An ion is an atom or molecule which has lost or gained one or more valence electrons, giving it a positive or negative electrical charge. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In chemistry valence electrons are the Electrons contained in the outermost or valence, Electron shell of an Atom.
A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion (pronounced /ˈænaɪən/; an-eye-on). The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron shell may be crudely thought of as an Orbit followed by Electrons around an Atom nucleus. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom Conversely, a positively-charged ion, which has fewer electrons than protons, is known as a cation (pronounced /ˈkætaɪən/; cat-eye-on).
An ion consisting of a single atom is called a monatomic ion, but if it consists of two or more atoms, it is a polyatomic ion. A monatomic ion is an Ion consisting of many ions of the same atoms A polyatomic ion is a charged species ( Ion) composed of two or more atoms covalently bonded or of a metal complex that can be considered as acting Polyatomic ions containing oxygen, such as carbonate and sulfate, are called oxyanions. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Chemistry, a carbonate is a salt or Ester of Carbonic acid. An oxyanion or oxoanion is a negatively charged Polyatomic ion that contains Oxygen.
Ions are denoted in the same way as electrically neutral atoms and molecules except for the presence of a superscript indicating the sign of the net electric charge and the number of electrons lost or gained, if more than one. For example: H+ and SO42−. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the
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Formation
Formation of polyatomic and molecular ions
Polyatomic and molecular ions are often formed by the combination of elemental ions such as H+ with neutral molecules or by the gain of such elemental ions from neutral molecules. A simple example of this is the ammonium ion NH4+ which can be formed by ammonia NH3 accepting a proton, H+. Ammonia and ammonium have the same number of electrons in essentially the same electronic configuration but differ in protons. The charge has been added by the addition of a proton (H+) not the addition or removal of electrons. The distinction between this and the removal of an electron from the whole molecule is important in large systems because it usually results in much more stable ions with complete electron shells. For example NH3·+ is not stable because of an incomplete valence shell around nitrogen and is in fact a radical ion. In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell
Ionization potential
The energy required to detach an electron in its lowest energy state from an atom or molecule of a gas with less net electric charge is called the ionization potential, or ionization energy. The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The nth ionization energy of an atom is the energy required to detach its nth electron after the first n − 1 electrons have already been detached.
Each successive ionization energy is markedly greater than the last. Particularly great increases occur after any given block of atomic orbitals is exhausted of electrons. An atomic orbital is a Mathematical function that describes the wave-like behavior of an electron in an atom For this reason, ions tend to form in ways that leave them with full orbital blocks. For example, sodium has one valence electron, in its outermost shell, so in ionized form it is commonly found with one lost electron, as Na+. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 In chemistry valence electrons are the Electrons contained in the outermost or valence, Electron shell of an Atom. On the other side of the periodic table, chlorine has seven valence electrons, so in ionized form it is commonly found with one gained electron, as Cl−. Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Francium has the lowest ionization energy of all the elements and fluorine has the greatest. Francium (ˈfrænsiəm formerly known as eka-caesium and actinium K, is a Chemical element that has the symbol Fr and Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 The ionization energy of metals is generally much lower than the ionization energy of nonmetals, which is why metals will generally lose electrons to form positively-charged ions while nonmetals will generally gain electrons to form negatively-charged ions. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Nonmetal is a term used in Chemistry when classifying the Chemical elements On the basis of their general physical and chemical properties every element in the
A neutral atom contains an equal number of Z protons in the nucleus and Z electrons in the electron shell. The electrons' negative charges thus exactly cancel the protons' positive charges. In the simple view of the Free electron model, a passing electron is therefore not attracted to a neutral atom and cannot bind to it. In Solid-state physics, the free electron model is a simple model for the behaviour of Valence electrons in a Crystal structure of a Metallic In reality, however, the atomic electrons form a cloud into which the additional electron penetrates, thus being exposed to a net positive charge part of the time. Furthermore, the additional charge displaces the original electrons and all of the Z + 1 electrons rearrange into a new configuration.
Ions
- Anions (see pronunciation above) are negatively charged ions, formed when an atom gains electrons in a reaction. Anions are negatively charged because there are more electrons associated with them than there are protons in their nuclei.
- Cations (see pronunciation above) are positively charged ions, formed when an atom loses electrons in a reaction. Cations are the opposite of anions, since cations have fewer electrons than protons.
- Dianion: a dianion is a species which has two negative charges on it; for example, the aromatic dianion pentalene. Pentalene is a polycyclic Hydrocarbon composed of two fused Cyclopentadiene rings
- Radical ions: radical ions are ions that contain an odd number of electrons and are mostly very reactive and unstable. In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell
Plasma
A collection of non-aqueous gas-like ions, or even a gas containing a proportion of charged particles, is called a plasma, often called the fourth state of matter because its properties are quite different from solids, liquids, and gases. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of This page is about the physical properties of gas as a state of matter Astrophysical plasmas containing predominantly a mixture of electrons and protons, may make up as much as 99. An astrophysical plasma is a plasma (an ionized gas found in astronomy whose physical properties are studied in the science of Astrophysics. 9% of visible matter in the universe. [1]
Applications
Ions are essential to life. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism Sodium, potassium, calcium and other ions play an important role in the cells of living organisms, particularly in cell membranes. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer They have many practical, everyday applications in items such as smoke detectors, and are also finding use in unconventional technologies such as ion engines. A smoke detector is a device that detects Smoke and issues an Alarm. An ion thruster is a form of Electric propulsion used for Spacecraft propulsion that creates thrust by accelerating Ions Ion thrusters are characterized Inorganic dissolved ions are a component of total dissolved solids, an indicator of water quality in the world. Total Dissolved Solids (often abbreviated TDS) is an expression for the combined content of all Inorganic and organic substances contained in a liquid Water quality is the physical chemical and biological characteristics of Water in relationship to a set of standards
Negative 'Ions' and Air Ionisers
Many manufacturers sell devices that release 'negative ions' into the air, claiming that a higher concentration of negative ions will make a room feel less 'stuffy'. Some also claim health benefits such as relieving asthma and depression. Asthma is a chronic Condition involving the Respiratory system in which the airways occasionally constrict become inflamed, and are Major depressive disorder, also known as major depression, unipolar depression, unipolar disorder, clinical depression, or simply depression
The 'ions' referred to are in fact charged oxygen or nitrogen molecules surrounded by a cluster of water molecules, rather than ions. Scientific studies have shown no particular benefit from a greater concentration of negative ions. [2]
Negative air ionization can reduce the concentration of bioaerosols and dust particles in the air by causing them to bond, forming larger particles and thus falling out of the air onto horizontal surfaces. This may help reduce infection due to airborne contamination[3]. Ionization was shown to reduce transmission of the Newcastle Disease Virus in an experiment with chickens[4].
Common ions
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References
- ^ Plasma, Plasma, Everywere Science@NASA Headline news, Space Science n° 158, September 7, 1999.
- ^ *Niels Jonassen (Mr. Static) "Are Ions Good for You?" Compliance Engineering, November 2002
- ^ Negative Air Ionization
- ^ Effect of Negative Air Ionization on Airborne Transmission of Newcastle Disease Virus. Bailey W. Mitchell, Daniel J. King. Avian Diseases, Vol. 38, No. 4 (Oct. - Dec. , 1994), pp. 725-732.
External links
- Department of Education, Newfoundland and Labrador-Canada "Periodic Chart of IonsPDF (70. 9 KiB)". A kibibyte (a contraction of ki lo bi nary byte) is a unit of Information or Computer storage, established by the International A Periodic table reporting ionic charges for every chemical element.
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