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helium vs hydrogen

Input interpretation

helium (chemical element) | hydrogen (chemical element)
helium (chemical element) | hydrogen (chemical element)

Periodic table location

Periodic table location
Periodic table location

Images

Images
Images

Basic elemental properties

| helium | hydrogen atomic symbol | He | H atomic number | 2 | 1 short electronic configuration | 1s^2 | 1s^1 Aufbau diagram | 1s | 1s block | s | s group | 18 | 1 period | 1 | 1 atomic mass | 4.002602 u | 1.008 u half-life | (stable) | (stable)
| helium | hydrogen atomic symbol | He | H atomic number | 2 | 1 short electronic configuration | 1s^2 | 1s^1 Aufbau diagram | 1s | 1s block | s | s group | 18 | 1 period | 1 | 1 atomic mass | 4.002602 u | 1.008 u half-life | (stable) | (stable)

Thermodynamic properties

| helium | hydrogen phase at STP | gas | gas melting point | | -259.14 °C boiling point | -268.93 °C | -252.87 °C critical temperature | 5.19 K | 32.97 K critical pressure | 0.227 MPa | 1.293 MPa molar heat of fusion | 0.02 kJ/mol | 0.558 kJ/mol molar heat of vaporization | 0.083 kJ/mol | 0.452 kJ/mol specific heat at STP | 5193.1 J/(kg K) | 14300 J/(kg K) adiabatic index | 5/3 | 7/5 (properties at standard conditions)
| helium | hydrogen phase at STP | gas | gas melting point | | -259.14 °C boiling point | -268.93 °C | -252.87 °C critical temperature | 5.19 K | 32.97 K critical pressure | 0.227 MPa | 1.293 MPa molar heat of fusion | 0.02 kJ/mol | 0.558 kJ/mol molar heat of vaporization | 0.083 kJ/mol | 0.452 kJ/mol specific heat at STP | 5193.1 J/(kg K) | 14300 J/(kg K) adiabatic index | 5/3 | 7/5 (properties at standard conditions)

Material properties

| helium | hydrogen density | 1.785×10^-4 g/cm^3 | 8.99×10^-5 g/cm^3 molar volume | 22420 cm^3/mol | 11200 cm^3/mol refractive index | 1.000035 | 1.000132 sound speed | 970 m/s | 1270 m/s thermal conductivity | 0.1513 W/(m K) | 0.1805 W/(m K) (properties at standard conditions)
| helium | hydrogen density | 1.785×10^-4 g/cm^3 | 8.99×10^-5 g/cm^3 molar volume | 22420 cm^3/mol | 11200 cm^3/mol refractive index | 1.000035 | 1.000132 sound speed | 970 m/s | 1270 m/s thermal conductivity | 0.1513 W/(m K) | 0.1805 W/(m K) (properties at standard conditions)

Electromagnetic properties

| helium | hydrogen magnetic type | diamagnetic | diamagnetic volume magnetic susceptibility | -1.05×10^-9 | -2.23×10^-9 mass magnetic susceptibility | -5.9×10^-9 m^3/kg (cubic meters per kilogram) | -2.48×10^-8 m^3/kg (cubic meters per kilogram) molar magnetic susceptibility | -2.36×10^-11 m^3/mol (cubic meters per mole) | -4.999×10^-11 m^3/mol (cubic meters per mole) color | (colorless) | (colorless) refractive index | 1.000035 | 1.000132
| helium | hydrogen magnetic type | diamagnetic | diamagnetic volume magnetic susceptibility | -1.05×10^-9 | -2.23×10^-9 mass magnetic susceptibility | -5.9×10^-9 m^3/kg (cubic meters per kilogram) | -2.48×10^-8 m^3/kg (cubic meters per kilogram) molar magnetic susceptibility | -2.36×10^-11 m^3/mol (cubic meters per mole) | -4.999×10^-11 m^3/mol (cubic meters per mole) color | (colorless) | (colorless) refractive index | 1.000035 | 1.000132

Reactivity

| helium | hydrogen valence | 0 | 1 electronegativity | | 2.2 electron affinity | 0 kJ/mol (kilojoules per mole) | 72.8 kJ/mol (kilojoules per mole) first ionization energy | 2372.3 kJ/mol (kilojoules per mole) | 1312 kJ/mol (kilojoules per mole) ionization energies | 2372.3 kJ/mol | 5250.5 kJ/mol | 1312 kJ/mol
| helium | hydrogen valence | 0 | 1 electronegativity | | 2.2 electron affinity | 0 kJ/mol (kilojoules per mole) | 72.8 kJ/mol (kilojoules per mole) first ionization energy | 2372.3 kJ/mol (kilojoules per mole) | 1312 kJ/mol (kilojoules per mole) ionization energies | 2372.3 kJ/mol | 5250.5 kJ/mol | 1312 kJ/mol
Reactivity
Reactivity

Atomic properties

| helium | hydrogen term symbol | ^1S_0 | ^2S_(1/2) atomic radius | 31 pm | 25 pm covalent radius | 28 pm | 31 pm van der Waals radius | 140 pm | 120 pm (electronic ground state properties)
| helium | hydrogen term symbol | ^1S_0 | ^2S_(1/2) atomic radius | 31 pm | 25 pm covalent radius | 28 pm | 31 pm van der Waals radius | 140 pm | 120 pm (electronic ground state properties)

Abundances

| helium | hydrogen universe abundance | 23 mass% | 75 mass% solar abundance | 23 mass% | 75 mass% meteorite abundance | | 2.4 mass% crust abundance | 5.5×10^-7 mass% | 0.15 mass% ocean abundance | 7.2×10^-10 mass% | 11 mass% human abundance | | 10 mass% universe molar abundance | 7.2 mol% | 93 mol% solar molar abundance | 7.4 mol% | 93 mol% meteorite molar abundance | | 17 mol% ocean molar abundance | 1.1×10^-9 mol% | 66 mol% crust molar abundance | 3×10^-6 mol% | 3.1 mol% human molar abundance | | 62 mol%
| helium | hydrogen universe abundance | 23 mass% | 75 mass% solar abundance | 23 mass% | 75 mass% meteorite abundance | | 2.4 mass% crust abundance | 5.5×10^-7 mass% | 0.15 mass% ocean abundance | 7.2×10^-10 mass% | 11 mass% human abundance | | 10 mass% universe molar abundance | 7.2 mol% | 93 mol% solar molar abundance | 7.4 mol% | 93 mol% meteorite molar abundance | | 17 mol% ocean molar abundance | 1.1×10^-9 mol% | 66 mol% crust molar abundance | 3×10^-6 mol% | 3.1 mol% human molar abundance | | 62 mol%

Nuclear properties

| helium | hydrogen half-life | (stable) | (stable) stable isotopes | He-4 (99.999863%) | He-3 (1.37×10^-6) | H-1 (99.985%) | H-2 (1.5×10^-4) nuclear spin | He-3: 1/2^+ | He-4: 0^+ | He-5: 3/2^- | He-6: 0^+ | He-7: 3/2^- | He-8: 0^+ | He-9: 1/2^+ | He-10: 0^+ | H-1: 1/2^+ | H-2: 1^+ | H-3: 1/2^+ | H-4: 2^- | H-5: 1/2^+ | H-6: 2^- | H-7: 1/2^+ unstable isotopes | He-6 (806.7 ms) | He-8 (119 ms) | He-9 (7 zs) | He-7 (3.04 zs) | He-10 (1.52 zs) | He-5 (0.76 zs) | H-3 (12.32 yr) | H-6 (0.29 zs) | H-4 (0.139 zs) | H-5 (0.08 zs) | H-7 (0.023 zs) neutron cross-section | 0.007 b | 0.332 b neutron mass absorption | 1×10^-5 m^2/kg | 0.011 m^2/kg
| helium | hydrogen half-life | (stable) | (stable) stable isotopes | He-4 (99.999863%) | He-3 (1.37×10^-6) | H-1 (99.985%) | H-2 (1.5×10^-4) nuclear spin | He-3: 1/2^+ | He-4: 0^+ | He-5: 3/2^- | He-6: 0^+ | He-7: 3/2^- | He-8: 0^+ | He-9: 1/2^+ | He-10: 0^+ | H-1: 1/2^+ | H-2: 1^+ | H-3: 1/2^+ | H-4: 2^- | H-5: 1/2^+ | H-6: 2^- | H-7: 1/2^+ unstable isotopes | He-6 (806.7 ms) | He-8 (119 ms) | He-9 (7 zs) | He-7 (3.04 zs) | He-10 (1.52 zs) | He-5 (0.76 zs) | H-3 (12.32 yr) | H-6 (0.29 zs) | H-4 (0.139 zs) | H-5 (0.08 zs) | H-7 (0.023 zs) neutron cross-section | 0.007 b | 0.332 b neutron mass absorption | 1×10^-5 m^2/kg | 0.011 m^2/kg

Identifiers

| helium | hydrogen CAS number | 7440-59-7 | 1333-74-0 PubChem CID number | 23987 | 783
| helium | hydrogen CAS number | 7440-59-7 | 1333-74-0 PubChem CID number | 23987 | 783

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