Question 1

What is electronegativity?

Accepted Answer

Electronegativity is the tendency of an atom in a molecule to attract the shared electron pair toward itself. A greater difference between two bonded atoms generally gives a more polar bond and a greater tendency toward ionic character.

Question 2

Why is the H-H bond non-polar covalent?

Accepted Answer

Hydrogen has a Pauling electronegativity value of 2.1 on both atoms, so the difference is 0.0. Their shared electron density is symmetric and the bond has no bond dipole.

Question 3

Why are the atoms in H-F partially charged?

Accepted Answer

Fluorine has a Pauling value of 4.0, compared with hydrogen at 2.1. Fluorine therefore attracts the shared electron density more strongly, giving H a partial positive charge and F a partial negative charge; H-F remains described as polar covalent with high ionic tendency.

Question 4

How do the bond characters of C-O, C-S, H-F and H-Cl compare?

Accepted Answer

Their electronegativity differences are 1.0, 0.0, 1.9 and 0.9 respectively. C-S is non-polar because C and S both have a value of 2.5; the other three are polar covalent, with H-F showing the greatest ionic tendency.

Question 5

Why are H2O and H2S polar despite having two identical bonds?

Accepted Answer

Both molecules are bent, and each central atom has two lone pairs. The two bond dipoles do not cancel in this geometry, so the molecules have a net dipole; H2O has a bond angle of 104.5 degrees and H2S approximately 92 degrees.

Electronegativity & Bond Character — Pulling the Electron Cloud

About this lab

Practice