Lithium (Li)
Lithium is the 3rd element, a alkali metal in the s-block. Its standard atomic weight is 6.941.
Lithium
6.941
What the table records
- Atomic number
- 3
- Standard atomic weight
- 6.941
- Group
- 1
- Period
- 2
- Block
- s-block
- Category
- Alkali metal
- [He] 2s1
- Valence electrons
- 1
- Typical valence
- 1
- Van der Waals radius
- 2.2 Å
- Covalent radius
- 1.28 Å
Molecules containing lithium
The lightest named structures in this library that contain Li.
Lithium
Li · 6.94 g/mol
Lithium ion
Li+ · 6.94 g/mol
Lithium aluminum hydride
H₄AlLi · 37.96 g/mol
Lithium, 1-propynyl-
C₃H₃Li · 46 g/mol
Butyllithium
C₄H₉Li · 64.06 g/mol
Tert-Butyllithium
C₄H₉Li · 64.06 g/mol
lithium acetate
C₂H₃LiO₂ · 65.99 g/mol
Lithium Carbonate
CLi₂O₃ · 73.89 g/mol
lithium 2-methylpropan-2-olate
C₄H₉LiO · 80.06 g/mol
Phenyllithium
C₆H₅Li · 84.05 g/mol
Lithium trimethylsilanolate
C₃H₉LiOSi · 96.13 g/mol
Lithium diisopropylamide
C₆H₁₄LiN · 107.13 g/mol
How to read these numbers
The standard atomic weight is an average over the isotopes as they occur naturally, which is why it is rarely a whole number. It is the figure a molar mass calculation uses. Work in mass spectrometry wants the monoisotopic mass of a single isotope instead, which is a different number.
The two radii are not the same measurement. The covalent radius is half the distance between two bonded atoms of the element; the van der Waals radius is how close a non-bonded atom gets before repulsion takes over, and is always the larger. Space-filling models are drawn with the second, ball-and-stick models with the first — which is why the same molecule looks so different in the two.