Relationship between electron affinity and electronegativity

relationship between electron affinity and electronegativity

Unlike electronegativity, electron affinity is a quantitative To summarize the difference between the electron affinity of metals and nonmetals. Well, they are talking about the same thing but here are the definitions. Electronegativity is a chemical property that says how well an atom can attract electrons. Can someone explain the difference between electron affinity and electronegativity, or the relationship between the two. I'm having a hard time.

By convention, the negative sign shows a release of energy. When an electron is added to a metal element, energy is needed to gain that electron endothermic reaction. Metals have a less likely chance to gain electrons because it is easier to lose their valance electrons and form cations.

It is easier to lose their valence electrons because metals' nuclei do not have a strong pull on their valence electrons. Thus, metals are known to have lower electron affinities. Group 1 Electron Affinities This trend of lower electron affinities for metals is described by the Group 1 metals: When nonmetals gain electrons, the energy change is usually negative because they give off energy to form an anion exothermic process ; thus, the electron affinity will be negative.

Electron Affinity - Chemistry LibreTexts

Nonmetals have a greater electron affinity than metals because of their atomic structures: Thus, nonmetals have a higher electron affinity than metals, meaning they are more likely to gain electrons than atoms with a lower electron affinity. Group 17 Electron Affinities For example, nonmetals like the elements in the halogens series in Group 17 have a higher electron affinity than the metals.

This trend is described as below. Notice the negative sign for the electron affinity which shows that energy is released. Unlike electronegativity, electron affinity is a quantitative measurement of the energy change that occurs when an electron is added to a neutral gas atom.

Metals like to lose valence electrons to form cations to have a fully stable octet. The electron affinity of metals is lower than that of nonmetals.

Difference Between Electronegativity and Electron Affinity

Nonmetals like to gain electrons to form anions to have a fully stable octet. They release energy exothermic to gain electrons to form an anion; thus, electron affinity of nonmetals is higher than that of metals.

Notice that electron affinities can be both negative and positive. Image used with permission from Robert J.

relationship between electron affinity and electronegativity

Lancashire University of the West Indies. Patterns in Electron Affinity Electron affinity increases upward for the groups and from left to right across periods of a periodic table because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons. Remember that greater the distance, the less of an attraction; thus, less energy is released when an electron is added to the outside orbital. In addition, the more valence electrons an element has, the more likely it is to gain electrons to form a stable octet.

The less valence electrons an atom has, the least likely it will gain electrons. Electron affinity decreases down the groups and from right to left across the periods on the periodic table because the electrons are placed in a higher energy level far from the nucleus, thus a decrease from its pull. However, one might think that since the number of valence electrons increase going down the group, the element should be more stable and have higher electron affinity. One fails to account for the shielding affect.

As one goes down the period, the shielding effect increases, thus repulsion occurs between the electrons. This is why the attraction between the electron and the nucleus decreases as one goes down the group in the periodic table. As you go down the group, first electron affinities become less in the sense that less energy is evolved when the negative ions are formed. Fluorine breaks that pattern, and will have to be accounted for separately.

The electron affinity is a measure of the attraction between the incoming electron and the nucleus - the stronger the attraction, the more energy is released.

The factors which affect this attraction are exactly the same as those relating to ionization energies - nuclear charge, distance and screening.

  • What is the difference between electronegativity and electron affinity?

The increased nuclear charge as you go down the group is offset by extra screening electrons. Chlorine A fluorine atom has an electronic structure of 1s22s22px22py22pz1. It has 9 protons in the nucleus. The incoming electron enters the 2-level, and is screened from the nucleus by the two 1s2 electrons. In contrast, chlorine has the electronic structure 1s22s22p63s23px23py23pz1 with 17 protons in the nucleus.

There is also a small amount of screening by the 2s electrons in fluorine and by the 3s electrons in chlorine. This will be approximately the same in both these cases and so does not affect the argument in any way apart from complicating it! The over-riding factor is therefore the increased distance that the incoming electron finds itself from the nucleus as you go down the group. The greater the distance, the less the attraction and so the less energy is released as electron affinity.

Comparing fluorine and chlorine is not ideal, because fluorine breaks the trend in the group. However, comparing chlorine and bromine, say, makes things seem more difficult because of the more complicated electronic structures involved.

What we have said so far is perfectly true and applies to the fluorine-chlorine case as much as to anything else in the group, but there's another factor which operates as well which we haven't considered yet - and that over-rides the effect of distance in the case of fluorine.

Why is Fluorine an Anomaly? The incoming electron is going to be closer to the nucleus in fluorine than in any other of these elements, so you would expect a high value of electron affinity. Electronegativity causes a bond between two atoms to be polar. If one atom is more electronegative than the other atom, the atom with the higher electronegativity can attract electrons of the bond. This cause the other atom to have a partial positive charge due to lack of electrons around it.

Therefore, electronegativity is the key to classify chemical bonds as polar covalent, nonpolar covalent and ionic bonds. Ionic bonds occur between two atoms with a huge difference in electronegativity between them whereas covalent bonds occur between atoms with a slight difference in electronegativity between the atoms.

The electronegativity of elements varies periodically. The periodic table of elements has a better arrangement of elements according to their electronegativity values. Periodic Table of Elements along with Electronegativity of Elements When considering a period in the periodic table, the atomic size of each element decreases from left to right of the period.

This is because the number of electrons present in the valence shell and the number of protons in the nucleus are increased, and thus, the attraction between electrons and the nucleus is increased gradually.

Therefore, the electronegativity is also increased along the same period because the attraction that comes from the nucleus is increased. Then the atoms can easily attract electrons from the outside.

Electron Affinity

Electronegativity XP from top to bottom of each group The group 17 has the smallest atoms of each period, so it has the highest electronegativity.

But the electronegativity decreases down the group because the atomic size increases down the group due to increasing the number of orbitals. What is Electron Affinity Electron affinity is the amount of energy released when a neutral atom or molecule in the gaseous phase gains an electron from outside. This electron addition causes the formation of a negatively charged chemical species.

relationship between electron affinity and electronegativity

This can be represented by symbols as follows. This is called exothermic reaction. This reaction results in a negative ion.

What is the difference between electronegativity and electron affinity? | Socratic

But if another electron is going to be added to this negative ion, energy should be given in order to proceed with that reaction. This is because the incoming electron is repelled by the other electrons.

This phenomenon is called endothermic reaction. Therefore, the first electron affinities are negative values and the second electron affinity values of the same species are positive values. This is because the incoming electron is added to the outermost orbital of an atom. The elements of the periodic table are arranged according to the ascending order of their atomic number. When the atomic number increases, the number of electrons they have in their outermost orbitals increases.