Antimony (Sb)
Antimony is element 51, a metalloid in group 15, period 5. A neutral atom has 51 protons, 71 neutrons and 51 electrons, 5 of them valence electrons.
Metalloid- Atomic number
- 51
- Atomic mass
- 121.76 u
- Valence electrons
- 5
- Protons · neutrons
- 51 · 71
- Electrons per shell
- 2, 8, 18, 18, 5
- At room temperature
- solid
Bohr model of antimony
The Bohr model draws antimony as a nucleus of 51 protons and 71 neutrons, with its 51 electrons on 5 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 18 in shell 4, 5 in shell 5. Press Build the atom to watch the shells fill from the inside out. The outer ring (the O 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 antimony
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p³
Short form (noble gas notation): [Kr] 5s² 4d¹⁰ 5p³. The [Kr] stands for the electrons of krypton, the noble gas before it.
How many valence electrons does antimony have?
Antimony has 5 valence electrons.
Antimony is in group 15, and for groups 13–18 you subtract 10 from the group number: 15 − 10 = 5. It tends to share electrons in covalent bonds.
Protons, neutrons and electrons
| Protons | 51 | equal to the atomic number |
|---|---|---|
| Electrons | 51 | equal to the protons in a neutral atom |
| Neutrons | 71 | mass number 122 − 51 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.
Antimony properties
| Symbol | Sb |
|---|---|
| Category | Metalloid |
| Group · period · block | 15 · 5 · p |
| Atomic mass | 121.76 u |
| State at 25 °C | solid |
| Melting point | 903.8 K (631 °C, 1,170 °F) |
| Boiling point | 1,860 K (1,590 °C, 2,890 °F) |
| Density | 6.685 g/cm³ |
| Electronegativity (Pauling) | 2.05 |
| Atomic radius | 206 pm |
| First ionization energy | 8.64 eV |
| Electron affinity | 1.07 eV |
| Oxidation states | +5, +3, −3 |
| Common ion charge | +5, +3 |
| Discovered | Known since ancient times |
Where antimony sits on the periodic table
Group 15: Nitrogen, Phosphorus, Arsenic, Bismuth, Moscovium.
Questions about antimony
How many valence electrons does antimony have?
Antimony has 5 valence electrons.
How many protons, neutrons and electrons does antimony have?
A neutral antimony atom has 51 protons and 51 electrons. Its most common form has about 71 neutrons (mass number 122 − 51 protons).
What is the electron configuration of antimony?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p³, written in short form as [Kr] 5s² 4d¹⁰ 5p³.
What does the Bohr model of antimony look like?
A nucleus of 51 protons and 71 neutrons, circled by 5 electron shells holding 2, 8, 18, 18, 5 electrons.
What is the atomic number of antimony?
51. The atomic number is the number of protons in the nucleus, and it is what makes an atom antimony.