Things To Know:

Periodic table

The periodic table is a chart that shows the chemical elements and their relationship to each other. The periodic table is a graphic way of representing the periodic law.

Words to Know

Atomic number: The number of protons in the nucleus of an atom; the number that appears over the element symbol in the periodic table.

Atomic weight: The average weight of all isotopes of a given element, expressed in units known as atomic mass units (amu).

Element: A pure substance that cannot be changed chemically into a simpler substance.

Family: A group of elements in the same column of the periodic table or in closely related columns of the table. (See Group.)

Group: A vertical column of the periodic table that contains elements possessing similar chemical characteristics. (See Family.)

Isotopes: Two or more forms of the same element with the same number of protons but different numbers of neutrons in the atomic nucleus.

Nucleus: The small core at the center of an atom that contains protons and (usually) neutrons.

Period: A horizontal row of elements in the periodic table. (See Row.)

Row: A horizontal set of elements in the periodic table. (See Period.)