The atomic mass of the atom is composed of the mass of protons + electrons neutrons + electrons protons + neutrons just neutrons

Answer : The atomic mass of the atom is composed of the mass of protons + neutrons.

Explanation :

Atomic number : It is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Atomic mass : It is defined as the sum of number of protons and number of neutrons.

Atomic mass = Number of protons  + Number of neutrons

For example : The sodium (Na) elements has atomic number 11. That means, the number of electrons and number of protons is equal to 11. The number of neutrons are 12. So, the atomic mass will be:

Atomic mass of Na = Number of protons  + Number of neutrons

Atomic mass of Na = 11 + 12 = 23

Hence, the atomic mass of the atom is composed of the mass of protons + neutrons.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.