What is an example of atom, element and compound and why?

An element is a substance that is made entirely of one type of atom. For example, the element sodium is made up of only sodium atoms. A compound is a substance that is made up of two or more different elements that are chemically joined, such as H2O,CO,NaCl .

Explanation:

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.