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).
It belongs to group 2 of the periodic table having trivial name alkaline earth metals*.
Radium Facts
Read key information and facts about element Radium
Name | Radium |
Atomic Number | 88 |
Atomic Symbol | Ra |
Atomic Weight | 226 |
Phase | Solid |
Color | Silver |
Appearance | silvery white metallic |
Classification | Alkaline Earth Metal |
Group in Periodic Table | 2 |
Group Name | beryllium family |
Period in Periodic Table | period 7 |
Block in Periodic Table | s -block |
Electronic Configuration | [Rn] 7s2 |
Electronic Shell Structure (Electrons per shell) | 2, 8, 18, 32, 18, 8, 2 |
Melting Point | 973 K |
Boiling Point | 2010 K |
CAS Number | CAS7440-14-4 |
How to Locate Radium on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 88 to find Radium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Radium on periodic table look for cross section of group 2 and period 7 in the modern periodic table.
Radium History
The element Radium was discovered by P. and M. Curie in year 1898 in France. Radium was first isolated by M. Curie in 1902. Radium derived its name from the Latin radius, 'ray'.
The Curies reported on December 26, 1898, a new element different from polonium, which Marie later isolated fromuraninite.
Radium Presence: Abundance in Nature and Around Us
The table below shows the abundance of Radium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
ppb by weight (1ppb =10^-7 %) | ppb by atoms (1ppb =10^-7 %) | |
---|---|---|
Abundance in Universe | - | - |
Abundance in Sun | - | - |
Abundance in Meteorites | - | - |
Abundance in Earth's Crust | 0.00010 | 0.00001 |
Abundance in Oceans | 0.00000001 | 0.0000000003 |
Abundance in Humans | 0.000001 | 0.00000003 |
Crystal Structure of Radium
The solid state structure of Radium is Body Centered Cubic.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
Unit Cell Parameters
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)
a | b | c |
---|---|---|
514.8 pm | 514.8 pm | 514.8 pm |
and the angles between them Lattice Angles (alpha, beta and gamma).
alpha | beta | gamma |
---|---|---|
π/2 | π/2 | π/2 |
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.
Space Group Name | Im_ 3m |
Space Group Number | 229 |
Crystal Structure | Body Centered Cubic |
Number of atoms per unit cell | 2 |

The number of atoms per unit cell in a simple cubic, face-centered cubic and body-centred cubic are 1,4,2 respectively.
Radium Atomic and Orbital Properties
Radium atoms have 88 electrons and the electronic shell structure is [2, 8, 18, 32, 18, 8, 2] with Atomic Term Symbol (Quantum Numbers) 1S0.
Atomic Number | 88 |
Number of Electrons (with no charge) | 88 |
Number of Protons | 88 |
Mass Number | 226 |
Number of Neutrons | 138 |
Shell structure (Electrons per energy level) | 2, 8, 18, 32, 18, 8, 2 |
Electron Configuration | [Rn] 7s2 |
Valence Electrons | 7s2 |
Valence (Valency) | 2 |
Main Oxidation States | 2 |
Oxidation States | 2 |
Atomic Term Symbol (Quantum Numbers) | 1S0 |
Bohr Atomic Model of Radium - Electrons per energy level

n | s | p | d | f |
---|
Ground State Electronic Configuration of Radium - neutral Radium atom
Abbreviated electronic configuration of Radium
The ground state abbreviated electronic configuration of Neutral Radium atom is [Rn] 7s2. The portion of Radium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Rn]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 7s2, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Radium
Complete ground state electronic configuration for the Radium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 7s2
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

Atomic Structure of Radium
Radium atomic radius is - , while it's covalent radius is - .
Atomic Radius Calculated | - (0 Å) |
Atomic Radius Empirical | 215 pm (2.15 Å) |
Atomic Volume | 41.09 cm3/mol |
Covalent Radius | - |
Van der Waals Radius | 283 pm |
Neutron Cross Section | 20 |
Neutron Mass Absorption | - |
Atomic Spectrum of Radium
Radium Chemical Properties: Radium Ionization Energies and electron affinity
The electron affinity of Radium is - .
Valence | 2 |
Electronegativity | 0.9 |
ElectronAffinity | - |
Ionization Energy of Radium
Refer to table below for Ionization energies of Radium
Ionization energy number | Enthalpy - kJ/mol |
---|---|
1st | 509.3 |
2nd | 979 |
Radium Physical Properties
Refer to below table for Radium Physical Properties
Density | 5 g/cm3 |
Molar Volume | 41.09 cm3/mol |
Elastic Properties
Young Modulus | - |
Shear Modulus | - |
Bulk Modulus | - |
Poisson Ratio | - |
Hardness of Radium - Tests to Measure of Hardness of Element
Mohs Hardness | - |
Vickers Hardness | - |
Brinell Hardness | - |
Radium Electrical Properties
Radium is Conductor of electricity. Refer to table below for the Electrical properties ofRadium
Electrical Conductivity | 1000000 S/m |
Resistivity | 0.000001 m Ω |
Superconducting Point | - |
Radium Heat and Conduction Properties
Thermal Conductivity | 19 W/(m K) |
Thermal Expansion | - |
Radium Magnetic Properties
Magnetic Type | - |
Curie Point | - |
Mass Magnetic Susceptibility | - |
Molar Magnetic Susceptibility | - |
Volume Magnetic Susceptibility | - |
Optical Properties of Radium
Refractive Index | - |
Acoustic Properties of Radium
Speed of Sound | - |
Radium Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Radium
Melting Point | 973 K (699.85°C, 1291.73 °F) |
Boiling Point | 2010 K (1736.85°C, 3158.33 °F) |
Critical Temperature | - |
Superconducting Point | - |
Enthalpies of Radium
Heat of Fusion | 8 kJ/mol |
Heat of Vaporization | 125 kJ/mol |
Heat of Combustion | - |
Radium Isotopes - Nuclear Properties of Radium
Radium has 33 isotopes, with between 202 and 234 nucleons. Radium has 0 stable naturally occuring isotopes.
Isotopes of Radium - Naturally occurring stable Isotopes: -.
Isotope | Z | N | Isotope Mass | % Abundance | T half | Decay Mode |
---|---|---|---|---|---|---|
202Ra | 88 | 114 | 202 | Synthetic | ||
203Ra | 88 | 115 | 203 | Synthetic | ||
204Ra | 88 | 116 | 204 | Synthetic | ||
205Ra | 88 | 117 | 205 | Synthetic | ||
206Ra | 88 | 118 | 206 | Synthetic | ||
207Ra | 88 | 119 | 207 | Synthetic | ||
208Ra | 88 | 120 | 208 | Synthetic | ||
209Ra | 88 | 121 | 209 | Synthetic | ||
210Ra | 88 | 122 | 210 | Synthetic | ||
211Ra | 88 | 123 | 211 | Synthetic | ||
212Ra | 88 | 124 | 212 | Synthetic | ||
213Ra | 88 | 125 | 213 | Synthetic | ||
214Ra | 88 | 126 | 214 | Synthetic | ||
215Ra | 88 | 127 | 215 | Synthetic | ||
216Ra | 88 | 128 | 216 | Synthetic | ||
217Ra | 88 | 129 | 217 | Synthetic | ||
218Ra | 88 | 130 | 218 | Synthetic | ||
219Ra | 88 | 131 | 219 | Synthetic | ||
220Ra | 88 | 132 | 220 | Synthetic | ||
221Ra | 88 | 133 | 221 | Synthetic | ||
222Ra | 88 | 134 | 222 | Synthetic | ||
223Ra | 88 | 135 | 223 | Synthetic | ||
224Ra | 88 | 136 | 224 | Synthetic | ||
225Ra | 88 | 137 | 225 | Synthetic | ||
226Ra | 88 | 138 | 226 | Synthetic | 1.59×10^3 years | AlphaEmission |
227Ra | 88 | 139 | 227 | Synthetic | ||
228Ra | 88 | 140 | 228 | Synthetic | ||
229Ra | 88 | 141 | 229 | Synthetic | ||
230Ra | 88 | 142 | 230 | Synthetic | ||
231Ra | 88 | 143 | 231 | Synthetic | ||
232Ra | 88 | 144 | 232 | Synthetic | ||
233Ra | 88 | 145 | 233 | Synthetic | ||
234Ra | 88 | 146 | 234 | Synthetic |
Regulatory and Health - Health and Safety Parameters and Guidelines
Database Search
List of unique identifiers to search the element in various chemical registry databases
Database | Identifier number |
---|---|
CAS Number - Chemical Abstracts Service (CAS) | CAS7440-14-4 |
RTECS Number | - |
CID Number | CID6328144 |
Gmelin Number | Gmelin40437 |
NSC Number | - |
Compare Radium with other elements
Compare Radium with all Group 2 elements
Compare Radium with all Period 7 elements
Compare Radium with all Alkaline Earth Metal elements
FAQs
What is the electronic configuration of Radium?
The electronic configuration of Radium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 7s2.
What is the abbreviated electronic configuration of Radium?
The abbreviated electronic configuration of Radium is [Rn] 7s2. To form abbreviated notation of electronic configuration, the completely filled subshells are replaced by the noble gas of the preceding period in square brackets.
What is the symbol of Radium?
Symbol of Radium is Ra. Radium is a chemical element with symbol Ra and atomic number 88.
What is the position of Radium in the Periodic Table?
Radium is a chemical element with the symbol Ra and atomic number 88. Radium is the 88 element on the periodic table. It is located in group 2 and period 7 in the modern periodic table.
What is the atomic number of Radium?
The atomic number of Radium is 88.
What is the color of Radium?
Radium is of Silver color.
Who discovered Radium?
The element Radium was discovered by P. and M. Curie in year 1898 in France. Radium was first isolated by M. Curie in 1902.
How many valence electrons does a Radium atom have?
Radium has 2 valence electrons. Radium has 88 electrons out of which 2 valence electrons are present in the 7s2 outer orbitals of atom.
What is the melting Point of Radium?
Melting Point of Radium is 973 K.
What is the boiling Point of Radium?
Boiling Point of Radium is 2010 K.
What is the melting Point of Radium in Kelvin?
Melting Point of Radium in Kelvin is 973 K.
What is the boiling Point of Radium in Kelvin?
Boiling Point of Radium in Kelvin is 2010 K.
What is the electronic configuration of Radium 88?
The electronic configuration of Radium will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 7s2.
How do you write the electron configuration for Radium?
The electronic configuration of Radium will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 7s2.