Question

HELP ASAP

A neutral atom of phosphorus was found to have an atomic number of 15 and a mass
number of 31. What is the total number of electrons in this atom?
a.8
b.15
c.31
d.16

Answer 1

B. 15

Step-by-step explanation:

The atomic number of an element is the number of protons found in the nucleus of an atom of that element. This means that every phosphorus atom has 15 protons.

The mass number of an element is the total number of protons and neutrons found in the nucleus of an atom of that element. This means that, in total, every phosphorus atom has 31 protons and neutrons (15 protons and 16 neutrons).

So that an atom is neutral, it needs to have the same number of protons and electrons. This means that the number of electrons will be the same as the atomic number. The phosphorus atom has 15 electrons.

This is why the correct option is option B.