Lanthanum
Lanthanum is a soft, ductile, silvery-white metallic chemical element with symbol La and atomic number 57. It tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It gave its name to the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table:it is also sometimes considered the first element of the 6th-period transition metals.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
54 is the [Xe] core total across five shells.
At a glance
- Atomic number
- 57
- Atomic mass
- 138.905477 u
- Phase
- Solid
- Density
- 6.162 g/cm³
- Melting point
- 1,193 K
- Boiling point
- 3,737 K
- First ionization energy
- 538.1 kJ/mol
- Electronegativity
- 1.1
- Electron affinity
- 53 kJ/mol
- Molar heat capacity
- 27.11 J/(mol·K)
- Period
- 6
- Appearance
- silvery white
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
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