Factors on which electronegativity depends

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Unknown October 3, at PM. Unknown October 20, at PM. Unknown June 13, at PM. Sarthtyagi November 24, at PM. Unknown November 28, at PM. The magnitude of electronegativity of an atom depends upon the following factors:. Copyright c Learning Top Notch. Learning Top Notch. Higher the effective nuclear charge of an atom, greater is its tendency to pull the shared pair of electrons and consequently greater is its electronegativity. Electronegativity decreases with the increase in the size of the atom.

If it increases up to fluorine, it must decrease as you go down. The chart shows the patterns of electronegativity in Groups 1 and 7. Consider sodium at the beginning of period 3 and chlorine at the end ignoring the noble gas, argon. Think of sodium chloride as if it were covalently bonded. Both sodium and chlorine have their bonding electrons in the 3-level.

The electron pair is screened from both nuclei by the 1s, 2s and 2p electrons, but the chlorine nucleus has 6 more protons in it. It is no wonder the electron pair gets dragged so far towards the chlorine that ions are formed.

Electronegativity increases across a period because the number of charges on the nucleus increases. That attracts the bonding pair of electrons more strongly. As you go down a group, electronegativity decreases because the bonding pair of electrons is increasingly distant from the attraction of the nucleus. Consider the hydrogen fluoride and hydrogen chloride molecules:. The bonding pair is shielded from the fluorine's nucleus only by the 1s 2 electrons. In the chlorine case it is shielded by all the 1s 2 2s 2 2p 6 electrons.

But fluorine has the bonding pair in the 2-level rather than the 3-level as it is in chlorine. If it is closer to the nucleus, the attraction is greater. At the beginning of periods 2 and 3 of the Periodic Table, there are several cases where an element at the top of one group has some similarities with an element in the next group. Three examples are shown in the diagram below. Notice that the similarities occur in elements which are diagonal to each other - not side-by-side. For example, boron is a non-metal with some properties rather like silicon.

Unlike the rest of Group 2, beryllium has some properties resembling aluminum. And lithium has some properties which differ from the other elements in Group 1, and in some ways resembles magnesium.

There is said to be a diagonal relationship between these elements. There are several reasons for this, but each depends on the way atomic properties like electronegativity vary around the Periodic Table.

So we will have a quick look at this with regard to electronegativity - which is probably the simplest to explain. Electronegativity increases across the Periodic Table. So, for example, the electronegativities of beryllium and boron are:.

Electronegativity falls as you go down the Periodic Table. So, for example, the electronegativities of boron and aluminum are:. Electronegativity is a property that describes the tendency of an atom to attract electrons or electron density toward itself. The higher its electronegativity, the more an element attracts electrons.

Electronegativity is not directly measured, but is instead calculated based on experimental measurements of other atomic or molecular properties. Several methods of calculation have been proposed, and although there may be small differences in the numerical values of the calculated electronegativity values, all methods show the same periodic trend among the elements.

Electronegativity, as it is usually calculated, is not strictly a property of an atom, but rather a property of an atom in a molecule. Properties of a free atom include ionization energy and electron affinity. It is expected that the electronegativity of an element will vary with its chemical environment, but it is usually considered to be a transferable property; that is to say, similar values will be valid in a variety of situations.

Where electrons are in space is a contributing factor because the more electrons an atom has, the farther from the nucleus the valence electrons will be, and as a result they will experience less positive charge; this is due to their increased distance from the nucleus, and because the other electrons in the lower-energy core orbitals will act to shield the valence electrons from the positively charged nucleus.

The most commonly used method of calculation for electronegativity was proposed by Linus Pauling. This method yields a dimensionless quantity, commonly referred to as the Pauling scale, with a range from 0. If we look at the periodic table without the inert gases, electronegativity is greatest in the upper right and lowest at the bottom left.