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? Why do metals have a low electron affinity? Answers Energy is released when a electron is added to a nonmetal.
Nonmetals have a greater electron affinity than metals because their atomic structure allows them to gain electrons rather than lose them. 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. As you move down a group on the periodic table, electron affinity decreases.
First, the electrons are placed in energy levels further away from the nucleus, which results in electrons not having a strong attraction to the nucleus; secondly, the atom does not want gain electrons because there is minimal charge on the outer energy levels from the nucleus; and lastly, the shielding effect increases, causing repulsion between the electrons, thus they move further from each other and the nucleus itself.
Nonmetals want to gain electrons because they have more valence electrons than metals, so it is easier for them to gain electrons than lose the valance electrons to fulfill a stable octet. In addition, nonmetals' valance electrons are closer to the nucleus, thus allowing more attraction between the two. 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.
In addition, they do not have a strong pull on the valance electrons because they are far away from the nucleus, thus they have less energy for an attraction. References Petrucci, Harwood, Herring, Madura.
Prentice Hall. Argon, however, has a positive electron affinity, indicating that formation of an argon anion requires energy to be supplied.
In general, the greater the attraction between an atom and an added electron, the more negative the electron affinity. Electron affinities, similar to ionization energies, show trends in the periodic table.
Moving down group 1, the atomic size increases as the electrons occupy higher principal quantum numbers. Incoming electrons, therefore, experience less nuclear attraction leading to less negative electron affinities. However, there are exceptions. In halogens, chlorine has a more negative electron affinity value than fluorine.
But why? Fluorine is the smallest atom of the halogens and an incoming electron experiences a significant repulsion from the electrons already present. In the chloride anion, however, the new electron is added into the third shell, occupying more space.
This reduces the electron-electron repulsions, making it more attractive for an electron to be gained. Generally, moving across a period, electron affinities become more negative. Halogens have the most negative electron affinities, as the incoming electron helps to achieve noble gas configurations.
In comparison, noble gases have a completely filled shell. The incoming electron has to be accommodated in the higher principal energy level, which is energetically unfavorable. Thus, electron affinities for these elements are positive. Group 2 shows exceptions.
The electron configuration indicates that the incoming electron needs to enter a higher-energy subshell. Thus, electron affinity values are either positive or less exothermic. Interestingly, group 15 has less negative electron affinities than group Compare phosphorus and silicon. Unlike silicon, phosphorus has a half-filled p -subshell and the incoming electron needs to be paired with an electron already residing in the p -orbital.
This would increase the electron-electron repulsions and is therefore an energetically unfavourable process, which is also reflected in the less negative electron affinity compared to silicon. The electron affinity EA is the energy change for adding an electron to a gaseous atom to form an anion negative ion. This process can be either endothermic or exothermic, depending on the element.
Many of these elements have negative values of EA, which means that energy is released when the gaseous atom accepts an electron.
References G. Tehan, B. Barnett and J. See: M. More about February Read More. Chem13 news magazine. It has the symbol Hf. Lutetium Lu is a silvery-white coloured metal that has the atomic number 71 in the periodic table. It is a Lanthanide metal.
It has the symbol Lu. Ytterbium Yb is a silvery coloured metal that has the atomic number 70 in the periodic table. It has the symbol Yb. Thulium Tm is a silvery coloured metal that has the atomic number 69 in the periodic table. It has the symbol Tm.
Erbium Er is a silvery coloured metal that has the atomic number 68 in the periodic table. It has the symbol Er. Holmium Ho is a silvery coloured metal that has the atomic number 67 in the periodic table. It has the symbol Ho. Dysprosium Dy is a silvery coloured metal that has the atomic number 66 in the periodic table.
It has the symbol Dy. Terbium Tb is a silvery-gray coloured metal that has the atomic number 65 in the periodic table. It has the symbol Tb. Gadolinium Gd is a silvery-white coloured metal that has the atomic number 64 in the periodic table. It has the symbol Gd. Europium Eu is a silvery-white coloured metal that has the atomic number 63 in the periodic table.
It has the symbol Eu. Samarium Sm is a silvery coloured metal that has the atomic number 62 in the periodic table. It has the symbol Sm. Promethium Pm is a rare metal that has the atomic number 61 in the periodic table. It has the symbol Pm. Neodymium Nd is a silvery white coloured metal that has the atomic number 60 in the periodic table. It has the symbol Nd. Praseodymium Pr is a silvery white coloured metal that has the atomic number 59 in the periodic table.
It has the symbol Pr. Cerium Ce is a iron-gray coloured metal that has the atomic number 58 in the periodic table. It has the symbol Ce. Lanthanum La is a soft silvery white coloured metal that has the atomic number 57 in the periodic table.
It has the symbol La. Barium Ba is a soft silvery white coloured metal that has the atomic number 56 in the periodic table. It is an Alkaline earth metal and is located in Group 2 of the periodic table. Caesium Cs is a soft gray coloured metal that has the atomic number 55 in the periodic table. It is an Alkali Metal and is located in Group 1 of the periodic table.
Xenon Xe exists as a colourless, odourless gas and is chemically inert. It has the atomic number 54 in the periodic table and belongs in Group 18, the Noble Gases. It is a non metal with the symbol Xe. Iodine I is a purple grey solid non metal. It has the atomic number 53 in the periodic table. It is located in Group 17, the Halogens. It has the symbol I.
Tellurium Te is a silver-white semi metal that has the atomic number 52 in the periodic table. It is located in Group 16 of the periodic table. It has the symbol Te. Antimony Sb is a hard brittle silver-white semi metal that has the atomic number 51 in the periodic table. It is located in Group 15 of the periodic table. It has the symbol Sb. Tin Sn is a silver-white metal that has the atomic number 50 in the periodic table.
It is located in Group 14 of the periodic table. It has the symbol Sn. Indium In is a silver-white metal that has the atomic number 49 in the periodic table. It is located in Group 13 of the periodic table. It has the symbol In. Cadmium Cd is a blue-white metal that has the atomic number 48 in the periodic table. It is a Transition metal and located in Group 12 of the periodic table.
It has the symbol Cd. Silver Ag is a silver metal that has the atomic number 47 in the periodic table. It is a Transition metal and located in Group 11 of the periodic table.
It has the symbol Ag. Palladium Pd is a silver-white metal that has the atomic number 46 in the periodic table. It is a Transition metal and located in Group 10 of the periodic table.
It has the symbol Pd. Rhodium Rh is a brittle silver-white metal that has the atomic number 45 in the periodic table. It is a Transition metal and located in Group 9 of the periodic table. It has the symbol Rh. Ruthenium Ru is a brittle silver-gray metal that has the atomic number 44 in the periodic table. It is a Transition metal and located in Group 8 of the periodic table. It has the symbol Ru. Technetium Tc is a silvery-gray metal that has the atomic number 43 in the periodic table.
It is a Transition metal and located in Group 7 of the periodic table. It has the symbol Tc. Molybdenum Mo is a silvery-white metal that has the atomic number 42 in the periodic table.
It is a Transition metal and located in Group 6 of the periodic table. It has the symbol Mb. Niobium Nb is a shiny white metal that has the atomic number 41 in the periodic table. It is a Transition metal and located in Group 5 of the periodic table. It has the symbol Nb. Zirconium Zr is a gray white metal that has the atomic number 40 in the periodic table.
It is a Transition metal and located in Group 4 of the periodic table. It has the symbol Zr. Yttrium Y is a silvery metal that has the atomic number 39 in the periodic table.
It is a Transition metal and located in Group 3 of the periodic table. It has the symbol Y. An ion is the term used to describe an atom that has either lost or gained an electron so that it is charged.
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