Question

A particular atom of an element has a mass number of 15. There are 10 electrons in the -3 ion of the atom. Identify the element, using the correct element symbol, the number of protons and number of neutrons in this atom.

Answer 1

N

7 protons

8 neutrons

Step-by-step explanation:

The -3 ion of the atom principal means that the atom has received 3 extra electrons to become electrically charged negatively. Hence, before it has received 3 electrons. We need to know that the original number of electrons is 7.

For an electrically neutral atom, the number of protons is equal the number of electrons. This means that the number of protons is 7

An element could be identified by using the number of protons which is the atomic number. This means that the atomic number of the element is 7 and consequently the element in question is nitrogen N.

Now, we can obtain the number of neutrons since we now know the number of protons and the mass number. The number of neutrons is thus the mass number minus the atomic number or number of protons. This is this 15 -7 = 8

The number of neutrons is thus 8