Gold

Gold (Au) is a transition metal with atomic number 79 and an atomic mass of 196.97. Its electron configuration is [Xe] 4f14 5d10 6s1.

Gold key data

Symbol	Au
Atomic number	79
Atomic mass (standard atomic weight)	196.97
Molar mass	196.97 g/mol
Protons	79
Neutrons (most abundant isotope, gold-197)	118
Electrons (neutral atom)	79
Category	Transition metal
Period	6
Group	11
Block	d-block
Noble gas notation	[Xe] 4f14 5d10 6s1
Full electron configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s1
Electrons per shell	2, 8, 18, 32, 18, 1

Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.

Measured properties of gold

From PubChem, the US National Institutes of Health. Public domain.

Melting point	1337.3 K (1064.2 °C), 44th of 103 by melting point
Boiling point	3129 K (2855.9 °C), 39th of 93 by boiling point
Density	19.28 g/cm³, 8th of 96 by density
State at room temperature	Solid
Electronegativity	2.54 (Pauling), 12th of 95 by electronegativity
Van der Waals radius	166 pm, 88th of 99 by atomic radius
First ionisation energy	9.226 eV (890.2 kJ/mol), 23rd of 102 by first ionisation energy
Electron affinity	2.309 eV (222.8 kJ/mol), 6th of 57 by electron affinity
Common oxidation states	+3, +1
Discovered	Ancient

Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.

Gold electron configuration

The full electron configuration of gold is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s1. With the noble-gas core collapsed it is [Xe] 4f14 5d10 6s1, and the outermost subshell is 6s1.

Gold does not follow the simple filling order. Its measured configuration differs from the one the aufbau rule predicts, because a filled d subshell sits lower in energy than the arrangement the rule would give. This is a measured fact about the atom rather than an exception to be derived.

Bohr model of gold (Au): a nucleus and six shells holding 2, 8, 18, 32, 18 and 1 electrons from the inside out. — Bohr model of gold (Au). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Orbital box diagram of gold (Au), [Xe] 4f14 5d10 6s1, with the xenon core drawn as one bar: one box per orbital, filled by Hund’s rule, showing one unpaired electron, in 6s. — Orbital diagram of gold (Au). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one gold atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

one atom = 196.97 / (6.02214076 × 10²³)
= 3.2708 × 10⁻²² g

Atoms in one gram

atoms per gram = 6.02214076 × 10²³ / 196.97
= 3.0574 × 10²¹ atoms

Gold on the periodic table

Gold is in period 6, group 11, in the d-block.

The other elements of group 11 are copper, silver and roentgenium.