Ra

Radium · element 88

Alkaline Earth Metal · Solid at room temperature

Radium is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is almost colorless, but it readily combines with nitrogen (rather than oxygen) on exposure to air, forming a black surface layer of radium nitride (Ra3N2).

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Radium electroplated on a very small sample of copper foil and covered with polyurethane to prevent reaction with the air
Radium electroplated on a very small sample of copper foil and covered with polyurethane to prevent reaction with the air - grenadier, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Key facts

Atomic mass
226 u
how heavy one atom is
Phase (room temp.)
Solid
Density
5.5 g/cm³
how tightly packed it is
Melting point
1233 K (960 °C)
when solid turns to liquid
Boiling point
2010 K (1737 °C)
when liquid turns to gas
Period
7
its row in the periodic table
Group
2
its column in the periodic table
Block
S-block
the neighbourhood it lives in
Electronegativity
0.9
how strongly it pulls electrons
Electron configuration
[Rn] 7s2
where its electrons live
Shells
2 · 8 · 18 · 32 · 18 · 8 · 2
electrons in each layer, inside to out
Discovered by
Pierre Curie
who found it
Appearance
silvery white metallic
what it looks like

Source: Wikipedia

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