Understanding atoms is simpler when we look at two important ideas: atomic number and mass number.

Atomic Number:

The atomic number is the number of protons inside the nucleus of an atom.

We use the letter ( Z ) to represent this number.

This number is special because it tells us what kind of element we're dealing with.

For example, hydrogen has an atomic number of 1, and carbon has an atomic number of 6.

The atomic number also helps us find the element's spot on the periodic table.

Mass Number:

The mass number, which we write as ( A ), counts both protons and neutrons in an atom's nucleus.

To find it, we can use this simple formula:

[ A = Z + N ]

Here, ( N ) is the number of neutrons.

Let’s look at carbon again to see this in action:

The most common version of carbon, called carbon-12, has 6 protons and 6 neutrons.

So, its mass number is 12.

But there's another version called carbon-14, which has 6 protons and 8 neutrons.

This means its mass number is 14.

By understanding atomic number and mass number, we get a clearer picture of atomic structure!