Each of these elements has distinct chemical characteristics. Table 4a-1 lists some of the chemical characteristics for 48 common elements found in the Earth's continental crust . The smallest particle that exhibits the unique chemical characteristics of an element is known as an atom . Atoms are composed of yet smaller particles known as protons , neutrons , and electrons . A proton is a subatomic particle that has significant mass and contributes a single positive electrical charge to an atom.
Neutrons also have significant mass but no electrical charge.
Each electron also has a negative electrical charge. Protons and neutrons make up the nucleus of an atom. As a result, most of an atom's mass is concentrated in the nucleus. Because protons are positively charged the nucleus has a positive charge equal to the number of these subatomic particles. Electrons are found orbiting outside the nucleus at various distances based on their energy level.