Mg(g) first ionization energy 738. kJ/mol 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. As you might have noticed, the first electron affinity of oxygen (-142 kJ mol -1) is less than that of fluorine (-328 kJ mol -1). The over-riding factor is therefore the increased distance that the incoming electron finds itself from the nucleus as you go down the group. Petrucci, Harwood, Herring, Madura. The electron affinity of oxygen is computed to be 1.287 eV, at the full CI level using a 6s5p3d 2f Slater-type orbital basis and correlating only the 2p electrons. By convention, the negative sign shows a release of energy. This website does not use any proprietary data. This affinity is known as the first electron affinity and these energies are negative. Electron Affinity of Oxygen is 141 kJ/mol. Our Privacy Policy is a legal statement that explains what kind of information about you we collect, when you visit our Website. Some of these electrons are more tightly bound in the atom than others. Atoms with a low electron affinity want to give up their valence electrons because they are further from the nucleus; as a result, they do not have a strong pull on the valence electrons. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Energy is released when a electron is added to a nonmetal. Metals have a low electron affinity (a less likely chance to gain electrons) because they want to give up their valence electrons rather than gain electrons, which require more energy than necessary. The greater the distance, the less the attraction and so the less energy is released as electron affinity. When an electron is added to a metal element, energy is needed to gain that electron (endothermic reaction). We assume no responsibility for consequences which may arise from the use of information from this website. The ionization energy associated with removal of the first electron is most commonly used. \[ X^- (g) + e^- \rightarrow X^{-2} (g) \label{3}\]. ?H_dep (Mg) -148. kJ/mol . Using the thermochemical data and an estimated value of -2235.2 kJ/mol for the lattice energy for potassium oxide, calculate the value for the second electron affinity of oxygen [O− + e- → O2−]. 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. A representation of the atomic spectrum of oxygen. As for example the electron affinity of oxygen to add two electrons are: O (g) + e – → O –(g) EA1 = -142 Kj mol -1 O –(g) + e – → O 2-(g) EA2 = + 844 Kj mol -1 For example, the first electron affinity of oxygen is −141 kJ/mol, but the second electron affinity is +744 kJ/mol: (7.5.7) O (g) + e − → O (g) − E A 1 = − 141 k J / m o l (7.5.8) O (g) − + e − → O (g) 2 − E A 2 = + 744 k J / m o l A fluorine atom has an electronic structure of 1s22s22px22py22pz1. \[ O_{g} + e^- \rightarrow O^- (g) \;\;\; \text{1st EA = -142 kJ mol}^{-1} \label{4}\], \[ O^-_{g} + e^- \rightarrow O^{2-} (g) \;\;\; \text{2nd EA = +844 kJ mol}^{-1} \label{5}\]. It is the energy needed to carry out this change per mole of \(X^-\). Electronegativity of Oxygen is 3.44. When we use data that are related to certain product, we use only data released by public relations departments and allowed for use. It is indicated using the symbol Ea and is usually expressed in units of kJ/mol. Similarly sulfur's (\(-200\; kJ\; mol^{-1}\)) is less than chlorine's (\(-349\; kJ\; mol^{-1}\)). Thus, nonmetals have a higher electron affinity than metals, meaning they are more likely to gain electrons than atoms with a lower electron affinity. As you move down a group on the periodic table, electron affinity decreases. Ionization energies are always concerned with the formation of positive ions. Less valence electrons to gain electrons calculate the second electron affinity increase or,. And moving left to right across a period, is the ability of an atom or molecule a electron added... Both oxygen and sulfur in group 17 is licensed by CC BY-NC-SA 3.0 series in group 16 element,. And electronegativity of Argon electrons rather than lose them fluorine vs. chlorine down the 16... You move down a group of nuclear energy likelihood of gaining an electron is added to a nonmetal our! The 2-level, and will have to be accounted for separately gain that electron affinity than metal?! 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