Cross-Over Method for Chemical Formulas

What is the first step in the cross-over method for writing chemical formulas?

• Write the formula with charges included.

• Write the ions with their charges.

• Simplify the subscripts.

• Cross over the charges.

What does the cross-over step in the method involve?

• Adding the charges of the ions.

• Subtracting the charges of the ions.

• Using the charge of one ion as the subscript for the other ion.

• Multiplying the charges of the ions.

What is the correct formula for sodium chloride (Na⁺ and Cl⁻)?

• Na₂Cl

• NaCl

• NaCl₂

• Na₂Cl₂

What is the formula for magnesium oxide (Mg²⁺ and O²⁻)?

• Mg₂O₂

• MgO₂

• MgO

• Mg₂O

How would you write the formula for calcium nitrate (Ca²⁺ and NO₃⁻)?

• CaNO₃

• Ca₂(NO₃)₂

• Ca(NO₃)₂

• Ca₂NO₃

What is the correct formula for aluminum oxide (Al³⁺ and O²⁻)?

• Al₂O₃

• AlO₂

• Al₃O

• Al₃O₂

What is the formula for potassium fluoride (K⁺ and F⁻)?

• KF₂

• KF

• K₂F

• K₂F₂

What is the simplified formula for magnesium chloride (Mg²⁺ and Cl⁻)?

• MgCl

• Mg₂Cl₂

• MgCl₂

• Mg₃Cl

What is the simplified formula for barium fluoride (Ba²⁺ and F⁻)?

• BaF₂

• Ba₂F₂

• BaF

• Ba₂F

If the cross-over method gives the formula Al₂O₃, what were the original charges on the ions?

• Al²⁺ and O³⁻

• Al³⁺ and O²⁻

• Al⁺ and O²⁻

• Al³⁺ and O⁻