Counting Atoms

In the equation, 2Mg + O₂ ---> 2MgO, which are the reactants?

• Mg and O

• Mg and MgO

• MgO

• O and MgO

In a chemical equation elements or compounds that are produced and are located the right side are called...

• reactants

• products

What is the little number after an element in a chemical equation called?

Example: H₂

• Coefficient

• Atom

• Subscript

• Equation

The following tells us the number of molecules that are present in an equation.

• coefficient

• subscripts

• elements

How many Nitrogen (N) atoms are in 4NH₃?

• 4

• 1

• 3

• 12

How many Hydrogen (H) atoms are in 4NH₃?

• 4

• 1

• 3

• 12

How many total molecules is 4NH₃?

• 4

• 1

• 3

• 12

In the equation shown, what are the reactant(s)?

• N₂ + H₂

• NH₃

In the equation shown, what are the product(s)?

• N₂ + H₂

• NH₃

Which of the following is a chemical reaction?

• Sodium and chlorine atoms bond to form salt molecules.

• Ice melts to form water.

• Carbon dioxide freezes to form dry ice.

• Salt and water mix to form salt water.