Reading Chemical Formulas

Chemical Formulas

Have your journal out and a pencil

Multiple Select

Which of the following is a compound?

• Au

• NaCl

• O2

• P

• Ar

Multiple Select

Which of the following is a molecule?

• Au

• O2

• Potassium

• P

• Ar

​Recap!

• Compounds - Contain more than one element

• ​Element - a pure substance with one type of element

• ​Molecule - More than one of the same type of element bonded together

​Chemical formulas

• ​What are they?

  • ​A chemical formula is a description of the number and kind of atoms found in a single molecule of a substance, using the symbol for each element and a subscript number to state the number of atoms of the element to the left of the subscript.

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  • ​Or...

    • ​They tell us what elements are used

    • ​How many elements are present

    • ​They help us identify substances

​What do they look like?

Parts and Pieces...

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Subscripts​

• ​Tells us how many individual atoms there are in a chemical formula

• ​They are the smaller numbers that are behind an element

• ​INDIVIDUAL ATOMS

​Coefficients

• ​ Coefficients are the LARGER NUMBERS in front of the element/compound

• ​They tell us how many compounds or elements there are in a chemical formula

​There is some math involved....

• ​ The only math you will be doing is multiplication and some addition

• ​I recommend having a calculator out if needed

• ​How do we find the total number of atoms?

How to find the total number of atoms

• First, pick an element Let's start with Nitrogen (N)

Multiple Choice

How many Nitrogen atoms are there?

• 4

• 8

• 2

​Cool! But what about Hydrogen?

• ​Both Hydrogen atoms have a Coefficient and a Subscript

• ​Any ideas???

​Cool! But what about Hydrogen?

• ​Both Hydrogen atoms have a Coefficient and a Subscript

• ​Any ideas???

• ​You multiply the Subscript with the Coefficient

Multiple Choice

How many total Hydrogen (H) atoms are there?

• 2

• 5

• 12

• 10

​One last thing... Which side is which???

​Reactants are ALWAYS on the LEFT side of the arrow

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​Products are ALWAYS on the RIGHT side of the arrow

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​Reactants react to produce products!

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