What does the atomic number tell you

Explanation:

The atomic number tells you how many protons are in an element. Each element has a different number of protons, so a specific number of protons will also help you easily identify that particular element. For example, if you are given that an element has an atomic number of 1, you would know the element is hydrogen because other elements have different amounts of protons and thus different atomic numbers.

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).