Atomic number 10, this odorless gaseous element is obtained from fractional distillation of liquid air
... Atomic number 10; atomic weight 20.180; melting point -248.59C; 
boiling point ... a colourless odourless rare gaseous element, an inert gas 
occurring in trace... [DOC] [TLE] krypton Facts, information, pictures | Encyclopedia.com articles ... [PAR] The missing noble gases had atomic numbers 10, 36, 54, and 86.