To figure out how many neutrons are in an atom, you need to know two important numbers: the atomic number and the mass number. Let’s break these down.

1. Atomic Number (Z):

   • This is the number of protons in the center of an atom.
   • It tells you what the element is.
   • For example, carbon has an atomic number of 6.

2. Mass Number (A):

   • This is the total number of protons and neutrons in the center of the atom.
   • For the most common type of carbon, called carbon-12, the mass number is 12.

To find out how many neutrons (N) are in an atom, you can use this simple formula:

$$N = A - Z$$

Example Calculation:

• For carbon:
  • The atomic number (Z) is 6.
  • The mass number (A) is 12.
  • So, you do the math:
  $$N = 12 - 6 = 6$$

This means that carbon has 6 neutrons.

Summary

• Atomic Number (Z): This is the number of protons in the atom.
• Mass Number (A): This is the number of protons plus the number of neutrons.
• How to Calculate Neutrons: Use the formula $N = A - Z$.

Understanding the number of neutrons is important for learning about isotopes. Isotopes are different versions of the same element, but they have different mass numbers because they have a different number of neutrons.

For example, carbon-12 and carbon-14 are two isotopes of carbon.