Cl

Chlorine

Chlorine is a chemical element with symbol Cl and atomic number 17. It also has a relative atomic mass of 35.5. Chlorine is in the halogen group (17) and is the second lightest halogen following fluorine.

Group	diatomic nonmetal
Atomic number	17
Period	3
Group	17
Phase (STP)	Gas
Atomic mass	35.45
Density (STP)	3.2 g/L
Melting Point	171.6 K
Molar heat capacity
Boiling point	239.11 K
Discovered by	Carl Wilhelm Scheele undefined
Named by
Protons	17
Neutrons	18
Electrons	17
Valencia electrons	7

https://en.wikipedia.org/wiki/Chlorine