Metallic bonds - valence electrons are distributed throughout a metallic crystal.
Valence electrons in metals can be thought of as being property of all the atoms in the crystal.
The positive nuclei are surrounded by a "sea" of valence electrons that are attracted equally by several nuclei.
This characteristic makes metals good conductors of heat and electricity.
Hydrogen bonds - a special type of bond between a hydrogen atom in a covalently bonded molecule and an unshared electron in a nearby molecule. Since the hydrogen atom is so small, it can get very close to other atoms - causing electrons in those atoms to be attracted to it.
This is especially important with small, polar molecules like water.
20 things you didn't know about water
Hydrogen bonding is responsible for the very high specific heat capacity (ability to absorb large amounts of heat with little temperature change) of water, its relatively high boiling point, for water often being called the universal solvent, and for the formation of water clusters.
This is especially important with small, polar molecules like 
Hydrogen bonding is responsible for the very high specific heat capacity (ability to absorb large amounts of heat with little temperature change) of water, its relatively high boiling point, for water often being called the universal solvent, and for the formation of 
Combined Volumes
