Some substances, like particles of this iron, contain only one kind of atom. Iron is an element. It is made of only one type of atom: iron atoms. Sulfur is another element. It contains only sulfur ...

It is the number of protons, otherwise known as the atomic number, that determines which element any given atom represents. If an atom has 2 protons, that’s an atom of the element helium.

Electronegativity, an essential characteristic of all elements in the periodic table, measures an atom's ability to attract electrons towards itself within a chemical bond. This vital theoretical ...