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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 H 2, sometimes called dihydrogen, [11] hydrogen gas, molecular hydrogen, or simply hydrogen. It is colorless, odorless, [12] non-toxic, and highly combustible.
In the periodic table of the elements, each column is a group. In chemistry, a group (also known as a family) [1] is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the 14 f-block columns, between groups 2 and 3, are not numbered.
Elements of the group have one s-electron in the outer electron shell. Hydrogen is not considered to be an alkali metal as it is not a metal, though it is more analogous to them than any other group. This makes the group somewhat exceptional. b The 14 f-block groups (columns) do not have a group number.
Hydrogen is the element with atomic number 1; ... Elements with similar chemical properties generally fall into the same group in the periodic table, although in the ...
A period on the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, elements in the same group (column) have similar chemical and physical properties, reflecting the periodic law.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Usually, hydrogen is placed in group 1, and helium in group 18: this is the placement found on the IUPAC periodic table. [3] Some variation can be found on both these matters. [4] Like the group 1 metals, hydrogen has one electron in its outermost shell [2] and typically loses its only electron in chemical reactions. [5]
The pnictogens [1] (/ ˈ p n ɪ k t ə dʒ ə n / or / ˈ n ɪ k t ə dʒ ə n /; from Ancient Greek: πνῑ́γω "to choke" and -gen, "generator") are the chemical elements in group 15 of the periodic table. This group is also known as the nitrogen group or nitrogen family.