Final answer:
The elements C and F, N and Br, and H and C can form covalent bonds. Li and Cl typically form an ionic bond, while Co and Cl do not typically form a covalent bond.
Step-by-step explanation:
Covalent bonds are characterized by the sharing of valence electrons between nonmetal atoms. These bonds are formed to achieve a full set of electrons in their outer shell, usually reaching an octet for most elements or a duet for hydrogen. When evaluating which combinations of elements could form a covalent bond, one primarily looks for pairs of nonmetals or a nonmetal bonding with hydrogen.
Let's assess the given combinations:
- Li and Cl: Lithium (Li) is a metal and chlorine (Cl) is a nonmetal. Normally, they form an ionic bond, not a covalent bond.
- C and F: Both carbon (C) and fluorine (F) are nonmetals with four and seven valence electrons respectively, and can form a covalent bond.
- N and Br: Nitrogen (N) and bromine (Br) are both nonmetals and can form a covalent bond.
- Co and Cl: Cobalt (Co) is a transition metal, and typically does not form covalent bonds with nonmetals like chlorine (Cl).
- H and C: Hydrogen (H) and carbon (C) are a classic covalent pairing, as seen in many organic compounds.
In summary, the combinations C and F, N and Br, and H and C are capable of forming covalent bonds.