Question

a. ionic compounds have low melting points; covalent compounds have high melting points
b. ionic compounds conduct electricity when dissolved; covalent compounds usually do not
c. ionic compounds are made of nonmetals only; covalent compounds are made of metals and nonmetals
d. ionic compounds share electrons; covalent compounds transfer electrons
q7. why does fluorine (f) form an anion?
a. it loses electrons to become stable
b. it gains one electron to complete its octet
c. it has a full outer shell naturally
d. it shares four electrons with another atom
q8. what is the correct formula for a compound of aluminum and nitrogen?
a. aln
b. al₂n
c. aln₂
d. al₂n₃
q9. what is the correct formula for dinitrogen tetroxide?
a. no₂
b. n₂o₄
c. no₄
d. n₂o
dok 3 - strategic thinking
q10. why do noble gases usually not form compounds?
a. they are metals and unstable
b. they have full outer electron shells
c. they prefer ionic bonds only
d. they contain no protons
q11. a student says nacl is covalent. which is the best evaluation?
a. correct, because na and cl share electrons
b. incorrect, because nacl is ionic (metal + nonmetal)
c. correct, because nacl has weak bonds
d. incorrect, because nacl is a mixture
q12. why is mgf₂ the correct formula for magnesium fluoride?

Explanation:

• Q6: Ionic compounds conduct electricity when dissolved due to the presence of ions that can move freely. Covalent compounds usually do not as they consist of neutral molecules.
• Q7: Fluorine has 7 valence electrons and gains one electron to complete its octet and form an anion.
• Q8: Aluminum has a +3 charge and nitrogen has a -3 charge, so the formula is AlN to balance charges.
• Q9: Dinitrogen tetroxide has 2 nitrogen atoms and 4 oxygen atoms, so the formula is N₂O₄.
• Q10: Noble gases have full outer electron shells, making them stable and less likely to form compounds.
• Q11: NaCl is an ionic compound as it is formed between a metal (Na) and a non - metal (Cl) through electron transfer.
• Q12: Magnesium has a +2 charge and fluorine has a -1 charge. To balance charges, 2 fluorine atoms are needed for each magnesium atom, giving the formula MgF₂.

Answer:

• Q6: B. Ionic compounds conduct electricity when dissolved; covalent compounds usually do not
• Q7: B. It gains one electron to complete its octet
• Q8: A. AlN
• Q9: B. N₂O₄
• Q10: B. They have full outer electron shells
• Q11: B. Incorrect, because NaCl is ionic (metal + nonmetal)
• Q12: Magnesium has a +2 charge and fluorine has a -1 charge. Two fluorine atoms are needed to balance the +2 charge of one magnesium atom.