Question

ionic bonds, such as in sodium chloride, ______
are bonds created by the gaining of electrons
share electrons
are formed by the association of ions with the same charge
are formed by the association of ions with opposite charge

Explanation:

1. Recall the definition of ionic bonds: Ionic bonds are formed between a metal (like Na) and a non - metal (like Cl) when one atom transfers electrons to another. Sodium (Na) loses an electron to become a positively charged ion ($Na^+$), and chlorine (Cl) gains that electron to become a negatively charged ion ($Cl^-$).
2. Analyze the options:

• Option "are bonds created by the gaining of electrons": Ionic bonds involve both loss and gain of electrons (Na loses, Cl gains), so this is incorrect.
• Option "share electrons": Sharing of electrons is characteristic of covalent bonds, not ionic bonds, so this is incorrect.
• Option "are formed by the association of ions with the same charge": Ions with the same charge repel each other, so they can't form a bond.
• Option "are formed by the association of ions with opposite charge": Positively charged ions (cations) and negatively charged ions (anions) are attracted to each other, and this electrostatic attraction forms an ionic bond. For example, in NaCl, $Na^+$ (positive) and $Cl^-$ (negative) are held together by ionic bonding.

Answer:

are formed by the association of ions with opposite charge