Question

multiple choice 1 point
which pair forms an ionic compound?
two metals
two nonmetals
a metal and a nonmetal
two noble gases

Explanation:

Step1: Recall ionic compound formation

Ionic compounds are formed when a metal donates electrons and a non - metal accepts electrons.

Step2: Analyze each option

• Two metals: Metals tend to lose electrons. If two metals combine, there is no significant electron transfer in the way required for ionic bond formation (they would likely form metallic bonds or alloys in some cases).
• Two nonmetals: Nonmetals usually gain electrons. When two nonmetals combine, they share electrons to form covalent bonds (e.g., \(H_2O\), \(CO_2\) are covalent compounds).
• Two noble gases: Noble gases have a full valence shell and are very unreactive. They do not form compounds easily (by ionic or covalent means in most cases).
• A metal and a nonmetal: A metal can lose electrons to form a cation and a non - metal can gain those electrons to form an anion. The electrostatic attraction between the cation and anion forms an ionic bond. For example, in \(NaCl\), \(Na\) (a metal) loses an electron to form \(Na^{+}\) and \(Cl\) (a non - metal) gains an electron to form \(Cl^{-}\), and the ionic compound \(NaCl\) is formed.

Answer:

A metal and a nonmetal.