CHEM 232 Chapter Notes - Chapter 1: Isotopes Of Hydrogen, Dmitri Mendeleev, Semimetal
Document Summary
An element is a substance that contains only one type of atom. There are 91 elements that occur naturally, a total of 114 that have been given official names, and three more that have been produced but not named. This gives a total element count of 117. Trace elements are elements that the body needs small quantities of if it is to function properly. Oxygen, carbon, hydrogen, and nitrogen make up most of the mass of a human body, but many more elements play critical roles in the body"s chemistry. All atoms of a particular element have the same number of protons in their nucleus. The number of protons that an atom has in its nucleus is known as the atomic number. The total number of protons and neutrons in the nucleus of an atom is called the mass number. To specify the number of protons and neutrons in the nucleus of a particular atom, atomic notation is commonly used.
