Sodium melts at 98 °C, and magnesium melts at 650 °C. Account for the higher melting point of magnesium using the electron-sea model.

Key Concepts

Electron-Sea Model

The electron-sea model describes metallic bonding as a structure where electrons are delocalized and free to move throughout a lattice of positively charged metal ions. This 'sea' of electrons allows metals to conduct electricity and contributes to their malleability and ductility. The strength of the metallic bond, influenced by the number of delocalized electrons, plays a crucial role in determining the melting point of metals.

Metallic Bonding Strength

The strength of metallic bonds varies among different metals, primarily due to the number of valence electrons that can participate in the electron-sea. Magnesium, with its two valence electrons, forms stronger metallic bonds compared to sodium, which has one. This increased bonding strength in magnesium results in a higher melting point, as more energy is required to overcome these bonds during the melting process.

Melting Point and Atomic Structure

The melting point of a substance is influenced by its atomic structure and the type of bonding present. In metals, a higher melting point typically indicates stronger metallic bonds and a more stable lattice structure. Magnesium's higher melting point compared to sodium can be attributed to its greater atomic mass and the stronger interactions between its ions and the delocalized electrons, leading to a more stable arrangement that requires more energy to disrupt.