Chapter 9 CompoundsLesson 1 Notes

VocabularyChemical Formula – a

shorthand way to describe a compound.

Chemical Reaction – process in which one or more substances are changed into one or more DIFFERENT substances.

Combining ElementsElements join together to create

compounds.Compounds usually have different

properties from the elements that make them up. For example:

Water is created by chemically joining two gasses.

H

HO H O H

Gas GasLiquid

+

Many Compounds Are found in nature Others are created in a laboratory Some compounds are made up of just

two compounds and others are made up of several.

For example: CO2 = Carbon (C) and Oxygen (O)

CaCO3 = Calcium (Ca), Carbon (C), and Oxygen (O)

Making and Breaking Compounds To form or break a compound, a

chemical REACTION must occur. This will only happen if energy is added

(most commonly in the form of heat).

How to Read a Chemical Formula Each capital letter in a formula represents an

element on the periodic table.

H2O NaCl

The subset number tells you how many atoms of that element are in each molecule

H2O

Hydrogen Oxygen Sodium Chloride

Two hydrogen

Let’s Practice What You Know!

Let’s look that the chemical formula Fe2O3

How many atoms of Iron are there? Oxygen?

Write the chemical formula for the molecule you see here:

What do you know about the chemical formula for sodium bicarbonate NaHCO3? Think…Do I know the elements, number

of each, number of total atoms….

H O H

Everyday Compounds Water is Earth’s most abundant

element. The earth is made up of 75% water Your body is 66% water

You use compounds everyday. Here are some everyday compounds:

Everyday Compounds