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88 Ra Radium 226

Radium

ALKALINE EARTH METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.

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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Quick Facts

Atomic Number 88
Period 7
Group 2
Phase Solid
Appearance silvery white metallic
About Alkaline Earth Metals

Alkaline earth metals (Group 2) are reactive metals, though less so than alkali metals. They typically lose two electrons to form cations with a +2 charge.

History

Discovered By Pierre Curie
Named By Unknown

Physical Properties

Atomic Mass 226
Density 5.5 g/L
Molar Heat N/A J/(mol·K)
Phase Transition (Melting & Boiling Points)

Radium melts at 1233 K and boils at 2010 K.

Atomic Properties

Electron Config [Rn] 7s2
Electronegativity 0.9
Electron Affinity 9.6485 kJ/mol
Ionization Energy 509.3 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.

Photograph

Image of Radium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.