(25) What Are Periods & Groups In The Periodic Table? | Properties of Matter | Chemistry | FuseSchool

Periodic Table

A table that organizes elements based on recurring properties, arranged in periods and groups.

Period

Rows in the Periodic Table going from left to right, where elements share the same number of energy shells.

Group

Columns in the Periodic Table going from top to bottom, where elements have the same number of valence electrons.

Valence Electrons

Electrons in the outermost shell of an atom, available for reactions and bond formation.

Group 7

A group in the Periodic Table that includes Fluorine, Chlorine, Iodine, Bromine, and Astatine, all having 7 valence electrons.

Reactivity

The tendency of an element to engage in chemical reactions, influenced by the number of valence electrons.

Energy Shells

Layers of electrons surrounding the nucleus of an atom; each new period adds a new shell.

Chlorine

An element in Group 7, Period 3 with 3 energy levels and 7 valence electrons.

Hydrogen

The element in the first period of the Periodic Table, which has one energy shell.

Potassium

An element in the fourth period of the Periodic Table, which has four energy shells.