Criss Cross Rule

Open Ended

How does the concept of charge relate to the formation of ionic compounds?

Multiple Choice

Why is understanding oxidation states important in the study of ionic compounds?

• Because it helps predict how atoms will bond and form compounds

• Because it determines the color of the compound

• Because it tells us the melting point of the compound

• Because it shows the physical state of the compound

Multiple Choice

What does the oxidation state of an atom indicate?

• The number of protons in the atom

• The charge the atom has due to a loss or gain of electrons

• The number of neutrons in the atom

• The atomic mass of the atom

Multiple Choice

If an atom has a charge of -2, what does this tell you about its electrons?

• It lost two electrons

• It gained two electrons

• It lost two protons

• It gained two protons

Open Ended

Explain why knowing the number of electrons lost or gained by an atom can help you avoid drawing an extensive Lewis Structure.

Multiple Select

Which of the following statements about ionic crystal lattices are correct?

• They look like a 3D checkerboard

• They are formed by covalent bonds

• Reducing subscripts shows the smallest unit of the lattice

• They are made up of repeating units

Multiple Choice

In the reaction between magnesium (Mg) and oxygen (O), what is the oxidation state of oxygen after it gains two electrons from magnesium?

• +2

• -2

• 0

• +1

Multiple Choice

What is the correct chemical formula for the compound formed between magnesium (Mg) and oxygen (O)?

• MgO

• MgO2

• Mg2O2

• Mg2O

Multiple Select

Which of the following formulas are correctly reduced according to the criss-cross method?

• BaBr2

• Al4C3

• Na2O

• Mg2O2

Open Ended

Explain the criss-cross method for writing chemical formulas using examples from the provided answers.

Open Ended

How does understanding oxidation states help you predict the formulas of ionic compounds?

Open Ended

Draw the ionic Lewis Structure for Mg bonding to Cl. Is there a shortcut way to do it?