Counting Atoms in Chemical Formulas

This video tutorial introduces the concept of counting atoms in chemical formulas, starting with simple compounds and progressing to more complex ones involving parentheses. The instructor explains how to identify elements using capital letters and subscripts, and how to handle compounds with multiple atoms and parentheses. The video includes practice problems to reinforce the concepts taught.

Why is it important to learn how to count atoms in chemical formulas?

• To understand the periodic table

• To keep track of the number of atoms in compounds

• To memorize chemical symbols

• To calculate molecular weight

In a chemical formula, what does a capital letter signify?

• The end of a formula

• A lowercase letter follows

• A new element

• The start of a new molecule

How do you determine the number of atoms for an element with a subscript in a chemical formula?

• Multiply the subscript by two

• Ignore the subscript

• Add one to the subscript

• The subscript indicates the number of atoms

What does a subscript of '1' imply in a chemical formula?

• There is no atom of that element

• There is one atom of that element

• The element is not present

• The element is doubled

In a formula with parentheses, what does a number outside the parentheses indicate?

• The number of molecules

• The number of atoms inside the parentheses is multiplied by this number

• The number of elements inside the parentheses

• The number of compounds

How many total atoms are in the formula Ba3(PO4)2?

• 15

• 10

• 12

• 13

What is the total number of atoms in H2O?

• 2

• 3

• 4

• 5

In the formula H2SO4, how many oxygen atoms are present?

• 5

• 4

• 3

• 2

How many total atoms are in the formula Cu(NO3)2?

• 8

• 9

• 11

• 10

What is the first step in counting atoms in a complex formula?

• Count the total number of elements

• Identify the elements and their subscripts

• Add all subscripts together

• Multiply all numbers by two