Classification of Radium
Radium is an element identified by atomic number 88. Its position within the periodic table provides insight into its fundamental nature.
Group and Category
Radium is classified as an alkaline earth metal. It belongs to Group 2 of the periodic table, alongside elements like Beryllium, Magnesium, Calcium, Strontium, and Barium. This classification signifies its metallic properties and tendency to form positive ions in chemical reactions.
Macroscopic Physical Characteristics
The observable attributes of Radium provide information about its physical state and appearance under typical conditions.
Appearance and State at Room Temperature
At standard room temperature (approximately 25 °C) and atmospheric pressure, Radium exists as a solid. When freshly prepared and in its pure form, Radium displays a bright, silvery-white metallic luster. However, upon exposure to air, it undergoes rapid tarnishing, quickly developing a black layer due to reaction with nitrogen to form radium nitride (Ra₃N₂) or with oxygen to form radium oxide (RaO). This quick discoloration obscures its intrinsic silvery appearance.
Texture
Radium is characterized as a soft metal. Its malleability and ductility are properties typical of metals, though its extreme radioactivity prevents direct tactile examination under normal circumstances.
Thermal Properties
The temperatures at which Radium transitions between states of matter are specific indicators of its physical behavior.
Melting and Boiling Points
Radium exhibits a melting point of approximately 700 °C. The element transitions from a solid to a liquid state at this temperature. Its boiling point, the temperature at which it converts from a liquid to a gaseous state, is approximately 1737 °C. These thermal properties place Radium among metals with moderately high melting and boiling points.