Predicting Chemical Formulas with the Criss Cross Method

This video tutorial introduces the crisscross rule in chemistry, explaining how it helps determine chemical formulas for binary ionic compounds. The instructor discusses oxidation states, electron exchange, and provides examples using elements like magnesium, oxygen, lithium, and others. The tutorial emphasizes the importance of reducing subscripts to find the smallest unit of a crystal lattice and encourages students to practice the crisscross rule to understand chemical bonding better.

What is the oxidation state of an atom that has lost two electrons?

• Positive two

• Positive one

• Negative two

• Negative one

Tags

NGSS.HS-PS1-1

What does a positive charge on an atom indicate?

• Loss of negative electrons

• Loss of positive protons

• Gain of positive protons

• Gain of negative electrons

What is the correct chemical formula for magnesium oxide using the crisscross rule?

• Mg2O

• Mg2O2

• MgO

• MgO2

How many valence electrons does magnesium have?

• One

• Two

• Three

• Four

Tags

NGSS.HS-PS1-1

What is the chemical formula for lithium oxide using the crisscross rule?

• LiO2

• Li2O

• LiO

• Li2O2

What charge does aluminum typically take on?

• Plus three

• Plus one

• Plus two

• Minus three

What is the reduced chemical formula for aluminum nitride?

• Al3N

• Al2N3

• AlN

• Al3N3

What is the chemical formula for calcium fluoride using the crisscross rule?

• Ca2F2

• CaF2

• Ca2F

• CaF

What is the charge on fluorine when it gains one electron?

• Plus one

• Minus one

• Plus two

• Minus two

Tags

NGSS.HS-PS1-1

What is the purpose of 'training wheels' in writing chemical formulas?

• To ensure the formula is incorrect

• To make the formula look more complex

• To add extra elements to the formula

• To help beginners understand the process