Question

decide whether each pair of elements in the table below will form an ionic compound.

element #1	element #2	forms ionic compound?	empirical formula of ionic compound
sodium	fluorine	yes no
sulfur	chlorine	yes no
bromine	barium	yes no

Explanation:

Step1: Recall ionic - compound formation rule

Ionic compounds form between a metal and a non - metal.

Step2: Analyze strontium and lithium pair

Both strontium (Sr) and lithium (Li) are metals. So they do not form an ionic compound.

Step3: Analyze sodium and fluorine pair

Sodium (Na) is a metal and fluorine (F) is a non - metal. They form an ionic compound. Sodium forms a + 1 ion ($Na^+$) and fluorine forms a - 1 ion ($F^-$), so the empirical formula is $NaF$.

Step4: Analyze sulfur and chlorine pair

Both sulfur (S) and chlorine (Cl) are non - metals. They do not form an ionic compound.

Step5: Analyze bromine and barium pair

Barium (Ba) is a metal and bromine (Br) is a non - metal. They form an ionic compound. Barium forms a + 2 ion ($Ba^{2 + }$) and bromine forms a - 1 ion ($Br^-$), so the empirical formula is $BaBr_2$.

Answer:

strontium and lithium: no,
sodium and fluorine: yes, $NaF$
sulfur and chlorine: no,
bromine and barium: yes, $BaBr_2$