Electronegativity facts for kids

Electronegativity, shown by the symbol χ, is a special chemical property that tells us how strongly an atom can pull electrons towards itself. Think of it like a magnet for electrons!

An atom's electronegativity is affected by two main things:

• Its atomic number (how many protons it has).
• The distance between its outermost electrons (called valence electrons) and its center (the nucleus). These outermost electrons are the ones involved in chemical bonding.

A famous scientist named Linus Pauling first came up with the idea of electronegativity in 1932. He used it to help explain how atoms connect to each other. Generally, electronegativity follows a pattern on the periodic table. It usually increases as you go from the bottom-left to the upper-right. This is known as a periodic trend.

The most common way to measure electronegativity is using the Pauling scale. This scale gives atoms a number, usually between 0.7 and 3.98. For example, hydrogen has a value of 2.20 on this scale. These numbers don't have a unit, they are just values to compare atoms.

The opposite of electronegativity is electropositivity. This measures how easily an atom gives away its electrons.

What is the Pauling Scale?

Linus Pauling created the idea of electronegativity to explain why some chemical bonds are stronger than others. He noticed that a bond between two different atoms (like A-B) was often stronger than the average strength of bonds between two of the same atoms (like A-A and B-B). Pauling believed this extra strength came from how much one atom pulled electrons from the other.

To create his scale, Pauling needed a starting point. He chose hydrogen because it forms bonds with many different elements. Hydrogen's electronegativity was first set at 2.1, but it was later changed to 2.20.

To figure out which atom was more electronegative, scientists often used what they already knew about chemicals. For example, when hydrogen bromide (H-Br) dissolves in water, it splits into H⁺ and Br^-. This showed that bromine pulled the electrons more strongly than hydrogen, making bromine more electronegative.

Today, we often use "revised Pauling" electronegativity values. These values include more up-to-date information about the energy involved in chemical reactions.

Images for kids

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  Electrostatic potential map of a water molecule, where the oxygen atom has a more negative charge (red) than the positive (blue) hydrogen atoms

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  This chart shows how Mulliken electronegativity values compare to Pauling electronegativity values.

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  This chart shows how Sanderson electronegativity values compare to Pauling electronegativity values.

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  This chart shows how Allen electronegativity values compare to Pauling electronegativity values.

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  This graph shows how the electronegativity of certain atoms affects a measurement called "isomer shift" in tin compounds.

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  This chart shows how Pauling electronegativity changes as you go down different groups in the periodic table.

See also

In Spanish: Electronegatividad para niños