Question

which of the following could not form an ionic compound? check all that apply. li⁺ and cl⁻ f⁻ and o²⁻ ba²⁺ and ag⁺ mg²⁺ and s²⁻

Explanation:

To determine which pairs cannot form an ionic compound, we analyze each pair by checking if the total positive charge equals the total negative charge (for charge balance) and if they are a metal - nonmetal or polyatomic ion combination (ionic compounds typically form between metals and nonmetals or polyatomic ions).

Step 1: Analyze $\boldsymbol{\ce{Li+}}$ and $\boldsymbol{\ce{Cl-}}$

The charge of $\ce{Li+}$ is $ + 1$ and the charge of $\ce{Cl-}$ is $- 1$. The sum of positive and negative charges: $+1+( - 1)=0$. Lithium ($\ce{Li}$) is a metal and chlorine ($\ce{Cl}$) is a non - metal. So, they can form the ionic compound $\ce{LiCl}$.

Step 2: Analyze $\boldsymbol{\ce{F-}}$ and $\boldsymbol{\ce{O^{2-}}}$

Both $\ce{F-}$ and $\ce{O^{2-}}$ are anions (negative ions). Ionic compounds are formed by the combination of cations (positive ions) and anions. Since there are no cations present in this pair, they cannot form an ionic compound.

Step 3: Analyze $\boldsymbol{\ce{Ba^{2+}}}$ and $\boldsymbol{\ce{Ag+}}$

Both $\ce{Ba^{2+}}$ and $\ce{Ag+}$ are cations (positive ions). For an ionic compound to form, we need a combination of positive and negative ions. Since there are no anions here, they cannot form an ionic compound.

Step 4: Analyze $\boldsymbol{\ce{Mg^{2+}}}$ and $\boldsymbol{\ce{S^{2-}}}$

The charge of $\ce{Mg^{2+}}$ is $ + 2$ and the charge of $\ce{S^{2-}}$ is $- 2$. The sum of charges: $+2+( - 2)=0$. Magnesium ($\ce{Mg}$) is a metal and sulfur ($\ce{S}$) is a non - metal. So, they can form the ionic compound $\ce{MgS}$.

Answer:

The pairs that could NOT form an ionic compound are $\ce{F-}$ and $\ce{O^{2-}}$, $\ce{Ba^{2+}}$ and $\ce{Ag+}$.