Gold (Au)
Gold is element 79, a transition metal in group 11, period 6. A neutral atom has 79 protons, 118 neutrons and 79 electrons, 1 of them valence electrons.
Transition metal- Atomic number
- 79
- Atomic mass
- 196.97 u
- Valence electrons
- 1*
- Protons · neutrons
- 79 · 118
- Electrons per shell
- 2, 8, 18, 32, 18, 1
- At room temperature
- solid
Bohr model of gold
The Bohr model draws gold as a nucleus of 79 protons and 118 neutrons, with its 79 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 18 in shell 5, 1 in shell 6. Press Build the atom to watch the shells fill from the inside out. The outer ring (the P shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of gold
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹ 4f¹⁴ 5d¹⁰
Short form (noble gas notation): [Xe] 6s¹ 4f¹⁴ 5d¹⁰. The [Xe] stands for the electrons of xenon, the noble gas before it.
Gold breaks the usual filling order. The Aufbau rule predicts 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁹, but experiments show the configuration above. Moving one electron from the s subshell gives a half-full or full d subshell, which is more stable.
How many valence electrons does gold have?
Gold has 1 valence electron.
Gold is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 1 electron in its outermost shell (shell 6), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 79 | equal to the atomic number |
|---|---|---|
| Electrons | 79 | equal to the protons in a neutral atom |
| Neutrons | 118 | mass number 197 − 79 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Gold properties
| Symbol | Au |
|---|---|
| Category | Transition metal |
| Group · period · block | 11 · 6 · d |
| Atomic mass | 196.97 u |
| State at 25 °C | solid |
| Melting point | 1,337 K (1,060 °C, 1,950 °F) |
| Boiling point | 3,129 K (2,860 °C, 5,170 °F) |
| Density | 19.282 g/cm³ |
| Electronegativity (Pauling) | 2.54 |
| Atomic radius | 166 pm |
| First ionization energy | 9.226 eV |
| Electron affinity | 2.309 eV |
| Oxidation states | +3, +1 |
| Common ion charge | +3, +1 |
| Discovered | Known since ancient times |
Where gold sits on the periodic table
Group 11: Copper, Silver, Roentgenium.
Questions about gold
How many valence electrons does gold have?
Gold has 1 valence electron in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does gold have?
A neutral gold atom has 79 protons and 79 electrons. Its most common form has about 118 neutrons (mass number 197 − 79 protons).
What is the electron configuration of gold?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹ 4f¹⁴ 5d¹⁰, written in short form as [Xe] 6s¹ 4f¹⁴ 5d¹⁰.
What does the Bohr model of gold look like?
A nucleus of 79 protons and 118 neutrons, circled by 6 electron shells holding 2, 8, 18, 32, 18, 1 electrons.
What is the atomic number of gold?
79. The atomic number is the number of protons in the nucleus, and it is what makes an atom gold.