Why is water, ammonia and hydrogen sulfide polar?

Question

thank you !!

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Answer 1

By getting their electronegativity difference. You can get the elements electronegativity in the periodic table of elements. If electronegativity difference is lesser than the range of 1.7-1.9 it is polar.And if its 0 its nonpolar. And if If electronegativity difference(ED) is greater than the range of 1.7-1.9 its an ionic bond.For example in water(H2O). H has 2.1 electronegativity and O has 3.5. So ED= 3.5-2.1=1.4 so its polar. Then NH4(ammonia) N has 3.0 and H has 2.1, so ED=3.0-2.1=.9 its also polar. And H2S(Hydrogen sulfide) H has 2.1 and sulfur has 2.5, so ED=2.5-2.1=.4 so its also polar.

Answer 2

that is easy because

water: the presence of oxygen of high electronegativity and hydrogen of 2.1 electronegativity so the electrons in the covalent bond are more attracted to the oxygen atom thus a partial negative is given to the oxygen and a parial positive is given to the hydrogen.

as for ammonia and hydrogen sulphide

it is the same reason as Nitrogen and sulpher has higher electronegativities than the hydrogen

Answer 3

General Rule

Look at the molecular shape of the compound.

If for example like in CH4 molecular diagram

All the electrons are spread equally over the molecule it is classified as non polar.

If however it appears like Water molecular diagram

The majority of the electrons are clustered at the oxygen atom the molecule is classified as polar, the oxygen being the negative pole and the hydrogens are positive poles.

Electron dot Diagrams also show this clearly