Elements

Definition

Elements are pure substances consisting of only one type of atom. They cannot be broken down into simpler substances by chemical means.

5 Must Know Facts For Your Next Test

1. Each element has a unique number of protons in its nucleus, known as the atomic number.
2. Elements are organized in the periodic table according to their atomic numbers and properties.
3. There are currently 118 recognized elements, with some occurring naturally and others being synthesized in laboratories.
4. The chemical properties of an element are determined primarily by its electron configuration.
5. Isotopes are variants of elements that have the same number of protons but different numbers of neutrons.

Review Questions

• What defines the atomic number of an element?
• How are elements arranged in the periodic table?
• What is an isotope?

Related terms

Compound:

A substance formed when two or more different elements combine chemically in fixed proportions.

Molecule:

A group of atoms bonded together representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.

Atom:

The basic unit of a chemical element, consisting of a nucleus surrounded by electrons.