Chapter U2.43, Problem 7E

Interpretation Introduction

Interpretation : The reason for some molecules to be attracted to a charged wand is to be explained using electronegativity.

Concept Introduction :

The tendency of an atom to attract shared electrons is called electronegativity. Atom with higher electronegativity attracts more electrons than atom with low electronegativity.

Answer to Problem 7E

A polar molecule is a molecule that possesses partial charges on its atoms. There is a partial positive and a partial negative charge on atoms. This is due to the difference in electronegativity of atoms forming the bond.Atoms that are more electronegative have partial negative charge and atoms that are less electronegative have positive charge. This results in formation of a polar bond.

Polar molecules are attracted by a charged wand.

Explanation of Solution

A molecule is polar due to the difference in electronegativity of atoms forming the bond which causes difference in sharing of electrons. One atom that is more electronegative attracts the shared electrons more strongly than the other atom. Because of this, displacement of electrons of one atom develops a partial negative charge and other atom develops a partial positive charge. The result is a polar molecule.

When a charged wand is brought near a polar liquid like water, it attracts the stream of water. This is due to polarity in water molecules. The water molecules have slight negative charge on oxygen atom and slight positive charge on hydrogen atoms as oxygen is more electronegative than hydrogen. Due to this the hydrogen atoms orient themselves towards the negatively charged wand and the whole stream of water gets attracted towards the wand.

Some liquids are polarin nature such as water, vinegar, rubbing alcohol etc. These are attracted by the charged wand.

Conclusion

The tendency of an atom to attract shared electrons is called electronegativity. Difference in electronegativity of atoms results in formation of a polar bond. This causes polar molecules to get attracted towards a charged wand.