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Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, [ 11 ] but more commonly called hydrogen gas, molecular hydrogen or simply hydrogen. It is colorless, odorless, [ 12 ] non-toxic, and highly ...
The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows (" periods ") and columns (" groups "). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order ...
Hydrogen atom. 1 / 2 . Depiction of a hydrogen atom showing the diameter as about twice the Bohr model radius. (Image not to scale) A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a nucleus of a single positively charged proton and a single negatively charged electron bound to the ...
Instead, it forms diatomic H 2 molecules, similar to halogens and some nonmetals in the second period of the periodic table, such as nitrogen and oxygen. Diatomic hydrogen is a gas that, at atmospheric pressure, liquefies and solidifies only at very low temperature (20 K and 14 K respectively).
Hydrogen (1 H) has three naturally occurring isotopes: 1 H, 2 H, and 3 H. 1 H and 2 H are stable, while 3 H has a half-life of 12.32 (2) years. [ 3 ][ nb 1 ] Heavier isotopes also exist; all are synthetic and have a half-life of less than 1 zeptosecond (10 −21 s). [ 4 ][ 5 ] Of these, 5 H is the least stable, while 7 H is the most.
A hydrogen ion is created when a hydrogen atom loses an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space. [1] Due to its extremely high charge density of approximately 2×10 10 times that of a sodium ...
Dmitri Mendeleev, Russian chemist who proposed the periodic table: f-block groups 7 f-block [258] (10.3) (1100) – – 1.3 – synthetic unknown phase 102 No Nobelium: Alfred Nobel, Swedish chemist and engineer f-block groups 7 f-block [259] (9.9) (1100) – – 1.3 – synthetic unknown phase 103 Lr Lawrencium: Ernest Lawrence, American ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 25 August 2024. Development of the table of chemical elements The American chemist Glenn T. Seaborg —after whom the element seaborgium is named—standing in front of a periodic table, May 19, 1950 Part of a series on the Periodic table Periodic table forms 18-column 32-column Alternative and extended ...