If there are more electrons than protons, the species has a negative charge. The number of neutrons determines the isotope of an element but does not affect the electrical charge. Cations are ions with a net positive charge. Anions are ions with a net negative charge. Because they have opposite electrical charges , cations and anions are attracted to each other. Cations repel other cations and anions repel other anions. Sometimes, you can predict whether an atom will form a cation or an anion based on its position on the periodic table.
Alkali metals and alkaline earth metals always form cations. Halogens always form anions. Most other nonmetals typically form anions e. When writing the formula of a compound, the cation is listed before the anion. For example, in NaCl, the sodium atom acts as the cation, while the chlorine atom acts as the anion. Citations Cited By. This article is cited by 42 publications.
Zhi Sun, Kevin B. Moore, III, J. Grant Hill, Kirk A. Peterson, Henry F. The Journal of Physical Chemistry B , 13 , Gutsev , K. Belay , C. Weatherford , B.
Ramachandran , L. Gutsev , and P. The Journal of Physical Chemistry A , 24 , On The Nature of the Halogen Bond. Journal of Chemical Theory and Computation , 10 9 , Inorganic Chemistry , 52 20 , The Journal of Physical Chemistry Letters , 3 20 , Inorganic Chemistry , 50 22 , The Journal of Physical Chemistry A , 33 , The Journal of Physical Chemistry A , 50 , Angewandte Chemie , 5 , Angewandte Chemie International Edition , 60 5 , One example is in the process of electrolysis , which involves an electric current passing through a material and producing a chemical reaction.
During electrolysis, the positively charged cations are attracted to a negatively-charged electrode called a cathode. Anions are attracted to a positively-charged electrode called an anode. The first records of the words cation and anion in English come from around the s. Remember: the number of electrons in a cation has gone down, resulting in a positive charge.
The number of electrons in an anion has gone up, resulting in a negative charge. Many elements can take the form of either anions or cations depending on the situation. Oxygen often exists in a neutral state, but oxygen atoms tend to form anions by gaining two electrons.
Atoms of other elements also tend to form anions , including nitrogen , chlorine , and fluorine , among others. By contrast, atoms of calcium , magnesium , aluminum , and sodium tend to lose electrons and form cations. Remember, cations are positive ions—they are positively charged because they have lost one or more electrons and therefore have more protons than electrons.
Anions are negative ions—they are negatively charged because they have gained one or more electrons and therefore have more electrons than protons. It is important not to misinterpret the concept of being isoelectronic. A sodium ion is very different from a neon atom because the nuclei of the two contain different numbers of protons.
One is an essential ion that is a part of table salt, while the other is an unreactive gas that is a very small part of the atmosphere. Neon gas A and sodium chloride crystals B.
Neon atoms and sodium ions are isoelectronic. Neon is a colorless and unreactive gas that glows a distinctive red-orange color in a gas discharge tube. Sodium ions are most commonly found in crystals of sodium chloride, ordinary table salt.
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