Lithium fluoride crystals 'see' heavy ions with high energies

Lithium fluoride crystals have recently been used to register the tracks of nuclear particles. Physicists from the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow have just demonstrated that these ...

Ions clear another hurdle toward scaled-up quantum computing

Scientists at the Joint Quantum Institute (JQI) have been steadily improving the performance of ion trap systems, a leading platform for future quantum computers. Now, a team of researchers led by JQI Fellows Norbert Linke ...

Gene for acid-sensitive ion channel identified

In the human body the salt content of cells and their surrounding is regulated by sophisticated transport systems. Special channels in the cell membrane selectively permit salt ions to flow in and out of cells. A research ...

Ionic thermal up-diffusion boosts energy harvesting

Salinity gradient energy is recognized as a promising candidate for the substitution of traditional fossil fuels. Recently nanofluidic salinity gradient energy harvesting via ion channels or membranes has drawn increasing ...

Advance in understanding of all-solid-state batteries

All-solid-state batteries, a battery design composed of all solid components, have gained attention as the next major advance beyond lithium ion batteries because of their potential to store more energy while being safer ...

page 1 from 23


An ion is an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.

Since protons are positively charged and electrons are negatively charged, if there are more electrons than protons, the atom or molecule will be negatively charged. This is called an anion (pronounced /ˈænaɪən/; an-eye-on), from the Greek ἀνά (ana), meaning 'up'.

Conversely, if there are more protons than electrons, the atom or molecule will be positively charged. This is called a cation (pronounced /ˈkætaɪən/; cat-eye-on), from the Greek κατά (kata), meaning 'down'.

An ion consisting of a single atom is called a monatomic ion. If it consists of two or more atoms, it is called a polyatomic ion. Polyatomic ions containing oxygen, such as carbonate and sulfate, are called oxyanions.

When writing the chemical formula for an ion, its charge is written as a superscript '+' or '−' following a number indicating the difference between the number of protons and the number of electrons. The number is omitted if it is equal to 1. For example, the sodium cation is written as Na+, the '+' indicating that it has one less electron than it has protons. The sulfate anion is written as SO42−, the '2−' indicating that it has two more electrons than it has protons.

If an ion contains unpaired electrons, it is called a radical ion. Just like neutral radicals, radical ions are very reactive.

This text uses material from Wikipedia, licensed under CC BY-SA