So the more negative the electron affinity the more favorable the electron addition process is. The electron affinity ea is defined as the energy difference between the 3 p ground state of the boron anion b. In general successive electron affinity increase in magnitude ea 1 electrons within an atom exist in states defined by four quantum numbers. Electron affinity is the amount of energy required to detach one electron from a negatively charged ion of an atom or molecule. Unlike electronegativity, electron affinity is a quantitative measurement of the energy change that occurs when an electron is added to a neutral gas atom. Electron affinity is a measure of the energy released when an extra electron is added to an atom. Electron affinity is the energy change that results from adding an electron to a gaseous atom. In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as. Energy of an atom is defined when the atom loses or gains energy through chemical reactions that cause the. First, heres a primer from my answer to a similar question about noble gases 1. Electron affinity ea refers to the energy released when an atom in the gas phase accepts an electron.
The adiabatic electron affinity is given by the difference between the energy of the neutral system li n, at its most stable geometry, and of the anionic li n cluster, also at its most stable conformation. Halogens are the higher in electron affinity, and chlorine has the higher electron. The electron affinity, a measure of the energy released when an atom gains an electron an exothermic reaction, increases from left to right across the periodic table because when a smaller atom gains an electron, the force between the electron and nucleus is greater than with a. Periodic table trends electron affinity with worked. A more negative electron affinity corresponds to a greater attraction for an electron. Electron affinity follows a trend on the periodic table. 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. Electronegativity cannot be measured and needs to be computed from other atomic properties by a few differing equations depending on which scientist you adhere to 5. In other words, the neutral atoms likelihood of gaining an electron. We have calculated the ea employing a previous calculation of the ground state of boron atom using the same methodology and computer program but a smaller basis set and smaller number of. The electron affinity ea of an element is the energy change that occurs when an electron is added to a gaseous atom to give an anion.
Because youre creating a bond between the atom and this new incoming electron. Electron affinity is a fixed and measurable value 4. What are the trends and exceptions to the trends in. The energy released when an electron is added to a gaseous atom which is in its ground state to form a gaseous negative ion is defined as the first electron affinity.
It increases moving down a column or group and also increases moving from left to right across a row or period except for the noble gases. Were going to say were adding an electron to something, so were creating new bonds. Nature is messy here, but in general metals have a low ea, nonmetals are higher. Metals like to lose valence electrons to form cations to have a fully stable shell. Sep 27, 2017 this chemistry video tutorial provides a basic introduction into electron affinity. Answer electron affinity is the energy released when we add an electron to the outermost orbit of the atom. Electron affinity in a horizontal period increases from. Referring back to general trends of the electron affinity. As with ionization energy, there are two rules that govern the periodic trends of electron affinities. Ionization energy is measured by the energy unit kilojoules per mole, or kjmol. As the name suggests, electron affinity is the ability of an atom to accept an electron. At the conclusion of this twoday lesson students will be familiar with the trends in the periodic table.
In general successive electron affinity increase in magnitude ea 1 electron affinity increases across the period. The second reverse definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion. Worksheet 12 periodic trends ionization electron affinity. Rotate to landscape screen format on a mobile phone or small tablet to use the mathway widget, a free math problem solver that answers your questions with stepbystep. Electronegativity vs electron affinity chemistry community. In general, electron affinities become less negative from top to bottom of a group. Ukanteach lesson plan format periodic trends authors. Therefore, electron affinity will also increase on moving from left to right. The electron affinity of fluorine is the enthalpy change for reaction 5141 at 0 k.
This affinity is known as the second electron affinity and these energies are positive. Electron affinity definition, trend, equation and electron. May 18, 2018 ionization energy trend refers to the energy needed to displace an electron from a given atom, or the amount of energy required to remove an electron from an ion, or gaseous atom. The general trend for electron affinity down the group is that it decreases because of the increase in atomic radius. This is because the desire to gain an electron increases the closer you get to fill the energy level. Electrons within an atom exist in states defined by four quantum numbers. Electron affinity, electronegativity and electrophilicity are three related chemical concepts. The electron affinity of an atom or molecule is the amount of energy released or spent when an electron is added to a neutral atom or molecule in the. Write out the expanded and condensed electron configurations for each of. Among these properties are ionization energy, electron affinity and atomic ionic radii. Therefore, the electron affinity of an nelectron system is given by. The main difference between electronegativity and electron affinity is that electronegativity is the ability of an atom to attract electrons from the outside whereas electron affinity is the amount of energy released when an atom gains an electron. In solid state physics, the electron affinity for a surface is defined somewhat differently see below.
Electron affinity is the ability of an atom to attract and hold an extra electron. Electron affinity can reflect the ability of an atom to gain electrons. Electron affinity, electronegativity and electrophilicity. Nitrogen electron affinity electronegativity ionization. The smaller the first electron affinity, the easier an atom gains electrons.
They have the same trend increase as you go across and decrease as you go down the periodic table. Are there any major exceptions when comparing electron. Electronegativity values relate to the ability of an atom. Periodic trends in electron affinity chemistry socratic. In general, elements with the most negative electron affinities the highest affinity for an added electron are those with the smallest size and highest ionization energies and are located in the upper right corner of the periodic table. For maingroup elements, electron affinity generally becomes more positive as you move to the right across a rowc.
Electron affinity is the amount of energy that is released when an electron attaches to the atom 3. Electron affinity, electronegativity, ionization energy. The reason why there is not a corresponding trend in electron affinity going down a column is because, for the most part, the charge of a specific group on the periodic table has the same charge. Electron affinity, ionization energy and electronegativity. Notice that the 1st electron affinity of fluorine does not follow the group trend. The more negative the electron affinity value, the higher an atoms affinity for electrons. Electron affinity becomes less negative down a group. Thus, we can conclude that the trends and exceptions to. A negative electron affinity means energy must be input in order to attach an electron to the ion. The electron affinity also does not follow the trend from group 1 to 2, and 14 to 15, because the gain of an additional electron results in a less stable or more unfavorable electron configuration. Covers the definition of electron affinity and trends in electron affinity. There is a great amount of information that you can benefit from knowing about electron affinity, and this quiz and worksheet will test your understanding of this concept. Electron affinity trend, basic introduction, chemistry youtube.
Students should be able to guess that it is hardest to remove an electron from he. The greater the electron affinity, the weaker is the ability of an atom to gain electrons. Moving from left to right and bottom to top on the period table, electron affinity increases. In other words, lower ea less likely to accept an electron. As elements of group 15 are half filled so, they are more stable in nature and have slightly less electron affinity as compared to group 14 elements. Trends, ioniztion, electron affinity flashcards quizlet. Worksheet 12 periodic trends a number of physical and chemical properties of elements can be predicted from their position in the periodic table. For example, when a fluorine atom in the gaseous state gains an electron to form f. Nov 14, 2017 the electron affinity ea is the energy released to add an electron to an elements in the gaseous state.
Since this electron is farther away, it should be less attracted to the nucleus and release less energy when added. The electrons are pulled closer to the nucleus making the atom smaller. The electron affinity of metals is lower than that of nonmetals. Electron affinity follows the trend of electronegativity. This chemistry tutorial describes the concept of electron affinity and covers the general periodic trend of electron affinity along with notable exceptions in this trend. The measure of energy released or required when you add an electron onto a neutral, gaseous atomforming a negative ion. The number of energy shells increases and the electron is faced with more inter electron repulsion as it approaches.
Electron affinity is defined as the change in energy in kjmole of a neutral atom in the gaseous phase when an electron is added to the atom to form a negative ion. In general, electron affinities become more negative as we move from left to right on the periodic table. The electron affinity eea of an atom or molecule is defined as the amount of energy released or spent when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion. Electron affinity is the opposite, its the energy thats required to place an electron onto something. These properties all involve the outer shell valence electrons as well as the inner shell shielding. Determine which orbital of the pair has the highest energy and explain your reasoning. They will be able to predict element properties based on their location in the periodic table. Electronegativity, electron affinity, atomic radius, atomic mass, ionization energy objectives. For maingroup elements, electron affinity generally becomes more negative as you move to the right across a rowb.
This is because going from left to right and bottom to top, the atomic radius decreases so it is easier for the nucleus to attract negative electrons. What are the observed periodic trends in electron affinity. Electron affinity is the attraction a neutral atom has for a nonbonding electron. The electron affinity decreases on descending a group.
May 14, 2018 the electron affinity trend describes the trend across the periodic table and describes how much energy in an atom is released or spent when an electron is added to a neutral atom or the energy change that occurs when an electron is added to a neutral atom. In general, a greater electron affinity implies a lower tendency of the atom to accept an extra electron. Electronegativity is the tendency of an atom to attract electrons, while electron affinity is the amount of energy released when an electron is added to a neutral atom. Electron affinity, electronegativity, ionization energy 1. This chemistry video tutorial provides a basic introduction into electron affinity. The ionization energy shows the ability of an atom to loose its electrons. This is because going from left to right and bottom to top, the atomic radius decreases so it is easier for. 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 electron affinity trend describes the trend across the periodic table and describes how much energy in an atom is released or spent when an electron is added to a neutral atom or the energy change that occurs when an electron is added to a neutral atom. This is because its easier for small atoms with the nucleus closer to the outer electrons to gain another electron. Electron affinities are measured in the gaseous state. Jul 09, 2017 the main difference between electronegativity and electron affinity is that electronegativity is the ability of an atom to attract electrons from the outside whereas electron affinity is the amount of energy released when an atom gains an electron. The electron affinity e ea of a neutral atom or molecule is defined as the amount of energy released when an electron is added to it to form a negative ion, as demonstrated by the following equation. There is not a corresponding trend in electron affinity going right across a rowd.
The electron affinity trend describes the trend across the periodic table and describes how much energy in an atom is released or spent when an electron is added to a neutral atom or the energy change that occurs when an electron is added to a neutral atom the electron affinity trend describes how as one follows the periodic table left to right electron affinity increases and how it. Within the halogen, at, or astatine has the least negative electron. Electron affinity an overview sciencedirect topics. They will be able to predict element properties based. The observed periodic trends in electron affinity are that electron affinity will generally become more negative, moving from left to right across a period, and that there is no real corresponding trend in electron affinity moving down a group in the periodic table. The number of energy shells increases and the electron is faced with more interelectron repulsion as it approaches. Electron affinity, electronegativity and electrophilicity of. Electron affinity can be defined in two equivalent ways. Sodium, aluminum, phosphorus, and chlorine are all in the same row period of the periodic table. Because this value is negative energy is released, we say that the electron affinity of fluorine is favorable. Electron affinity trends look at this link on electronegativity trends.
Notice that the period 3 elements actually have the greatest electron affinities, instead of the period 2 elements as the trend suggests. The electron affinity is the potential energy change of the atom when an electron is added to a neutral gaseous atom to form a negative ion. First, as the energy that is released by adding an electron to an isolated gaseous atom. Because of electron electron repulsions, this is energetically unfavorable, making the electron affinity more positive.
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