9 . Physical properties of dihydrogen Hydrogen is a colorless , odorless and a tasteless gas Hydrogen is highly combustible Hydrogen is lighter than air Hydrogen is insoluble in water
10 . The binary compounds of hydrogen with other elements are called hydrides
11 . Ionic hydrides or Saline hydrides are binary compounds of hydrogen with s- block elements which are highly electropositive
12 . Covalent or molecular hydrides are binary compounds of hydrogen with elements of comparatively high electronegativity such as p-block elements
13 . Covalent hydrides are classified as electron rich , electron deficient or electron precise hydrides
Electron rich hydrides have excess electrons than required to form normal covalent bonds . Excess electrons are present as lone pairs . Examples of this are hydrides of group 15 , 16 and 17 such as ammonia , water etc .
Electron deficient hydrides do not have sufficient number of electrons to form normal covalent bonds . Examples of this are hydrides of group 13
Electron precise hydrides have required number of electrons to write the conventional Lewis structure . Elements of group 14 like carbon , silicon etc . form these types of hydrides
14 . Metallic hydrides or Interstitial hydrides are the compounds of hydrogen with transition metals of group 3,4,5 of d-block , Cr metal of group 6 , f-block element
15 . Since the composition of metallic hydrides does not correspond to simple whole number ratio they are also called non-stoichiometric hydrides
16 . Due to high polarity , water dissolves most of the polar substances
17 . Due to hydrogen bonding water has high boiling point and high heat of vaporization
18 . Density of water is more than that of ice