ATOMS, ELEMENTS AND COMPOUNDS Atoms, elements and compounds are all matter. An atom is the smallest particle in ordinary matter that forms a chemical element. Atoms are extremely small. Every solid, liquid, gas or plasma is made up of atoms. - An element is a substance that cannot be broken down into simpler substances by chemical means. Elements are made up of atoms . What Elements Are Found in the Human Body? There are 92 elements that occur naturally on Earth. For living things, only 11 of these elements are found in larger than trace quantities (0.01% are less). The Top Four Elements Found in the Human Body Of the elements found in the human body, four of them make up the largest percentage of our body weight (96.2%). The four elements are oxygen, hydrogen, carbon, nitrogen. Why Oxygen? (O) Our cells combine oxygen with nitrogen and hydrogen to produce various proteins that build new cells. When oxygen is combined with carbon and hydrogen , you get carbohydrates tha