Dictionary

hydrogen

The lightest (and, in our universe, the most abundant) chemical element. The atomic nucleus of an ordinary hydrogen atom is a single proton. If the atomic nucleus contains an additional neutron, the atom is called heavy hydrogen or deuterium.

Definitioner

hydrogen

deuterium

Variant of the chemical element hydrogen where the atomic nucleus consists not of a single proton, but of a proton and a neutron. In the context of general relativity it is of interest, as it is one of the species of light atomic nuclei, that formed in the early universe during Big Bang Nucleosynthesis.

atom

All matter we encounter in everyday life consists of smallest units called atoms - the air we breath consists of a wildly careening crowd of little groups of atoms, my computer's keyboard of a tangle of atom chains, the metal surface it rests on is a crystal lattice of atoms. All the variety of matter consists of less than hundred species of atoms (in other words: less than a hundred different chemical elements). Every atom consists of an nucleus surrounded by a cloud of electrons. Nearly all of the atom's mass is concentrated in its nucleus, while the structure of the electron cloud determines how the atom can bind to other atoms (in other words: its chemical properties). Every chemical element can be defined via a characteristic number of protons in its nucleus. Atoms that have lost some of their usual number of electrons are called ions. Atoms are extremely small (typical diametres are in the region of tenths of a billionth of a metre = 10^-10 metres), and to describe their properties and behaviour, one has to resort to quantum theory.

Dictionary

hydrogen

Further Articles

Tag Cloud