Argon (Ar) VS Krypton (Kr)
A definitive side-by-side comparison of two essential element profiles.
VS
Main Differences
Argon (Ar) is an element in the noble gases category with an atomic number of 18. Krypton (Kr) is an element in the noble gases category with an atomic number of 36.
Krypton (Kr) is 2.1x denser than Argon (Ar). However, Krypton (Kr) melts at a higher temperature than Argon (Ar) (a difference of 32.0 Kelvin).
Where do the names come from?
Ar Argon (Ar) Naming History
The name Argon is derived from the Greek, ''argos'', meaning idle.
Kr Krypton (Kr) Naming History
The name Krypton is derived from the Greek ''kryptos'', meaning hidden.
Related Comparisons
Compare
Argon (Ar)
Krypton (Kr)
Category
Noble Gases
Noble Gases
Atomic Number
18
36
Symbol
Ar
Kr
Atomic Mass
39.95 u
83.798 u
Group
18
18
Period
3
4
Block
p-block
p-block
Standard State (at 20°C)
gas
gas
Density
1.784 g/L g/cm³
3.749 g/L g/cm³
Melting Point (°C)
−189.34°C
−157.37°C
Melting Point (°F)
−308.81°F
−251.27°F
Melting Point (K)
83.8 K
115.79 K
Boiling Point (°C)
−185.848°C
−153.415°C
Boiling Point (°F)
−302.526°F
−244.147°F
Boiling Point (K)
87.3 K
119.93 K
Year Discovered:
1894
1898
CAS Number
7440-37-1
7439-90-9
Origin of Name:
The name is derived from the Greek, ''argos'', meaning idle.
The name is derived from the Greek ''kryptos'', meaning hidden.