (Z) indicates the number of protons in an atom of an element. If the atom is neutral then the number of protons will be equal to the number of electrons. So the atomic number can also indicate the number of electrons.

Mass Number (A) = Number of protons + Number of Neutrons

Atomic Number (Z) = Mass Number (A) - Number of Neutrons

Atomic number = number of protons = number of electrons  ⇒ neutral atoms

Atomic number - positive charge = number of electrons ⇒ cation

Atomic number + negative charge = number of electrons ⇒ anion

You can also see the periodic system

A. Indium (In)

B. proton = electron = 27

C. proton = electron = 73

D. proton = electron = 49

E=F. atomic mass - neutron = 137 - 81 = 56

G. atomic mass-proton = 115- 49 = 66

H. 181-73 = 108