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Topic: Electron affinity


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  Chemical Bond Data
Electron affinity: the energy change when a neutral atom attracts an electron to become a negative ion.
The electron affinity is a measure of the energy change when an electron is added to a neutral atom to form a negative ion.
It is said to have an electron affinity of -349 kJ/mol and this large number indicates that it forms a stable negative ion.
hyperphysics.phy-astr.gsu.edu /hbase/chemical/bondd.html   (569 words)

  
 Electron device employing a low/negative electron affinity electron source - Patent 5283501
An electron device with an electron source comprising a single crystal diamond material which exhibits an inherent affinity to retain electrons disposed at/near a surface of the single crystal diamond material which is less than approximately 1.0 electron volt, the surface being substantially a preferred crystallographic orientation or plane of the single crystal diamond material.
The electron device of claim 24 wherein the signal means is further coupled to the electron source such that electron emission from the electron source is controlled by preferentially selecting a voltage level of the signal means and wherein emitted electrons are collected at the anode.
Electron source 410 includes a diamond semiconductor material having a surface corresponding to the 111 crystallographic plane and wherein any electrons 412 spontaneously emitted from the surface of the diamond material reside in a charge cloud immediately adjacent to the semiconductor surface.
www.freepatentsonline.com /5283501.html   (5858 words)

  
 Electron affinity - Wikipedia, the free encyclopedia
Electron Affinity is the amount of energy given off when a neutral atom gains electrons to form a negative ion.
Electron affinities are not limited to the elements but also apply to molecules.
For instance the electron affinity for benzene is positive, that of naphthalene near zero and that of anthracene positive.
en.wikipedia.org /wiki/Electron_affinity   (214 words)

  
 Chemistry : Chapter 6 : Overview   (Site not responding. Last check: 2007-11-03)
Electron affinity is the energy required to add an electron to a gaseous atom.
The electrons involved in bonding are the outermost, or valence electrons.
Assigned electrons are all electrons in lone pairs associated with the atom and half of all electrons in the bonds associated with the atom.
www.wwnorton.com /chemistry/overview/ch6.htm   (1457 words)

  
 Ionization Energies and Electron Affinities   (Site not responding. Last check: 2007-11-03)
Electron affinity is a measure of the energy released (or absrobed) when an atom accepts an additional electron.
Notice that the electron affinity of these Group 1 elements decreases gently as we go from H to K reflecting the fact that the larger atom has a weaker Coulombic attraction for the extra electron.
While the electron affinity for the first of these electrons is strongly negative, the affinity for the second is actually positive because of the additional repulsion associated with bringing an electron into a negatively charged species.
neon.chem.uidaho.edu /~honors/ionpot.html   (982 words)

  
 Electronic Properties
This is the electron affinity in the case of a non-metal.
Electrons are bound to atoms and corrections are added for overlap of the electron density produced by different atoms.
The finite wavelength of the electrons causes Friedel oscillations in the electron density near the surface (this is analogous to what happens when one tries to express a step function as a sum of sinusoidal functions up to a maximum frequency).
www.virginia.edu /ep/SurfaceScience/electron.html   (2062 words)

  
 Periodic Table
As you move down the group the electrons are in higher energy levels and are less affected by the pull of the nucleus.
As you move down a group the electron affinity decreases because of the shielding effect and the atomic radius.
The electronegativity of an atom is the tendency of the atom to attract electrons to itself during a chemical reaction.
home1.gte.net /vze4gq6z/id8.html   (827 words)

  
 Periodicity of Atomic Properties
The reason for this decrease is that with in a period, the outer electrons are in the same energy level, yet they are subjected to an increasing force of attraction from an increasingly positively charged nucleus, which causes a "shrinking" in the average distance of the outer electrons.
The reason for this is that the additional electron increases the mutual repulsion between the electrons, and this causes an expansion of the electron orbitals.
The electron affinity of chlorine is 349 kJ.mol
www.physchem.co.za /Atomic/Periodicity.htm   (1122 words)

  
 Dictionary E (Part 2 of 2)   (Site not responding. Last check: 2007-11-03)
The electron microscope is a form of microscope that uses a beam of electrons instead of a beam of light (as in optical microscope) to form a large image of a very small object.
Electron pair repulsion is the divergent force between the electron pairs in the sub-orbitals of the valence shell about an atom.
Electron pairs are the two electrons which have opposite spins that occupy the same sub-orbital in the valence shell of an atom, or in the single covalent bond between atoms.
www.ucc.ie /ucc/depts/chem/dolchem/html/dict/000e2.html   (3100 words)

  
 Ionization Energy and Electron Affinity
Furthermore, the electron being removed when the first ionization energy is measured spends less of its time near the nucleus of the atom, and it therefore takes less energy to remove this electron from the atom.
Electron affinities are more difficult to measure than ionization energies and are usually known to fewer significant figures.
Electron affinity data are complicated by the fact that the repulsion between the electron being added to the atom and the electrons already present on the atom depends on the volume of the atom.
chemed.chem.purdue.edu /genchem/topicreview/bp/ch7/ie_ea.html   (2001 words)

  
 Re: Electron affinity   (Site not responding. Last check: 2007-11-03)
Electron affinity of an element is the energy given off when a gaseous atom gains an electron to from a negatively charged ion.
Electron affinity of the fluorine is +328kj/mol because the amount of energy given off.
2)The electron affinities of the noble gase are slightly negative.
vclass.mtsac.edu:920 /chem1a/_disc8/0000004d.htm   (165 words)

  
 Photoelectric converter with electron injection preventive layer - Patent 5311038
An electron injection preventive layer is inserted between the semiconductor layer and the second electrode for preventing electrons from being injected from the second electrode into the semiconductor layer.
The electron injection preventive layer is formed of a material satisfying the inequality:.phi..sub.M -x.sub.2.gtoreq.Eg.sub.1 where the work function of the second electrode is.phi..sub.M, the electron affinity of the electron injection preventive layer is x.sub.2, and the band gap energy of the semiconductor layer is Eg.sub.1.
An electron injection preventive layer for preventing electrons from being injected from the second electrode to the semiconductor is inserted between the semiconductor and the second electrode.
www.freepatentsonline.com /5311038.html   (3974 words)

  
 Chapter 2-b sci 210 by J Gniadek Unit 1: Section 2   (Site not responding. Last check: 2007-11-03)
The energy required to remove a second electron from the outer level of an atom (the second ionization energy) is always greater than that required to remove the outermost electron.
6-4 shows that the radius of maximum probability for the 2s electron is, on the average, slightly farther from the nucleus than the 2p electron, but the small hump in the curve for the 2s electron close to the nucleus represents a greater electron density closer to the nucleus.
Electronegativity is a measure of the tendency of an atom in a molecule or aggregate of atoms to attract electrons.
www.chemistry210.com /notes/u01s06f.htm   (2747 words)

  
 CU Boulder :: Ellison :: photoelectron spectroscopy
The electron affinity (EA) of a molecule is the binding energy of the electron to the neutral molecule.
1 indicates that, the electron affinity of R is the transition energy from the ground vibrational/rotational state of the anion to the ground vibrational/rotational state of the neutral: EA(R) R, v’=0, J’=0>←R, v"=0, J"=0>; the electron affinity associated with the (0,0) band in Fig.
In (4), m and e are the electron mass and charge, whereas υ is the asymptotic electron velocity and ν is the photon frequency.
www.colorado.edu /chem/ellison/research/resPhotoelectronSpectro.html   (2533 words)

  
 electron affinity
Electron affinities are the negative ion equivalent, and their use is almost always confined to elements in groups 6 and 7 of the Periodic Table.
The first electron affinity is the energy released when 1 mole of gaseous atoms each acquire an electron to form 1 mole of gaseous 1- ions.
The second electron affinity is the energy required to add an electron to each ion in 1 mole of gaseous 1- ions to produce 1 mole of gaseous 2- ions.
www.chemguide.co.uk /atoms/properties/eas.html   (1106 words)

  
 Ionization Energy and Electron Affinity
When an electron is in the next subshell, Ionization Energy will lower because the outer electron is at a greater distance from the nucleus and there is more shielding from inner subshells.
2nd electron affinity is always endothermic (positive) because the electron is added to an ion which is already negative therefore it must overcome the repulsion.
Electron Affinity becomes more exothermic across the period because effective nuclear charge increases across the period therefore the shells of electrons are pulled closer to the nucleus so the electron must lose more energy to move closer to the nucleus.
www.revision-notes.co.uk /revision/662.html   (296 words)

  
 Electron Configuration
The electron configuration of an atom is the particular distribution of electrons among available shells.
The number of electrons in an atom of an element is given by the atomic number of that element.
The energy needed to remove the most loosely held electron from an atom is known as ionization energy.
library.thinkquest.org /10429/high/eleconfig/electron.htm   (812 words)

  
 electron affinity   (Site not responding. Last check: 2007-11-03)
Electron affinity is, essentially the opposite of the ionization energy: Instead of removing an electron from the element we add an electron to the element to create an anion.
M + e- ----> M- Generally, the energy that results from this process (the electron affinity) is negative or close to zero.
This periodic trend can be understood as a reflection of the underlying periodicity in the electronic configuration of the elements.
www.iun.edu /~cpanhd/C101webnotes/modern-atomic-theory/electron-affinity.html   (157 words)

  
 AP Chemistry: Atomic Structure   (Site not responding. Last check: 2007-11-03)
You should remember what electron affinity is but don't worry about how it varies as you go across and up and down the periodic table.
If the electron that is lost is the only valence electron so that the electron configuration of the cation is like that of a noble gas, then an entire energy level is lost.
Electrons are further from the nucleus and thus easier to remove the outermost one.
www.chemistrygeek.com /c2c5.htm   (2427 words)

  
 Compton Group Areas of Research
One method to measure the electron affinity that was developed in the process of our research is increasing the electric field used to push out the ions into my mass spectrometer until it was large enough to field ionize the dipole-bound electron.
However, it is difficult to calculate the electron affinities exactly because of tunneling effects and the amount of time that the molecule spends in the electric field.
The electron then has energy that is equal to the energy of the laser less the electron affinity of the anion.
web.utk.edu /~rcompton/dipole.htm   (748 words)

  
 Affinity - Wikipedia, the free encyclopedia
Affinity (canon law), a relationship arising from the sexual intercourse of a man and a woman
Affinity (Fire Emblem), the numerous bonuses units have from sharing support conversations with one another.
Affinity Math - A percentage leaning favorable of 1 set of values over another set pertaining to the same item in the set.
en.wikipedia.org /wiki/Affinity   (181 words)

  
 Electron Affinity and Energy
Electron affinity is exothermic because energy is released when the nucleus attracts an electron.
--------------------------- Zunaria, Electron affinity is the energy change that occurs when an neutral atom in the gaseous state acquires an electron to form a stable negative ion.
Thus, large negative values associated with some electron affinity values indicate that the ion formed is more stable than the free atom and electron which formed it.
www.newton.dep.anl.gov /askasci/chem00/chem00955.htm   (512 words)

  
 Electron Affinity   (Site not responding. Last check: 2007-11-03)
The electron affinity (generally) increases as you move left to right across the periodic table, from the alkali metals to the halogens.
Unlike ionization energy and atomic radii relatively small changes in the electron affinity are observed as you move down a group.
There are enough exceptions to the periodic trends in electron affinity that it is worthwhile to consider electron affinity of specific groups in the periodic table.
www.chemistry.ohio-state.edu /~woodward/ch121/ch7_ea.htm   (245 words)

  
 Chemistry : Chapter 6 : Periodic Trends   (Site not responding. Last check: 2007-11-03)
Electron affinity is the energy involved when an electron is added to a gaseous atom.
Electron affinity values become more negative for atoms further to the right on the periodic table up until the noble gases.
Electron affinity values become more negative (or less positive) for atoms higher on the periodic table.
www.wwnorton.com /chemistry/concepts/chapter6/ch6_1.htm   (576 words)

  
 Chemistry - Electron affinity
In chemistry, electron affinity is the amount of energy absorbed when an electron is added to a neutral isolated gaseous atom to form a gaseous ion with a 1- charge.
However, the noble gases are an exception: they have positive electron affinities.
Electron affinity is influenced by the octet rule.
www.chemistrydaily.com /chemistry/Electron_affinity   (179 words)

  
 Atomic and physical properties of Periodic Table Group 7 (the halogens)
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
The tendency is for the electron affinities to decrease (in the sense that less heat is given out), but the fluorine value is out of line.
The electron affinity is a measure of the attraction between the incoming electron and the nucleus.
www.chemguide.co.uk /inorganic/group7/properties.html   (1530 words)

  
 SparkNotes: Organic Atomic Structure: Ions and Ionic Bonding
When several electrons are removed from an atom, the energy that it takes to remove the first electron is called the first ionization energy, the energy it takes to remove the second electron is the second ionization energy, and so on.
This is because the first electron removed feels the effect of shielding by the second electron and is therefore less strongly attracted to the nucleus.
An atom's electron affinity is the energy change in an atom when that atom gains an electron.
www.sparknotes.com /chemistry/organic1/atomicstructure/section3.rhtml   (737 words)

  
 Electronic Affinities   (Site not responding. Last check: 2007-11-03)
The electron affinity is the energy change associated with an atom or ion in the gas state gaining an electron.
The halogens, which are one electron short of a completely filled p subshell have the greatest attraction for an electron (i.e.
The general trend is for the electron affinity to become increasingly negative (stronger binding of an electron) as we move across each period toward the halogens.
wine1.sb.fsu.edu /chm1045/notes/Periodic/Affinity/Period05.htm   (244 words)

  
 General Chemistry Online: Glossary:
For example, a hydrogen chloride (HCl) molecule is an electric dipole because bonding electrons are on average closer to the chlorine atom than the hydrogen, producing a partial positive charge on the H end and a partial negative charge on the Cl end.
for the addition of one electron to an atom or ion in the gaseous state.
means "2 electrons in the 1s subshell, 2 electrons in the 2s subshell, and 3 electrons in the 2p subshell.
antoine.frostburg.edu /chem/senese/101/glossary/e.shtml   (1830 words)

  
 Electron Affinity   (Site not responding. Last check: 2007-11-03)
------------------------------------------------ Electron affinity is a measure of the attraction an element has for an electron.
Those elements that have a high attraction for electrons, to form a closed shell in the case of the halides have a more negative (i.e.
Metals on the other hand, especially those in group I and II have very little propensity to gain an electron and form an anion.
www.newton.dep.anl.gov /askasci/chem00/chem00336.htm   (127 words)

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