Hydrogen (H) VS Helium (He)
A definitive side-by-side comparison of two essential element profiles.
VS
Main Differences
Hydrogen (H) is an element in the nonmetals category with an atomic number of 1. Helium (He) is an element in the noble gases category with an atomic number of 2.
Helium (He) is 2.0x denser than Hydrogen (H). Furthermore, Hydrogen (H) melts at a significantly higher temperature than Helium (He) (a difference of 12.9 Kelvin).
Where do the names come from?
Hydrogen (H) Naming History
The name Hydrogen is derived from the Greek 'hydro' and 'genes' meaning water forming.
He Helium (He) Naming History
The name is derived from the Greek, 'helios' meaning sun, as it was in the sun's corona that helium was first detected.
Related Comparisons
Compare
Hydrogen (H)
Helium (He)
Category
Nonmetals
Noble Gases
Atomic Number
1
2
Symbol
H
He
Atomic Mass
1.008 u
4.003 u
Group
1
18
Period
1
1
Block
s-block
s-block
Standard State (at 20°C)
gas
gas
Density
0.089 g/L g/cm³
0.178 g/L g/cm³
Melting Point (°C)
−259.16°C
N/A
Melting Point (°F)
−434.49°F
N/A
Melting Point (K)
13.83 K
0.95 K
Boiling Point (°C)
−252.879°C
−268.928°C
Boiling Point (°F)
−423.182°F
−452.07°F
Boiling Point (K)
20.27 K
4.22 K
Year Discovered:
1766
1895
CAS Number
133-74-0
7440-59-7
Origin of Name:
The name is derived from the Greek 'hydro' and 'genes' meaning water forming.
The name is derived from the Greek, 'helios' meaning sun, as it was in the sun's corona that helium was first detected.