Radium (Ra)
The curie, an old unit of radioactivity, was originally based on the activity of one gram of radium-226.
Radium properties
- Atomic mass
- 226 u
- Category
- Alkaline earth metal
- Group
- 2
- Period
- 7
- Block
- s-block
- State at room temp.
- Solid
- Melting point
- 973 K (699.8 °C)
- Boiling point
- 2,010 K (1,736.8 °C)
- Density
- 5.5 g/cm³
- Atomic radius
- 283 pm
- Ionization energy
- 5.279 eV
- Electron affinity
- —
- Radioactive
- Yes, no stable isotopes
- Discovered
- 1898
Radium electron configuration
- Electron configuration
- [Rn] 7s2
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s2
- Electron shells
- 2 · 8 · 18 · 32 · 18 · 8 · 2
The electron configuration of Radium (Ra) is [Rn] 7s2. Its 88 electrons are arranged in shells as 2, 8, 18, 32, 18, 8, 2.
Protons, neutrons and electrons in Radium
A neutral Radium atom has 88 protons and 88 electrons. Most Radium atoms have about 138 neutrons: the atomic mass rounded to 226, minus the atomic number 88.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Radium have?
2
Radium has 2 valence electrons in its outermost shell, shell 7. These are the electrons involved in chemical bonding.
Radium 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 Radium
226 g/mol
One mole of Radium atoms (6.022 × 10²³ atoms) has a mass of 226 grams. Use this value to convert between grams and moles.
Radium facts
- The curie, an old unit of radioactivity, was originally based on the activity of one gram of radium-226.
- Marie Curie and André-Louis Debierne first isolated pure radium metal in 1910.
- Radium (Ra) has atomic number 88 and is a solid at room temperature. It was discovered in 1898.
Position in the periodic table
Radium is element 88, in period 7 and group 2 of the periodic table, in the s-block.
Uses of Radium
Radium is rarely used today because safer radioactive sources have replaced it. It once made glowing paint for watch dials and aircraft instruments and was used in early cancer treatment. Today the isotope radium-223 is given as a medicine for prostate cancer that has spread to the bones, because radium behaves chemically like calcium and collects in bone.
Who discovered Radium?
Marie and Pierre Curie, working with Gustave Bémont, announced the discovery of radium in Paris in 1898 after finding a new radioactive substance in pitchblende ore. The name comes from the Latin radius, meaning 'ray'.
Where does the name come from?
Radium comes from the Latin radius, meaning 'ray'. Marie and Pierre Curie named it in 1898 for the intense radiation it gives off, which can make its compounds glow faintly in the dark.
Same group
Compare Radium
FAQ
What is the electron configuration of Radium?
The electron configuration of Radium (Ra) is [Rn] 7s2. Its 88 electrons are arranged in shells as 2, 8, 18, 32, 18, 8, 2.
How many protons, neutrons and electrons does Radium have?
A neutral Radium atom has 88 protons and 88 electrons. Most Radium atoms have about 138 neutrons: the atomic mass rounded to 226, minus the atomic number 88.
How many valence electrons does Radium have?
Radium has 2 valence electrons in its outermost shell, shell 7. These are the electrons involved in chemical bonding.
What is the molar mass of Radium?
The molar mass of Radium is 226 g/mol. This is the same number as its atomic mass, 226 u.
Is Radium a metal?
Yes. Radium is an alkaline earth metal, so it is a metal.
Is Radium radioactive?
Yes. Radium has no stable isotopes, so all of its atoms are radioactive and eventually decay into other elements.
Where is Radium on the periodic table?
Radium is element 88, in period 7 and group 2 of the periodic table, in the s-block.