Science 8: The Periodic Table – Periods and Groups

Vocabulary flashcards covering the organization of the periodic table, including periods, groups, atomic numbers, valence electrons, electron shells, and chemical reactivity.

Periods

The horizontal rows on the periodic table that run from left to right, totaling 7 periods in total.

Groups

The vertical columns on the periodic table that run from top to bottom, totaling 18 groups in total.

Atomic Number

The identifying value that increases by one from left to right across each period and determines the position of each element in the periodic table.

Period Number

A number that indicates the total number of electron shells an element has; each new period down the periodic table adds one additional electron shell around the nucleus.

Valence Electrons

Electrons situated in the outermost electron shell of an atom that determine chemical bonding, reactivity, and the group to which an element belongs.

Representative Elements

Elements categorized in Groups 1, 2, and 13–18 whose group number directly corresponds to their valence electron count.

Valence Electron Rule for Groups 13–18

The method of subtracting 10 from the group number to determine the number of valence electrons for representative elements (e.g., Group 17 has 7 valence electrons).

Reactivity

The ease with which an element undergoes chemical reactions by gaining, losing, or sharing electrons.

Metals (Periodic Table)

Elements located on the left side of the periodic table that possess fewer valence electrons and tend to lose them to form positive ions.

Nonmetals (Periodic Table)

Elements located on the right side of the periodic table that possess more valence electrons and tend to gain electrons to form stable negative ions.

Group 1 Elements

Highly reactive metals containing exactly 1 electron in their outermost shell, which they easily donate during chemical reactions.

Group 18 Noble Gases

Elements characterized by full valence electron shells (e.g., neon with 8 valence electrons), rendering them extremely stable and chemically unreactive.