- published: 24 Oct 2015
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An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass ("go") between electrodes in a solution, when an electric field is applied. It is the transliteration of the Greek participle ἰόν, ión, "going".
An ion consisting of a single atom is an atomic or monatomic ion; if it consists of two or more atoms, it is a molecular or polyatomic ion.
An anion (−) ( /ˈæn.aɪ.ən/ AN-eye-ən), from the Greek word ἄνω (ánō), meaning "up", is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged).
A cation (+) ( /ˈkæt.aɪ.ən/ KAT-eye-ən), from the Greek word κατά (katá), meaning "down", is an ion with fewer electrons than protons, giving it a positive charge. Since the charge on a proton is equal in magnitude to the charge on an electron, the net charge on an ion is equal to the number of protons in the ion minus the number of electrons.
The lake lay blue below the hill
The lake lay blue below the hill, below the hill
As I looked, there flew across the waters cold and still
A bird whose wings were palest blue
The sky above was blue at last
The sky beneath me blue in blue, was blue in blue
A moment ere the bird had passed
It called, as if in a trance he flew