electron affinity vs electronegativity?

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electron affinity vs electronegativity?

Postby BriannaParrington-1B » Sat May 12, 2018 12:40 pm

Hello, can someone please explain to me the difference between electron affinity and electronegativity? What makes them different and what are their trends?

Jack Martinyan 1L
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Re: electron affinity vs electronegativity?

Postby Jack Martinyan 1L » Sat May 12, 2018 1:56 pm

Electronegativity is the ability of an atom to attract electrons from outside. This is a qualitative property of an atom, and in order to compare the electronegativities of atoms in each element, a scale where relative electronegativity values reside is used. This scale is called “Pauling scale.” According to this scale, the highest electronegativity value that an atom can have is 4.0. 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. 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. As you move down a group on the periodic table, the electronegativity of an element decreases because the increased number of energy levels puts the outer electrons very far away from the pull of the nucleus. Electronegativity increases as you move from left to right across a period on the periodic table.Electron affinity is the amount of energy released when a neutral atom or molecule (in the gaseous phase) gains an electron from outside. Same as electronegativity, electron affinity also shows periodic variation in the periodic table. This is because the incoming electron is added to the outermost orbital of an atom. The elements of the periodic table are arranged according to the ascending order of their atomic number. When the atomic number increases, the number of electrons they have in their outermost orbitals increases. In general, the electron affinity should increase along the period from left to right because the number of electrons increases along a period; thus, it is difficult to add a new electron.

Michael Park
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Re: electron affinity vs electronegativity?

Postby Michael Park » Sun May 13, 2018 7:02 pm

Electron affinity is the energy required to add an electron to a neutral atom.

Electronegativity is the tendency of an atom to attract electrons toward itself; higher electronegativity means more energy is required to "take away" the electron. For example, fluorine is the most electronegative element because it requires a lot of energy to stop an electron from filling up its 7 electron filled valence shell.

The trends for electron affinity and electronegativity increase across a period, and increase up a group.

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