Question

In isotope sodium-25, what are the atomic number, number of protons, electrons, and neutrons?

Answer 1

Remember, the atomic number of an atom is always its proton number.

For this problem, sodium is atomic number 11. This means it has 11 protons. Since the mass of the isotope is 25 amu, that means the neutron number needs to be 11 + n = 25. Solve for this and you get 14 neutrons. Since the isotope is neutral charge, its electrons equals its protons. Therefore the electron number is also 11.

Answers:

Atomic number: 11

Protons: 11

Electrons: 11

Neutrons: 14

Answer 2

11 protons, 11 electrons, 14 neutrons

Step-by-step explanation:

Na has atomic number Z = 11, so it has 11 protons (p).

In a neutral atom, the number of protons equals the number of electrons, so there are 11 electrons.

The mass number A =the number of protons plus neutrons = p + n

So, to get the number of neutrons, you take

A – Z = (p + n) – p = n

In words, number of protons = mass number – atomic number

Number = 25 – 11 = 14 .