18 Ar 39.9481

Argon

NOBLE GAS

Phase: Gas

Discovered: Lord Rayleigh

Block: P

Summary

Argon is a chemical element with symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most common gas in the Earth's atmosphere, at 0.934% (9,340 ppmv), making it over twice as abundant as the next most common atmospheric gas, water vapor (which averages about 4000 ppmv, but varies greatly), and 23 times as abundant as the next most common non-condensing atmospheric gas, carbon dioxide (400 ppmv), and more than 500 times as abundant as the next most common noble gas, neon (18 ppmv).

Appearance: colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field

Source: Wikipedia

Physical Properties

Atomic Mass 39.9481 u

Density 1.784 g/cm³

Melting Point 83.81 K

Boiling Point 87.302 K

Molar Heat N/A

Electron Affinity -96 kJ/mol

Ionization Energies

1^st: 1520.6 kJ/mol

2^nd: 2665.8 kJ/mol

3^rd: 3931 kJ/mol

4^th: 5771 kJ/mol

5^th: 7238 kJ/mol

6^th: 8781 kJ/mol

7^th: 11995 kJ/mol

8^th: 13842 kJ/mol

9^th: 40760 kJ/mol

10^th: 46186 kJ/mol

11^th: 52002 kJ/mol

12^th: 59653 kJ/mol

13^th: 66199 kJ/mol

14^th: 72918 kJ/mol

15^th: 82473 kJ/mol

16^th: 88576 kJ/mol

17^th: 397605 kJ/mol

18^th: 427066 kJ/mol