Name: argon
Symbol: Ar
Atomic number: 18
Atomic weight: 39.948 (1) g r
Group in periodic table: 18
Group name: Noble gas
Period in periodic table: 3
Block in periodic table: p-block
CAS registry ID: 7440-37-1
Argon is colourless and odourless. Argon is very inert and is not known to form true chemical compounds. It makes a good atmosphere for working with air-sensitive materials since it is heavier than air and less reactive than N2.