Element

Definition

An element is a pure substance consisting of only one type of atom, characterized by its unique number of protons in the atomic nucleus. Elements cannot be broken down into simpler substances by chemical means.

5 Must Know Facts For Your Next Test

1. Each element is defined by its atomic number, which is the number of protons in its nucleus.
2. Elements are represented by unique chemical symbols, such as H for hydrogen and O for oxygen.
3. The periodic table arranges elements based on their atomic number and properties.
4. Isotopes are variations of an element with different numbers of neutrons but the same number of protons.
5. Elements combine to form compounds through chemical reactions involving bonds between atoms.

Review Questions

• What defines an element's identity?
• How are elements arranged in the periodic table?
• What distinguishes isotopes of the same element from each other?

Related terms

Atom:

The smallest unit of an element that retains its chemical properties, consisting of a nucleus surrounded by electrons.

Compound:

A substance formed when two or more elements chemically bond together in fixed proportions.

Isotope:

Atoms of the same element that have different numbers of neutrons but the same number of protons.