Periodic table

Definition

The periodic table organizes all known chemical elements in a tabular format based on their atomic number, electron configuration, and recurring chemical properties. Elements are arranged in rows called periods and columns called groups or families.

5 Must Know Facts For Your Next Test

1. The periodic table was first created by Dmitri Mendeleev in 1869.
2. Elements are listed in order of increasing atomic number, which is the number of protons in an atom's nucleus.
3. Rows (periods) indicate the number of electron shells an element's atoms possess.
4. Columns (groups) contain elements with similar chemical behaviors due to having the same number of valence electrons.
5. The periodic table helps predict elemental interactions and bonding patterns essential for understanding molecules and compounds.

Review Questions

• What determines the order of elements on the periodic table?
• Why do elements in the same column have similar chemical properties?
• How does the periodic table help predict the behavior of elements during chemical reactions?

Related terms

Atom: The smallest unit of matter that retains the identity of a chemical element.

Isotope: Variants of a particular chemical element that differ in neutron number but have the same proton number.

Ion: An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.