Hydrogen Element Information, Facts, Properties, Trends, Uses, Comparison with other elements
Hydrogen 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.
It belongs to group 1 of the periodic table having trivial name alkali metals*. You can also download Printable Periodic Table of Elements Flashcards for Hydrogen in a PDF format.
Hydrogen Facts
Read key information and facts about element Hydrogen
| Name | Hydrogen |
| Atomic Number | 1 |
| Atomic Symbol | H |
| Atomic Weight | 1.00794 |
| Phase | Gas(Diatomic Gas) |
| Color | Colorless |
| Appearance | colorless gas |
| Classification | Other Nonmetal |
| Natural Occurance | Primordial |
| Group in Periodic Table | 1 |
| Group Name | lithium family |
| Period in Periodic Table | period 1 |
| Block in Periodic Table | s-block |
| Electronic Configuration | 1s1 |
| Electronic Shell Structure (Electrons per shell) | 1 |
| Melting Point | 14.01 K |
| Boiling Point | 20.28 K |
| CAS Number | CAS1333-74-0 |
How to Locate Hydrogen on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 1 to find Hydrogen on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Hydrogen on periodic table look for cross section of group 1 and period 1 in the modern periodic table.
Hydrogen History
The element Hydrogen was discovered by H. Cavendish in year 1766 in United Kingdom. Hydrogen was first isolated by Paracelsus in 1500. Hydrogen derived its name from the Greek elements hydro- and -gen meaning 'water-forming'.
| Discovered By | H. Cavendish |
| Discovery Date | 1766 in United Kingdom |
| First Isolation | 1500 |
| Isolated by | Paracelsus |
Cavendish was the first to distinguish from other gases, although Paracelsus around 1500, Robert Boyle, and Joseph Priestley had observed its production by reacting strong acids with metals. Lavoisier named it in 1793.
Hydrogen Uses
Hydrogen constitutes about 90 percent of the universe's atoms. The chemical is used majorly as both a gas and liquid fuel. Hydrogen was used as a main fuel for the Space Shuttle program by NASA and is currently being used heavily by the petroleum and manufacturing industries.
Hydrogen Presence: Abundance in Nature and Around Us
The table below shows the abundance of Hydrogen in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
| ppb by weight (1ppb =10^-7 %) | ppb by atoms (1ppb =10^-7 %) | |
|---|---|---|
| Abundance in Universe | 750000000 | 930000000 |
| Abundance in Sun | 750000000 | 930000000 |
| Abundance in Meteorites | 24000000 | 170000000 |
| Abundance in Earth's Crust | 1500000 | 31000000 |
| Abundance in Oceans | 107800000 | 662000000 |
| Abundance in Humans | 100000000 | 620000000 |
Crystal Structure of Hydrogen
The solid state structure of Hydrogen is Simple Hexagonal.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
Unit Cell Parameters
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)
| a | b | c |
|---|---|---|
| 470 pm | 470 pm | 340 pm |
and the angles between them Lattice Angles (alpha, beta and gamma).
| alpha | beta | gamma |
|---|---|---|
| π/2 | π/2 | 2 π/3 |
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.
| Space Group Name | P63/mmc |
| Space Group Number | 194 |
| Crystal Structure | Simple Hexagonal |
| Number of atoms per unit cell |
The number of atoms per unit cell in a simple cubic, face-centered cubic and body-centred cubic are 1,4,2 respectively.
Hydrogen Atomic and Orbital Properties
Hydrogen atoms have 1 electrons and the electronic shell structure is [1] with Atomic Term Symbol (Quantum Numbers) 2S1/2.
| Atomic Number | 1 |
| Number of Electrons (with no charge) | 1 |
| Number of Protons | 1 |
| Mass Number | 1 |
| Number of Neutrons | 0 |
| Shell structure (Electrons per energy level) | 1 |
| Electron Configuration | 1s1 |
| Valence Electrons | 1s1 |
| Valence (Valency) | 1 |
| Main Oxidation States | -1, 1 |
| Oxidation States | -1, 1 |
| Atomic Term Symbol (Quantum Numbers) | 2S1/2 |
Bohr Atomic Model of Hydrogen - Electrons per energy level
| n | s | p | d | f |
|---|
Ground State Electronic Configuration of Hydrogen - neutral Hydrogen atom
Abbreviated electronic configuration of Hydrogen
The ground state abbreviated electronic configuration of Neutral Hydrogen atom is 1s1. The portion of Hydrogen configuration that is equivalent to the noble gas of the preceding period, is abbreviated as . For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 1s1, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Hydrogen
Complete ground state electronic configuration for the Hydrogen atom, Unabbreviated electronic configuration
1s1
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.
As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.
Hund's rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.
Atomic Structure of Hydrogen
Hydrogen atomic radius is 53 pm, while it's covalent radius is 37 pm.
| Atomic Radius Calculated | 53 pm(0.53 Å) |
| Atomic Radius Empirical | 25 pm (0.25 Å) |
| Atomic Volume | 22.4135 cm3/mol |
| Covalent Radius | 37 pm (0.37 Å) |
| Van der Waals Radius | 120 pm |
| Neutron Cross Section | 0.332 |
| Neutron Mass Absorption | 0.011 |
Spectral Lines of Hydrogen - Atomic Spectrum of Hydrogen
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.
Spectral lines are the result of interaction between a quantum system and a single photon. A spectral line may be observed either as an emission line or an absorption line.
Spectral lines are highly atom-specific, and can be used to identify the chemical composition of any medium. Several elements, including helium, thallium, and caesium, were discovered by spectroscopic means. They are widely used to determine the physical conditions of stars and other celestial bodies that cannot be analyzed by other means.
Emission spectrum of Hydrogen
Absorption spectrum of Hydrogen
Hydrogen Chemical Properties: Hydrogen Ionization Energies and electron affinity
The electron affinity of Hydrogen is 72.8 kJ/mol.
| Valence | 1 |
| Electronegativity | 2.2 |
| ElectronAffinity | 72.8 kJ/mol |
Ionization Energy of Hydrogen
Ionization energy is the amount of energy required to remove an electron from an atom or molecule.in chemistry, this energy is expresed in kilocalories per mole (kcal/mol) or kilojoules per mole (kJ/mol).
Refer to table below for Ionization energies of Hydrogen
| Ionization energy number | Enthalpy - kJ/mol |
|---|---|
| 1st | 1312 |
Hydrogen Physical Properties
Refer to below table for Hydrogen Physical Properties
| Density | 0.0000899 g/cm3 |
| Molar Volume | 22.4135 cm3/mol |
Elastic Properties
| Young Modulus | - |
| Shear Modulus | - |
| Bulk Modulus | - |
| Poisson Ratio | - |
Hardness of Hydrogen - Tests to Measure of Hardness of Element
| Mohs Hardness | - |
| Vickers Hardness | - |
| Brinell Hardness | - |
Hydrogen Electrical Properties
Electrical resistivity measures element's electrical resistance or how strongly it resists electric current.The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). While Electrical conductivity is the reciprocal of electrical resistivity. It represents a element's ability to conduct electric current. The SI unit of electrical conductivity is siemens per metre (S/m).
Hydrogen is a -. Refer to table below for the Electrical properties of Hydrogen
| Electrical conductors | - |
| Electrical Conductivity | - |
| Resistivity | - |
| Superconducting Point | - |
Hydrogen Heat and Conduction Properties
| Thermal Conductivity | 0.1805 W/(m K) |
| Thermal Expansion | - |
Hydrogen Magnetic Properties
| Magnetic Type | Diamagnetic |
| Curie Point | - |
| Mass Magnetic Susceptibility | -2.48e-8 m3/kg |
| Molar Magnetic Susceptibility | -4.999e-11 m3/mol |
| Volume Magnetic Susceptibility | -2.23e-9 |
Optical Properties of Hydrogen
| Refractive Index | 1.000132 |
Acoustic Properties of Hydrogen
| Speed of Sound | 1270 m/s |
Hydrogen Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Hydrogen
| Melting Point | 14.01 K(-259.14 °C, -434.452 °F) |
| Boiling Point | 20.28 K(-252.87 °C, -423.166 °F) |
| Critical Temperature | 32.97 K |
| Superconducting Point | - |
Enthalpies of Hydrogen
| Heat of Fusion | 0.558 kJ/mol |
| Heat of Vaporization | 0.452 kJ/mol |
| Heat of Combustion | - |
Hydrogen Isotopes - Nuclear Properties of Hydrogen
Hydrogen has 7 isotopes, with between 1 and 7 nucleons. Hydrogen has 2 stable naturally occuring isotopes.
Isotopes of Hydrogen - Naturally occurring stable Isotopes: 1H, 2H.
| Isotope | Z | N | Isotope Mass | % Abundance | T half | Decay Mode |
|---|---|---|---|---|---|---|
| 1H | 1 | 0 | 1 | 99.9885% | Stable | |
| 2H | 1 | 1 | 2 | 0.0115% | Stable | N/A |
| 3H | 1 | 2 | 3 | Synthetic | ||
| 4H | 1 | 3 | 4 | Synthetic | ||
| 5H | 1 | 4 | 5 | Synthetic | ||
| 6H | 1 | 5 | 6 | Synthetic | ||
| 7H | 1 | 6 | 7 | Synthetic |
Regulatory and Health - Health and Safety Parameters and Guidelines
The United States Department of Transportation (DOT) identifies hazard class of all dangerous elements/goods/commodities either by its class (or division) number or name. The DOT has divided these materials into nine different categories, known as Hazard Classes.
| DOT Numbers | 1966 |
| DOT Hazard Class | 2.1 |
NFPA 704 is a Standard System for the Identification of the Hazards of Materials for Emergency Response. NFPA is a standard maintained by the US based National Fire Protection Association.
The health (blue), flammability (red), and reactivity (yellow) rating all use a numbering scale ranging from 0 to 4. A value of zero means that the element poses no hazard; a rating of four indicates extreme danger.
| NFPA Fire Rating | 4 | Flash Points below 22.8°C (73°F) |
| NFPA Health Rating | 3 | Flash Points below 37.8°C (100°F) |
| NFPA Reactivity Rating | 0 | Will not burn |
| NFPA Hazards |
| Autoignition Point | 535.5 °C |
| Flashpoint | -18 °C |
Database Search
List of unique identifiers to search the element in various chemical registry databases
| Database | Identifier number |
|---|---|
| CAS Number - Chemical Abstracts Service (CAS) | CAS1333-74-0 |
| RTECS Number | RTECSMW8900000 |
| CID Number | CID783 |
| Gmelin Number | - |
| NSC Number | - |
Compare Hydrogen with other elements
Compare Hydrogen with Group 1, Period 1 and Other Nonmetal elements of the periodic table.
Compare Hydrogen with all Group 1 elements
Compare Hydrogen with all Period 1 elements
Compare Hydrogen with all Other Nonmetal elements
Frequently Asked Questions (FAQ)
Find the answers to the most frequently asked questions about Hydrogen