Cobalt (Co)
Cobalt's name comes from the German word Kobold, a goblin that miners blamed for ores that gave off poisonous fumes and yielded no useful metal.
Cobalt properties
- Atomic mass
- 58.933 u
- Category
- Transition metal
- Group
- 9
- Period
- 4
- Block
- d-block
- State at room temp.
- Solid
- Electronegativity
- 1.88
- Melting point
- 1,768 K (1,494.8 °C)
- Boiling point
- 3,200 K (2,926.8 °C)
- Density
- 8.9 g/cm³
- Common charges
- +2, +3
- Oxidation states
- +3, +2
- Atomic radius
- 192 pm
- Ionization energy
- 7.881 eV
- Electron affinity
- 0.661 eV
- Radioactive
- No, has stable isotopes
- Discovered
- 1735
Cobalt electron configuration
- Electron configuration
- [Ar] 3d7 4s2
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d7 4s2
- Electron shells
- 2 · 8 · 15 · 2
The electron configuration of Cobalt (Co) is [Ar] 3d7 4s2. Its 27 electrons are arranged in shells as 2, 8, 15, 2.
Protons, neutrons and electrons in Cobalt
A neutral Cobalt atom has 27 protons and 27 electrons. Most Cobalt atoms have about 32 neutrons: the atomic mass rounded to 59, minus the atomic number 27.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Cobalt have?
2
Cobalt has 2 valence electrons, counting the electrons in its outermost s subshell. Like most transition metals, it can also use d electrons in bonding.
Cobalt orbital diagram
Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations
Molar mass of Cobalt
58.933 g/mol
One mole of Cobalt atoms (6.022 × 10²³ atoms) has a mass of 58.933 grams. Use this value to convert between grams and moles.
Compounds containing Cobalt
Cobalt facts
- Cobalt's name comes from the German word Kobold, a goblin that miners blamed for ores that gave off poisonous fumes and yielded no useful metal.
- A cobalt atom sits at the center of vitamin B12, which the body needs to make red blood cells and keep nerves healthy.
- Cobalt (Co) has atomic number 27 and is a solid at room temperature. It was discovered in 1735.
Position in the periodic table
Cobalt is element 27, in period 4 and group 9 of the periodic table, in the d-block.
Uses of Cobalt
Cobalt is a key ingredient in the cathodes of many lithium-ion batteries for phones, laptops and electric cars. It is used in superalloys for jet engines and gas turbines because it stays strong at high temperatures, and in powerful permanent magnets. Cobalt compounds have colored glass and ceramics deep blue for centuries, and radioactive cobalt-60 is used to treat cancer and sterilize medical equipment.
Who discovered Cobalt?
Swedish chemist Georg Brandt identified cobalt in about 1735 while studying why certain ores gave glass a deep blue color. He showed that the color came from a new metal, not from bismuth as was then believed.
Where does the name come from?
Cobalt comes from the German Kobold, meaning 'goblin'. Miners blamed mischievous goblins for ores that looked valuable but yielded no useful metal and gave off poisonous arsenic fumes when smelted.
Same group
Compare Cobalt
FAQ
What is the electron configuration of Cobalt?
The electron configuration of Cobalt (Co) is [Ar] 3d7 4s2. Its 27 electrons are arranged in shells as 2, 8, 15, 2.
How many protons, neutrons and electrons does Cobalt have?
A neutral Cobalt atom has 27 protons and 27 electrons. Most Cobalt atoms have about 32 neutrons: the atomic mass rounded to 59, minus the atomic number 27.
How many valence electrons does Cobalt have?
Cobalt has 2 valence electrons, counting the electrons in its outermost s subshell. Like most transition metals, it can also use d electrons in bonding.
What is the molar mass of Cobalt?
The molar mass of Cobalt is 58.933 g/mol. This is the same number as its atomic mass, 58.933 u.
Is Cobalt a metal?
Yes. Cobalt is a transition metal, so it is a metal.
Is Cobalt radioactive?
Ordinary Cobalt is not radioactive: it has at least one stable isotope. Like every element, it also has radioactive isotopes, most of them made in laboratories.
Where is Cobalt on the periodic table?
Cobalt is element 27, in period 4 and group 9 of the periodic table, in the d-block.