Answer to Question #204790 in General Chemistry for Master j

Question

i. State THREE (3) properties of covalent compounds.

ii. Draw the Lewis structure for the molecule of ammonia (NH₃).

iii. State the geometry of, and the bond angles in, the ammonia (NH₃) molecule.

iv. PH₃ has the same geometry as NH₃, however, the bond angle in PH₃ is less than that in NH₃. Provide an explanation for this observation. 

Answer 1

I) Low boiling points and melting points.

Various colors.

Poor conductors of heat and electricity.

ii)

iii) In the ammonia molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of NH 3 is called trigonal pyramidal (see Figure 9). Recall that the bond angle in the tetrahedral CH 4 molecule is 109.5°.

iv) The bond angle in NH3​ is larger than, in PH3​ because the P−H bonds are longer and the lower electronegativity of P permits electron-density to be displaced towards hydrogen to a greater extent than in the case of NH3.