Ionic Compounds and Their Formulas

This video tutorial covers the basics of stoichiometry, focusing on chemical formulas, valency, and ionic compounds. It explains how to determine molecular and empirical formulas, the concept of valency, and how to balance ionic compounds. The tutorial also introduces the crisscross method for finding the simplest ratio of ions in a compound, using examples like potassium chloride and boron oxide.

What is the correct representation for a compound with one sodium atom and one chlorine atom?

• NaCl2

• Na2Cl2

• Na2Cl

• NaCl

Which of the following is an example of a molecular formula?

• All of the above

• H2O

• C2H5O

• CH4

How do you find the empirical formula from a molecular formula?

• Multiply all subscripts by their highest common factor

• Divide all subscripts by their lowest common denominator

• Subtract the smallest subscript from the largest

• Add all subscripts together

What does valency indicate about an atom?

• The atomic mass of the atom

• The number of bonds an atom can form

• The number of neutrons in the atom

• The number of protons in the atom

Which group of elements typically loses electrons to form stable ions?

• Group 1 to 3 metals

• Group 4 elements

• Group 5 to 7 non-metals

• Noble gases

What is the charge of a sodium ion?

• -2

• -1

• +1

• +2

In an ionic compound, what must the total charge be?

• Zero

• Negative

• Equal to the number of ions

• Positive

What is the formula for potassium chloride?

• KCl

• K2Cl

• KCl2

• K2Cl2

How is the crisscross method used in determining ionic compound formulas?

• By multiplying the charges of the ions

• By adding the charges of the ions

• By subtracting the charges of the ions

• By crisscrossing the charges to find the simplest ratio

When using the crisscross method, when should you enclose a compound ion in brackets?

• When the ion has a positive charge

• When more than one of that ion is needed

• When the ion is used only once

• When the ion has a negative charge