HIV & AIDS

How HIV develops resistance to key drugs discovered

The mechanism behind how HIV can develop resistance to a widely-prescribed group of drugs has been uncovered by new research from the Crick and Dana-Farber Cancer Institute, with the findings opening the door to the development ...

Neuroscience

New tool devoted to simplifying complex neuron models

Scientists at the Hebrew University of Jerusalem and the EPFL Blue Brain Project have developed Neuron_Reduce, a new computational tool that provides the scientific community with a straightforward capability to simplify ...

Neuroscience

Study reveals mysteries of critical brain receptor complex

Glutamate receptors in the brain called AMPARs are critical for synaptic plasticity, learning and memory. Poorly functioning AMPARs have been linked to a wide range of neurological and psychiatric disorders including seizures, ...

Genetics

Gene that causes atrial fibrillation discovered

Genetic studies spanning three generations of a Persian Jewish family by researchers at Ben-Gurion University of the Negev (BGU) have identified a gene that causes nighttime atrial fibrillation (AFib).

Neuroscience

Why myelinated mammalian nerves are fast and allow high frequency

University of Alabama at Birmingham researchers, for the first time ever, have achieved patch-clamp studies of an elusive part of mammalian myelinated nerves called the Nodes of Ranvier. At the nodes, they found unexpected ...

Cardiology

Widely used blood pressure drugs might put heart at risk

Drugs based on a molecule called dihydropyridine are commonly prescribed by doctors to treat high blood pressure and angina, a chest pain caused by reduced blood flow to the heart. However, there's a chance that these same ...

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Ion

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