Surfing on waves in a one-dimensional quantum liquid

Physicists from the University of Luxembourg, together with international collaborators, have recently published an article in the internationally renowned journal Physical Review Letters. In this article, they demonstrate ...

Scientists develop a lithium-ion battery that won't catch fire

A flexible lithium-ion battery designed by a team of researchers from the Johns Hopkins Applied Physics Laboratory and built to operate under extreme conditions—including cutting, submersion, and simulated ballistic impact—can ...

Controlling ion recognition in reactive host-guest systems

Sometimes a molecule can only undergo a particular chemical reaction if it forms a so-called host-guest complex together with another molecule—the two molecules are then bound together not by covalent bonds but by intermolecular ...

Giving ATLAS a boost

The outer realms of the periodic table, where stable, long-lived isotopes give way to radioactive ions, offer nuclear scientists a unique glimpse into the structure of nuclei and a better understanding of how the different ...

Modelling ion beam therapy

Hadron beam therapy, which is often used to treat solid tumours, involves irradiating a tumour with a beam of high-energy charged particles, most often protons; these transfer their energy to the tumour cells, destroying ...

Peering into batteries: X-rays reveal lithium-ion's mysteries

Billions of smartphone owners are familiar with the dreaded "low battery" symbol on their devices. While consumers groan, scientists are working to understand why and when lithium-ion batteries in phones, plug-in electric ...

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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