How does electron affinity increase

Looking to get ready for the ACT? We can help with ACT Prep. This article was written for you by Samantha , one of the tutors with Test Prep Academy. Login Get started. ACT Science. School Tutoring October 26, No Comments. Going Up and Down Groups Columns When moving down a group, the electron affinity generally decreases.

Summary: Electron affinity deceases as you do down a column because of the increase in atomic radius from the addition of a new valence electron shell. You might also like.

The second EA is the energy associated with adding an electron to an anion to form a 2— ion, and so on. As one might predict, it becomes easier to add an electron across a series of atoms as the effective nuclear charge of the atoms increases. As we go from left to right across a period, EAs tend to become more negative. The exceptions found among the elements of group 2 2A , group 15 5A , and group 18 8A can be understood based on the electronic structure of these groups.

The noble gases, group 18 8A , have a completely filled shell, and the incoming electron must be added to a higher n level, which is more difficult to do. Group 2 2A has a filled ns subshell, and so the next electron added goes into the higher energy np , so, again, the observed EA value is not as the trend would predict.

Finally, group 15 5A has a half-filled np subshell, and the next electron must be paired with an existing np electron. In all of these cases, the initial relative stability of the electron configuration disrupts the trend in EA.

One might expect the atom at the top of each group to have the most negative EA; their first ionization potentials suggest that these atoms have the largest effective nuclear charges. However, as we move down a group, we see that the second element in the group most often has the most negative EA.

The electron is attracted to the nucleus, but there is also significant repulsion from the other electrons already present in this small valence shell.

The entering electron does not experience as much repulsion, and the chlorine atom accepts an additional electron more readily, resulting in a more negative EA.

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If you have any questions, please do not hesitate to reach out to our customer success team. Login processing Chapter 8: Periodic Properties of the Elements. Chapter 1: Introduction: Matter and Measurement. Chapter 2: Atoms and Elements. Chapter 3: Molecules, Compounds, and Chemical Equations. Chapter 4: Chemical Quantities and Aqueous Reactions. Chapter 5: Gases. Chapter 6: Thermochemistry. How can electron affinity be negative?

What is electron affinity? Why is the electron affinity for nitrogen positive? Question Which following pairs of atoms, have a lower electron affinity? Question 6a8b4. See all questions in Periodic Trends in Electron Affinity. Impact of this question views around the world. You can reuse this answer Creative Commons License. Fluorine is much more reactive than chlorine despite the lower electron affinity because the energy released in other steps in its reactions more than makes up for the lower amount of energy released as electron affinity.

You are only ever likely to meet this with respect to the group 16 elements oxygen and sulfur which both form -2 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. This is more easily seen in symbol terms. Why is energy needed to do this? You are forcing an electron into an already negative ion. It's not going to go in willingly!

The positive sign shows that you have to put in energy to perform this change. The second electron affinity of oxygen is particularly high because the electron is being forced into a small, very electron-dense space.

Jim Clark Chemguide. Introduction Energy of an atom is defined when the atom loses or gains energy through chemical reactions that cause the loss or gain of electrons. First Electron Affinity Ionization energies are always concerned with the formation of positive ions.

Nonmetals vs. They absorb energy endothermic to lose electrons. The electron affinity of metals is lower than that of nonmetals. Nonmetals: 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. 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.

Chlorine A fluorine atom has an electronic structure of 1s 2 2s 2 2px 2 2py 2 2pz 1. Why is Fluorine an Anomaly? Second Electron Affinity You are only ever likely to meet this with respect to the group 16 elements oxygen and sulfur which both form -2 ions.

Practice Problems When an electron is added to a nonmetal atom, is energy released or absorbed? Why do nonmetal atoms have a greater electron affinity than metal atoms? Why are atoms with a low electron affinity more likely to lose electrons than gain electrons? As you move down a group of the periodic table, does electron affinity increase or decrease, if so, why?

Why do nonmetals want to gain electrons?