Hydrogen vs Chlorine

Side-by-side comparison of Hydrogen (H, element 1) and Chlorine (Cl, element 17) by atomic structure and physical properties.

PropertyH Hydrogen Cl Chlorine
Atomic number117
SymbolHCl
NameHydrogenChlorine
Categorynonmetalhalogen
Standard Atomic Weight1.007975 u35.4515 u
Period13
Group117
Blocksp
Phase at STPGasGas
Electron configuration1s1[Ne]3s23p5
Oxidation states[-1, 1][-1, 1, 2, 3, 4, 5, 6, 7]
Electronegativity (Pauling)2.23.16
Electron affinity0.75419 eV3.6127 eV
Density0.08988 kg/m³3.214 kg/m³
Melting point-259.193 °C-101.5 °C
Boiling point-252.781 °C-34.04 °C
Discovery year17661774

Key Differences

PropertyH HydrogenCl Chlorine
Standard Atomic Weight1.007975 u ↓ lower35.4515 u ↑ higher
Density0.08988 kg/m³ ↓ lower3.214 kg/m³ ↑ higher
Melting point-259.193 °C ↓ lower-101.5 °C ↑ higher
Boiling point-252.781 °C ↓ lower-34.04 °C ↑ higher
Electronegativity (Pauling)2.2 ↓ lower3.16 ↑ higher
Electron affinity0.75419 eV ↓ lower3.6127 eV ↑ higher
Period1 3
Group1 17
Blocks p
Categorynonmetal halogen
Electron configuration1s1 [Ne]3s23p5
Discovery year1766 1774