Why is nitrogen more electronegative than bromine?
回答 (1)
2018-02-21 1:33 pm
Electronegativity is a measure of the ability of an atom to attract bond-pair electrons. Two counter factors affect the electronegativity.
The first factor is the size of atom. For a smaller atom, the bond-pair electrons are closer to nucleus leading to a stronger nuclear attraction. Nitrogen atom is smaller than bromine atom because nitrogen atom has a smaller number of electron shells. According to this factor, nitrogen is more electronegative than bromine.
The second factor is the effective nuclear charge (NOT only nuclear charge). The greater the nuclear charge, the stronger the attractive force between the bond-pair electrons and the nucleus is, and thus higher electronegative. The effective nuclear charge of nitrogen atom (N: 2, 5) is +5 as it has 7 protons in its nucleus and 2 inner shell electrons, while the effective nuclear charge of bromine atom (Br: 2, 8, 18, 7) is +7 as it has 35 protons in its nucleus and 28 inner shell electrons. According to this factor, bromine is more electronegative than nitrogen.
For nitrogen and bromine, the first factor outweighs the second factor. Therefore, nitrogen is more electronegative than bromine.
The first factor is the size of atom. For a smaller atom, the bond-pair electrons are closer to nucleus leading to a stronger nuclear attraction. Nitrogen atom is smaller than bromine atom because nitrogen atom has a smaller number of electron shells. According to this factor, nitrogen is more electronegative than bromine.
The second factor is the effective nuclear charge (NOT only nuclear charge). The greater the nuclear charge, the stronger the attractive force between the bond-pair electrons and the nucleus is, and thus higher electronegative. The effective nuclear charge of nitrogen atom (N: 2, 5) is +5 as it has 7 protons in its nucleus and 2 inner shell electrons, while the effective nuclear charge of bromine atom (Br: 2, 8, 18, 7) is +7 as it has 35 protons in its nucleus and 28 inner shell electrons. According to this factor, bromine is more electronegative than nitrogen.
For nitrogen and bromine, the first factor outweighs the second factor. Therefore, nitrogen is more electronegative than bromine.
2018-02-21 11:34 am
Electronegativity.....
To two significant digits, they are the same. Nitrogen is 3.04, while bromine is 2.96. Hardly enough difference to worry about. A bond between nitrogen and bromine will be essentially nonpolar.
What is electronegativity? It is an average measure of the ability of an element to attract shared pairs of electrons. Since the outermost electrons for nitrogen are closer to the nucleus we could surmise that nitrogen would have a slight edge. But bromine is many more protons and therefore, a substantial attraction for electrons. And as you can see they just about attract shared pairs of electrons equally. Also remember, that the electronegativity is an average and it can vary with the environment of the atom, meaning that the element with which it bonds and the apparent oxidation state can change the electronegativity.
To two significant digits, they are the same. Nitrogen is 3.04, while bromine is 2.96. Hardly enough difference to worry about. A bond between nitrogen and bromine will be essentially nonpolar.
What is electronegativity? It is an average measure of the ability of an element to attract shared pairs of electrons. Since the outermost electrons for nitrogen are closer to the nucleus we could surmise that nitrogen would have a slight edge. But bromine is many more protons and therefore, a substantial attraction for electrons. And as you can see they just about attract shared pairs of electrons equally. Also remember, that the electronegativity is an average and it can vary with the environment of the atom, meaning that the element with which it bonds and the apparent oxidation state can change the electronegativity.
收錄日期: 2021-05-01 14:17:32
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