Periodic Table/Radium
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88Ra226 Da

Radium

Alkaline Earth Metal·Period 7, Group 2·s-block

Radioactive metallic transuranic element, belongs to group 2 of the periodic table. Most stable isotope, Ra-226 has a half-life of 1602 years, which decays into radon. Isolated from pitchblende in 1898 Marie and Pierre Curie.

Gallery

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

Bohr model of Radium

Physical Propertiesmass · density · phase · crystal

Atomic Mass

226Da

Density

5g/cm³

Phase (STP)

Solid

Melting Point

969.1K

Boiling Point

—

Molar Heat

—

Crystal Structure

—

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

215.00pm

Covalent

201.00pm

Van der Waals

283.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Rn] 7s2

Electron Shells

2, 8, 18, 32, 18, 8, 2

Electronegativity

0.90Pauling

Electron Affinity

0.1kJ/mol

1st Ionization Energy

5.3kJ/mol

Oxidation States

+2

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑↓
↑↓
↑↓
3d10
↑↓
4s2
↑↓
↑↓
↑↓
4p6
↑↓
↑↓
↑↓
↑↓
↑↓
4d10
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
4f14
↑↓
5s2
↑↓
↑↓
↑↓
5p6
↑↓
↑↓
↑↓
↑↓
↑↓
5d10
↑↓
6s2
↑↓
↑↓
↑↓
6p6
↑↓
7s2

Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s2Short: [Rn] 7s2

Ionization Energies (88 known)

1st5.3 kJ/mol2nd10.1 kJ/mol3rd31.0 kJ/mol4th41.0 kJ/mol5th52.9 kJ/mol6th64.0 kJ/mol7th82.0 kJ/mol8th97.0 kJ/mol9th124.0 kJ/mol10th140.0 kJ/mol11th204.9 kJ/mol12th227.0 kJ/mol13th250.0 kJ/mol14th274.0 kJ/mol15th299.0 kJ/mol16th324.0 kJ/mol17th356.0 kJ/mol18th382.0 kJ/mol19th409.0 kJ/mol20th435.0 kJ/mol21th570.0 kJ/mol22th600.0 kJ/mol23th630.0 kJ/mol24th660.0 kJ/mol25th740.0 kJ/mol26th770.0 kJ/mol27th860.0 kJ/mol28th900.0 kJ/mol29th970.0 kJ/mol30th1040.0 kJ/mol31th1110.0 kJ/mol32th1180.0 kJ/mol33th1250.0 kJ/mol34th1320.0 kJ/mol35th1390.0 kJ/mol36th1460.0 kJ/mol37th1530.0 kJ/mol38th1610.0 kJ/mol39th1680.0 kJ/mol40th1750.0 kJ/mol41th1820.0 kJ/mol42th1880.0 kJ/mol43th2208.0 kJ/mol44th2271.0 kJ/mol45th2338.0 kJ/mol46th2409.0 kJ/mol47th2477.0 kJ/mol48th2544.0 kJ/mol49th2662.0 kJ/mol50th2731.0 kJ/mol51th2806.0 kJ/mol52th2876.0 kJ/mol53th3155.0 kJ/mol54th3224.0 kJ/mol55th3298.0 kJ/mol56th3368.0 kJ/mol57th3682.0 kJ/mol58th3762.0 kJ/mol59th3959.0 kJ/mol60th4040.0 kJ/mol61th6565.0 kJ/mol62th6718.0 kJ/mol63th6881.0 kJ/mol64th7056.0 kJ/mol65th7222.0 kJ/mol66th7380.0 kJ/mol67th7720.0 kJ/mol68th7890.0 kJ/mol69th8080.0 kJ/mol70th8250.0 kJ/mol71th8730.0 kJ/mol72th8880.0 kJ/mol73th9040.0 kJ/mol74th9200.0 kJ/mol75th10190.0 kJ/mol76th10360.0 kJ/mol77th10720.0 kJ/mol78th10890.0 kJ/mol79th22900.0 kJ/mol80th23300.0 kJ/mol81th23750.0 kJ/mol82th24160.0 kJ/mol83th27830.0 kJ/mol84th28370.0 kJ/mol85th29050.0 kJ/mol86th29479.8 kJ/mol87th116853.5 kJ/mol88th118929.5 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

483
714
468
Ra emission
380nm750nm
482.6 nm(100%)714.0 nm(50%)468.2 nm(40%)

Abundanceby mass

🌍Earth's Crust
900.0 ppt
🌊Ocean
1.0e-10 ppm
✨Universe—
🧬Human Body
1.0e-8 ppm

Log scale · ppm = parts per million by mass

Biological Role

Toxic

Radioactive. Mimics calcium and incorporates into bones, causing bone cancer.

Discovery

Discovered By

Pierre and Marie Curie

Named By

—

Year

1898

Nuclear Data

Known Isotopes

35

Stable Isotopes

0

Stable Mass Numbers

None

Isotopes of Ra35 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
201Ra88113201.01281520.0 msα (1%)3/2-—
202Ra88114202.0097424.10 msα (1%)0+—
203Ra88115203.00923436.0 msα (1%), β⁺3/2-—
233Ra88145233.04759530.0 sβ⁻ (1%)1/2+—
234Ra88146234.05038230.0 sβ⁻ (1%), β⁻SF0+—
235Ra88147235.054890Unknownβ⁻5/2+—

Click any isotope for its full page with decay chain:

201Ra202Ra203Ra204Ra205Ra206Ra207Ra208Ra209Ra210Ra211Ra212Ra213Ra214Ra215Ra216Ra217Ra218Ra219Ra220Ra221Ra222Ra223Ra224Ra225Ra226Ra227Ra228Ra229Ra230Ra231Ra232Ra233Ra234Ra235Ra
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