Question

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Explanation:

1. Covalent bonds involve sharing of valence electrons in paired form, with electrons belonging to both atoms involved in the bond.
2. Covalent bonds form between nonmetal atoms, following the octet rule (8 valence electrons for stability) for most elements; hydrogen only needs 2 valence electrons, following the duet rule, as its first energy level holds a maximum of 2 electrons.
3. Carbon has 4 valence electrons, each hydrogen has 1; they share electrons to form 4 single bonds, with carbon having 8 valence electrons and each hydrogen having 2.
4. Carbon has 4 valence electrons, each oxygen has 6; carbon forms double bonds with each oxygen, giving all atoms 8 valence electrons.
5. Phosphorus has 5 valence electrons, each chlorine has 7; phosphorus forms 3 single bonds with chlorine atoms, keeping 1 lone pair, and each chlorine has 3 lone pairs, satisfying the octet rule for all atoms.
6. Hydrogen has 1 valence electron, chlorine has 7; they form a single bond, giving hydrogen 2 valence electrons and chlorine 8.
7. Carbon has 4 valence electrons, hydrogen has 1 each, oxygen has 6; carbon forms single bonds with two hydrogens and a double bond with oxygen, giving all atoms full valence shells (carbon/oxygen have 8, hydrogens have 2).

Answer:

1. valence; electron pairs; both bonded atoms
2. nonmetals; nonmetals; Octet; 8; Duet
3. (Lewis structure provided as example, complete with lone pairs:

    H
    ··
H··C··H
    ··
    H

)

1. (Complete Lewis structure with lone pairs:

:O::C::O:

)

1. (Complete Lewis structure with lone pairs:

      ..
Cl: P :Cl
      ..
      |
      Cl:
         ..

)

1. (Complete Lewis structure with lone pairs:

H:Cl:
   ..

)

1. (Complete Lewis structure with lone pairs:

    H
    |
H-C=O
    :

)