Platinum (Pt)
Platinum is element 78, a transition metal in group 10, period 6. A neutral atom has 78 protons, 117 neutrons and 78 electrons, 1 of them valence electrons.
Transition metal- Atomic number
- 78
- Atomic mass
- 195.08 u
- Valence electrons
- 1*
- Protons · neutrons
- 78 · 117
- Electrons per shell
- 2, 8, 18, 32, 17, 1
- At room temperature
- solid
Bohr model of platinum
The Bohr model draws platinum as a nucleus of 78 protons and 117 neutrons, with its 78 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 17 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 platinum
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹ 4f¹⁴ 5d⁹
Short form (noble gas notation): [Xe] 6s¹ 4f¹⁴ 5d⁹. The [Xe] stands for the electrons of xenon, the noble gas before it.
Platinum breaks the usual filling order. The Aufbau rule predicts 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁸, but experiments show the configuration above. The energy levels of the subshells are so close here that a different arrangement wins.
How many valence electrons does platinum have?
Platinum has 1 valence electron.
Platinum 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 | 78 | equal to the atomic number |
|---|---|---|
| Electrons | 78 | equal to the protons in a neutral atom |
| Neutrons | 117 | mass number 195 − 78 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.
Platinum properties
| Symbol | Pt |
|---|---|
| Category | Transition metal |
| Group · period · block | 10 · 6 · d |
| Atomic mass | 195.08 u |
| State at 25 °C | solid |
| Melting point | 2,042 K (1,770 °C, 3,220 °F) |
| Boiling point | 4,098 K (3,820 °C, 6,920 °F) |
| Density | 21.46 g/cm³ |
| Electronegativity (Pauling) | 2.28 |
| Atomic radius | 209 pm |
| First ionization energy | 9 eV |
| Electron affinity | 2.128 eV |
| Oxidation states | +4, +2 |
| Common ion charge | +4, +2 |
| Discovered | 1735 by Antonio de Ulloa |
Where platinum sits on the periodic table
Group 10: Nickel, Palladium, Darmstadtium.
Questions about platinum
How many valence electrons does platinum have?
Platinum has 1 valence electron in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does platinum have?
A neutral platinum atom has 78 protons and 78 electrons. Its most common form has about 117 neutrons (mass number 195 − 78 protons).
What is the electron configuration of platinum?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹ 4f¹⁴ 5d⁹, written in short form as [Xe] 6s¹ 4f¹⁴ 5d⁹.
What does the Bohr model of platinum look like?
A nucleus of 78 protons and 117 neutrons, circled by 6 electron shells holding 2, 8, 18, 32, 17, 1 electrons.
What is the atomic number of platinum?
78. The atomic number is the number of protons in the nucleus, and it is what makes an atom platinum.