Atomic Symbol

An Atom Identity Card

An atomic symbol is a compact way to write the identity of an atom. Like a student card that carries a name and an ID number, an atomic symbol carries the element symbol, atomic number, and mass number.

The Atomic Structure and Symbolism section from OpenStax explains that the atomic number is the number of protons, while the mass number is the number of protons plus neutrons. The section can be opened through OpenStax's Atomic Structure and Symbolism.

The notation commonly used in basic chemistry is:

{}^{A}_{Z}\mathrm{X}

Atomic Structure

Atomic Symbol

An Atom Identity Card

An atomic symbol is a compact way to write the identity of an atom. Like a student card that carries a name and an ID number, an atomic symbol carries the element symbol, atomic number, and mass number.

The Atomic Structure and Symbolism section from OpenStax explains that the atomic number is the number of protons, while the mass number is the number of protons plus neutrons. The section can be opened through OpenStax's Atomic Structure and Symbolism.

The notation commonly used in basic chemistry is:

{}^{A}_{Z}\mathrm{X}

What you read	Common form	Meaning
Mass number	A whole number, such as $12$ in ${}^{12}_{6}\mathrm{C}$	The number of protons plus neutrons in one specific atom.
Relative atomic mass	Often decimal, such as about $12.01$ for carbon	The average mass of isotopes in a natural sample.

Writing	How to read it
$\mathrm{C}$	Carbon
$\mathrm{Cl}$	Chlorine
$\mathrm{Co}$	Cobalt
$\mathrm{CO}$	Not one element, but the formula for carbon monoxide

Atomic Symbol

An Atom Identity Card

Atomic Symbol

An Atom Identity Card

Read the Numbers by Position

Three Core Counts

Carbon Example

Do Not Confuse It with Average Atomic Mass

Element Symbols Need Exact Capitalization