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Hydrogen (H)

Hydrogen is a chemical element of the periodic table with chemical symbol H and atomic number 1 with an atomic weight of 1.0079 u and is classed as nonmetal and is part of group 1 (alkali metal). Hydrogen is gas at room temperature.

Hydrogen in the periodic table

SymbolH
Atomic number1
Group1 (Alkali metal)
Period1
Blocks
ClassificationNonmetal
AppearanceColorless gas
Color Colorless
Number of protons1 p+
Number of neutrons0 n0
Number of electrons1 e-
From Wikipedia, the free encyclopediaHydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 1.00794 u, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.

Physical properties

Phase at STPGas
Density0.08988 g/cm3
Atomic weight1.0079 u

Thermal properties

Melting point13.99 K
-259.16 °C
-434.488 °F
Boiling point20.271 K
-252.879 °C
-423.1822 °F
Heat of vaporization0.4581 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)2.2
Electron affinity72.769 kJ/mol
Oxidation states−1, +1
(an amphoteric oxide)
Ionization energies
  1. 1312 kJ/mol

Electron configuration for hydrogen

Electron configuration
Shorthand configuration
1s1
Electron configuration
Full configuration
1s1
Electron configuration chart
1s1
Electrons per shell1
Valence electrons 1
Valency electrons 1
Bohr model
HydrogenElectron shell for Hydrogen, created by Injosoft ABH
Figure: Shell diagram of Hydrogen (H) atom.
Orbital Diagram
1s

The history of Hydrogen

Discovery and first isolationHenry Cavendish (1766)
Named byAntoine Lavoisier (1783)
Discovery of hydrogen
In 1671, Robert Boyle discovered and described the reaction between iron filings and dilute acids, which results in the production of hydrogen gas. In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by naming the gas from a metal-acid reaction "inflammable air". He speculated that "inflammable air" was in fact identical to the hypothetical substance called "phlogiston" and further finding in 1781 that the gas produces water when burned. He is usually given credit for the discovery of hydrogen as an element. In 1783, Antoine Lavoisier gave the element the name hydrogen (from the Greek ὑδρο- hydro meaning "water" and -γενής genes meaning "former") when he and Laplace reproduced Cavendish's finding that water is produced when hydrogen is burned.

Identifiers

List of unique identifiers for Hydrogen in various chemical registry databases
CAS Number1333-74-0
ChemSpider ID4515072
EC number215-605-7
PubChem CID Number783