# What is the isotope symbol for an atom that contain 2 protons and 1 neutron?

Aug 5, 2018

 ""_2^3He

#### Explanation:

The subscript of 2 represents the two protons the superscript of 3 represents the total mass of 3 2 protons + 1 neutron = 3 amu mass.

Aug 5, 2018

The isotope symbol for helium-3 is $\text{_2^3"He}$.

#### Explanation:

Helium-3 contains 2 protons and 1 neutron.
Here's the general formula to write isotope symbols

$\text{_B^A"C}$

A Represents the mass number

B represents the atomic number

C Represents the element symbol