Describing the Periodic Table It arranges all the known elements in an organized chart. Elements are arranged left to right and top to bottom in order of increasing atomic number and (usually) atomic mass
Types of Elements 3 main types of elements –Metals –Metalloids –Nonmetals
Rows - elements of each row have the same number of energy levels (shells). Columns - elements have the same number of electrons in the outermost energy level or shell (one to eight).
Periods The different rows of elements are called periods. –The period number of an element shows the highest energy level that has at least one electron.
Family The different columns of elements are called groups or families –Elements in the same family have similar properties