AP BIOLOGY

Detailed explanation-1: -In the case of phosphorus, 5 covalent bonds are possible-as in PCl5.

Detailed explanation-2: -A single covalent bond has two shared electrons, one contributed by each atom. Because the phosphorus atom is able to contribute three electrons, it is able to participate in three covalent bonds, whereas each hydrogen atom has only one electron to share and so can form only one bond.

Detailed explanation-3: -In a phosphorous molecule, all bonds are non-polar covalent, as all atoms are equivalent and share equal electrons. In oxygen, there is the bonding between the atoms having the same electronegativity thus, have equal sharing of electrons. Thus oxygen does not have polar covalent bonds.

Detailed explanation-4: -One way to predict the type of bond that forms between two elements is to compare the electronegativities of the elements. In general, large differences in electronegativity result in ionic bonds, while smaller differences result in covalent bonds.