# If an element has atomic number 9 and atomic mass 19, how many neutrons will it have?

##### 2 Answers

May 3, 2017

#### Answer:

TEN neutrons.........

#### Explanation:

To an excellent approximation, atomic mass is equivalent to nuclear mass; i.e. the combined mass of neutrons and protons. Can you tell us the identity of the nuclide? You have all the info necessary to do so.

May 11, 2017

#### Answer:

10 neutrons.

#### Explanation:

We know that Mass number

Mass Number = Number of Protons + Number of Neutrons;

And Atomic Number = Number of Protons.

So Number of Neutrons = Atomic Mass - Atomic Number = 19 - 9 = 10

This explains the answer.