What is the difference between electronegativity and electron affinity? | Socratic
Electron affinity is defined as the change in energy (in kJ/mole) of a neutral always confined to elements in groups 16 and 17 of the Periodic Table. To summarize the difference between the electron affinity of metals and. Ionization energy: the energy required to remove an electron from a neutral atom. Groups VIA and VIIA in the periodic table have the largest electron affinities. The difference between the electronegativities of Na() and Cl() are so. Electronegativity vs Electron Affinity The transfer of one electron from one atom to another is a very common occurrence that we do not notice.
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.
Electron Affinity vs Electronegativity - CHEMISTRY COMMUNITY
The electron affinity of metals is lower than that of nonmetals. Nonmetals like to gain electrons to form anions to have a fully stable octet.
- Difference Between Electronegativity and Electron Affinity
- What is the difference between electronegativity and electron affinity?
- Electron Affinity
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. 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. 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. The electronegativities of other atoms are given a value considering their capabilities of attracting electrons.
Electronegativity depends on the atomic number and the size of the atom in an element. When considering the periodic table, Fluorine F is given the value 4. Thus, it can attract electrons from the outside easily. In addition, the atomic number of Fluorine is 9; it has a vacant orbital for one more electron, in order to obey the octet rule.
Therefore, Fluorine readily attracts electrons from outside. 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.
Electron Affinity - Chemistry LibreTexts
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. Therefore, electron affinity decreases.
Moving from left to right across a period, atoms become smaller as the forces of attraction become stronger. This causes the electron to move closer to the nucleus, thus increasing the electron affinity from left to right across a period. Note Electron affinity increases from left to right within a period. This is caused by the decrease in atomic radius.
Electron affinity decreases from top to bottom within a group. This is caused by the increase in atomic radius.
Atomic Radius Trends The atomic radius is one-half the distance between the nuclei of two atoms just like a radius is half the diameter of a circle. However, this idea is complicated by the fact that not all atoms are normally bound together in the same way. Some are bound by covalent bonds in molecules, some are attracted to each other in ionic crystals, and others are held in metallic crystals.
Nevertheless, it is possible for a vast majority of elements to form covalent molecules in which two like atoms are held together by a single covalent bond. This distance is measured in picometers. Atomic radius patterns are observed throughout the periodic table. Atomic size gradually decreases from left to right across a period of elements.
This is because, within a period or family of elements, all electrons are added to the same shell. However, at the same time, protons are being added to the nucleus, making it more positively charged. The effect of increasing proton number is greater than that of the increasing electron number; therefore, there is a greater nuclear attraction. This means that the nucleus attracts the electrons more strongly, pulling the atom's shell closer to the nucleus.
The valence electrons are held closer towards the nucleus of the atom. As a result, the atomic radius decreases. The valence electrons occupy higher levels due to the increasing quantum number n.
Note Atomic radius decreases from left to right within a period. This is caused by the increase in the number of protons and electrons across a period. Atomic radius increases from top to bottom within a group. This is caused by electron shielding. Melting Point Trends The melting points is the amount of energy required to break a bond s to change the solid phase of a substance to a liquid.
Because temperature is directly proportional to energy, a high bond dissociation energy correlates to a high temperature.