Question

why is it that oxygen is less than electronegative than hydrogen??? Can someone please explain it to me how to find electronegativity and why hydrogen is electronegative than oxygen?

Answer 1

Electronegativity, symbol χ (the Greek letter chi), is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself and thus the tendency to form negative ions.

Water is 2 hydrogen atoms covalently bonded to the oxygen atom, which in other words is just the sharing of a pair of electrons between them. However, the electronegativity of oxygen is greater than the electronegativity of hydrogen atom, so oxygen attracts the electrons closer towards itself, though not completely, resulting in a partial negative charge on the oxygen and partial positive charge on the hydrogen. So there is a dipole along the H-O bond, which makes it polar.

Also, O is not magnetically attracted to H. In covalent bonding, due to the sharing of electrons, while each atom wants to complete it's stable outer structure (8 electrons for O, 2 for Hydrogen), it is also "unwilling" to give up the electron completely due to the strong electrostatic attraction between the positive nucleus and the negative electron.

Read more: http://www.physicsforums.com

Answer 2

oxygen is NOT less electronegative than hydrogen is.

Answer 3

Actually, water is more electronegative than hydrogen. It has a higher tendency to pull the hydrogen bonds towards itself. Think of a water molecule: The oxygen atom in the middle attracts both the hydrogens on either ends.

Answer 4

that's not the question.

Answer 5

Well, theres always the fact that oxygen is closer to stabilizing the number of electrons it can hold in its shell, right?

Whereas Hydrogen is less stable, and tends to lose them.

Answer 6

the question itself is incorrect. the question states why is oxygen less electrnegative than hydrogen, when in fact it is not.

Answer 7

Thank you guys for answering... I know that oxygen is less electronegative than hydrogen but when there was a question on my homework that told me to draw Lewis structure for H2O, and the central atom had to be the least electronegative atom, but the central atom was considered as O, when H is much less electronegative than O...

Answer 8

ELECTRONEGATIVITY:

When you're talking about ELECTRONEGATIVITY, it is ALWAYS in reference to a COVALENT BOND

A COVALENT BOND IS A SHARED PAIR OF ELECTRONS

In Water, it can be represented like this:

H--:--O--:--H

As you can see, the COVALENT BOND (:) is THE SAME LENGTH AWAY FROM EACH ATOM

Hower, it doesn't actually work like this.

ELECTRONEGATIVITY IS THE TENDANCY OF ATOMS TO PULL BONDING ELECTRONS TOWARDS THEMSELVES

This 'tendancy' can occur for a NUMBER OF REASONS, including

- an atom having a MORE POSITIVE NUCLEUS (Therefore, attraction to NEGATIVE ELECTRONS is STRONGER)
- an atom having LESS SHELLS (therefore, POSITIVE NUCLEUS is closer to NEGATIVE ELECTRONS, causing MORE ATTRACTION)

OXYGEN is MORE ELECTRONEGATIVE than HYDROGEN

For this reason, the bonding in water looks more like THIS:

H---:-O-:---H

As you can see, the electrons are CLOSER to the OXYGEN

The MORE ELECTRONEGATIVE OXYGEN has a HIGHER TENDANCY to pull bonding electrons towards itself.

---------------------------------
POLARITY:

Electronegativity gives rise to an important property of BONDS.

Remember that ELECTRONS ARE NEGATIVE

H---:-O-:---H

As we established before, Oxygen is more electronegative that Hydrogen

- It pulls NEGATIVE ELECTRONS closer to itself

- Normally, when directly in the middle, the overall charge of atoms on either side of the bond is NEUTRAL

- The NEGATIVE ELECTRONS influence the OXYGEN giving it a PARTIAL NEGATIVE CHARGE (represented as (Delta) -ve)

- The NEGATIVE electrons are further away from the H atoms. They obtain a PARTIAL POSITIVE CHARGE (represented as (Delta) +ve)

It is important to remember that these charges are only PARTIAL (not a FULL negative or positive)

If they were FULL charges, they would be IONS.

-------------------------------

Hydrogen Bonding

When a bond becomes POLAR, (Delta) -ve charges ATTRACT (Delta) +ve charges

This gives rise to HYDROGEN BONDING

A HYDROGEN BOND is 1/10th the strength of a COVALENT BOND, and gives water some of it's most important properties

- Surface cohesion
- High density (higher than iron!)

Answer 9

And you did not cite that this was a yahoo answer, but took it as your own, @Mvpriest6