key term - Groups

Definition

Groups are vertical columns in the periodic table, also known as families. Elements within a group share similar chemical properties due to having the same number of valence electrons.

5 Must Know Facts For Your Next Test

1. There are 18 groups in the modern periodic table.
2. Elements in the same group have similar chemical reactivity.
3. Group 1 elements are known as alkali metals and are highly reactive.
4. Group 17 elements are called halogens and are also very reactive, especially with alkali metals.
5. Group 18 contains noble gases, which are inert due to their full valence electron shells.

Review Questions

Related terms

Period: Horizontal rows on the periodic table where elements have the same number of electron shells.

Valence Electrons:

Electrons found in the outermost shell of an atom that determine its chemical behavior.

Periodic Law: The principle stating that elements arranged by increasing atomic number show a periodic pattern in their properties.