Which of the following statement is correct?

I. On combustion in excess of air, lithium forms mainly the oxide.

II. The alkali metal halides are all high-melting, colorless crystalline liquids.

The correct answer is Only I.

Key Points

• Lithium upon reaction with excess air usually forms lithium oxide but lithium peroxide is also possible to form.
• But we know that peroxides upon hydrolysis give hydrogen peroxide and metal hydroxide.
• The reaction between lithium and oxygen is 4Li + O₂→2Li₂O.
• The alkali metal halides exist as colourless crystalline solids, although as finely ground powders appear white.
• They melt at high temperature, usually several hundred degrees to colorless liquids.
• Their high melting point reflects their high lattice energy.

Additional Information

• Alkali Metal:
  • Alkali metal form a part of the leftmost group, i.e. group 1 of the ultramodern periodic table.
  • It contains six rudiments, which are collaboratively called the Lithium family.
  • These essence are largely reactive essence of the periodic table due to the presence of one electron in their remotest shell, called the valence electron.
• Alkaline Earth Metal:
  • Elements whose atoms have their s-subshell filled with their two valence electrons are called alkaline earth metals.
  • Their general electronic configuration is [Noble gas] ns2.
  • They occupy the second column of the periodic table and so-called as group two metals also.