Electron affinities of inert gases are zero. This is due to the small tendency to accept another electron.
Electron affinity is almost zero or low in elements having a stable electronic configuration. Therefore, it will face a lower value of its electron affinity. In general, too, the electronic affinity increases by going down the group and decreases from left to right across the periods.Įlectronic Configuration: Stable the configuration of an atom, its tendency will be less to accept the electron. Therefore, the value of electron affinity will be small. This will result in a smaller force of attraction by electrons. Therefore, the greater the pull of the nucleus, the greater the chance of electrons attaching to the atom.Ītomic Size : The larger the size of an atom, the larger will be the distance between the nucleus and electron. To explain it in simpler terms, the nuclear charge can be understood as the pull that is exerted by the nucleus on the electrons. This will result in a larger value of electron affinity. Nuclear Charge: The greater the nuclear charge, the greater will be the attraction of the incoming electron. The three factors affecting the electron affinity of a molecule are Nuclear Charge, Atomic Size, and Electronic Configuration. These factors are generally related to the structure and configuration of the molecule in question. It 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.Įlectron Affinity is affected by three main factors. Second electron affinity is only met concerning the group 16 elements oxygen and sulfur which both form -2 ions. The electron affinity trend is stated below:
#Mha crossover series
It is rather easy to attract an electron from another element.Įxample: Non-metals like the elements in the Halogen series in Group 17 have higher electron affinity. The valence electron shell is closer to the nucleus, this makes it harder to remove an electron. Non-metals have more valence electrons than metals have which makes it easy to gain electrons to fulfill a stable octet. There are two reasons associated with why non-metals have greater electron affinity. Non-metals have greater electron affinity because of their atomic structures. When nonmetals gain electrons, the energy change noted is negative because they give off energy. The Trend of Lower Electron Affinities For Metals is described by Group 1 Therefore, metals are said to have lower electron affinities. The reason behind losing their valence electrons is that metals’ nuclei do not have a strong pull on their valence electrons. However, metals are less likely to gain electrons as it is easier to lose their valence electrons and form cations. Example: The first electron affinity of chlorine is -349 kJ mol⁻¹ The energy is needed to gain the electron when an electron is added to a metal element. The first electron affinity is the energy released when 1 mole of gaseous atoms acquire an electron to form 1 mole of gaseous -1 ions. Second Electron Affinity: Positive energy because the energy needed is more than gained.įirst Electron Affinity: The energies are always concerned by the formation of positive ions. Negative energy because energy is released. The electron affinity is further discussed below: Thus first electron affinities are always negative whereas second electron affinity ( electron to negative ion ) is positive. The energy is released when an electron is being added to a neutral atom. Hence, given a positive sign whereas energy from an exothermic reaction is negative. Talking about energies, energy from an endothermic reaction is positive. The reaction that releases energy is called an ‘exothermic’ reaction and the reaction in which energy is absorbed is called an ‘endothermic’ reaction. The energy of an atom is stated when an atom loses or gains energy through chemical reactions that cause the loss or gain of electrons. The more negative the electron affinity value, the higher an atom’s affinity for electrons. Electron affinity is defined as the quantitative measurement of the energy change that results from adding a new electron to a neutral atom or molecule in the gaseous state.
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