Standard:
Chemical Reactions 9.3 Classify common substances as elements or compounds based on their symbols
or formulas
Chemical Reactions 9.4 Differentiate between a mixture and a compound.
Student Friendly Language: I can… classify substances as mixtures, compounds, and elements.
Elements: Elements are pure substances. What this mean is that they are the most basic form of any
substance: they cannot be broken down any further. All elements can be found on the periodic table by
themselves. When looking at the chemical formula, all elements have one capital letter, which represents
one element. Examples: O2, Na, K, Au, Ag
Compounds: Compounds are substances that are two or more elements chemically bonded together. The
only way to separate a compound is through a chemical reaction. When looking at a chemical formula,
compounds have two or more capital letters, which represent two or more elements bonded together.
Examples: H2O (water), NaCl (salt), sugar,
Mixtures: Mixtures exist of more than one pure substance mixed together. The different substances in a
mixture can be physical separated. Because mixtures are multiple substances, they do not have a
chemical formula. Examples: Salt water, air, a salad, sand (salt, calcium carbonate, quartz), acids and
bases.
elements
One type of atom
compounds
more than one
type of atom
bonded together
more than one
substance
Seperate by
physical means
Pure Substances
Matter
Mixtures
Practice:
Label the following as an element, mixture, or compound
Carbon (C)
Carbon
Dioxide
(CO2)
Salt (NaCl)
Oxygen (O2)
Air
(atmosphere)
Coca-Cola
Salt Water
Kool-Aid
Ethanol
(C2H6O)
Baking Soda
(NaHCO3)
Methane
(CH4)
Nitrogen
(N2)
Sulfur (S)
Sulfate
(SO4)
Hydrogen
(H2)
Glucose
(C6H1206)
Answer the following questions:
1. Calcium Carbonate (CaCO3) is considered a compound because it is made up of two or more:
a. Molecules
c. Gases
b. Elements
d. Solids
2. What type of matter can be separated by physical means?
a. Atom
c. Compound
b. Element
d. Mixture
3. Which of the following is a pure substance:
a. Iron (Fe)
b. Sand (Quartz + Calcium Carbonate + salts)
c. Tap Water (H2O + Cl2 + Salts)
d. Lemonade (sugar + H2O + Lemon)
4. Samantha conducted an experiment. She had a jar filled with salt, iron filings, and sand. First, she
separated the iron with a magnet. Next, she added water to dissolve the salt and filter the sand
out. Finally, she boiled off the water and was left with only salt. Was the matter inside of the jar:
a. A compound separated by physical means
b. A compound separated by chemical means
c. A mixture separate by chemical means
d. A mixture separated by physical means
5. Two students work on different substances in a science lab. Student 1 has a mixture and student 2
has a compound. Both students will separate the parts of their substances. Which best describes a
result of the separation process?
a. Only the mixture will go through a chemical change
b. Only the mixture will release heat when the parts are separated
c. Each part of the compound will gain mass during separation
d. Each part of the new compound will have different chemical properties.
6. Which combination of letters could be used as a chemical symbol for an element?
a. BR
c. Dy
b. ChFe
d. FeO
7. Which of the following is an example of a container that is filled with a pure substance rather than
a mixture?
a. A tire filled with air
c. A balloon filled with helium
b. A jar filled with salt water
d. A glass filled with chocolate milk
8. Which of the following is a mixture
a. Kool-Aid
c. Sugar
b. Salt
d. Hydrogen gas
9. Which formula represents a substance that is an element
a. CO
c. O
b. CO2
d. NH3
10. A student observes that the contents of a jar have many different substances, each with separate
chemical and physical properties. The contents of the jar can be classified as
a. An element
c. A solid
b. A mixture
d. A compound
11. Which of the following is a compound?
a. Salt water
c. Oxygen
b. Salt
d. The atmosphere
12. Which of the following about the separation of elements and compounds using chemical means is
true?
a. Elements and compounds cannot be changed into different substances.
b. Elements can be changed into different substances but compounds cannot
c. Elements cannot be changed into different substances and compounds can.
d. Both elements and compounds can be changed into new substances.
13. A pure substance can be made up of
a. Elements and mixtures
b. Compounds and elements
c. Compounds and mixtures
d. Compounds, mixtures, and elements
14. A scientist is studying a substance. During the investigation, the scientist makes these
observations about the substance.
 It is made up of two kinds of atoms
 It cannot be changed into simpler substances except by chemical means
 It is a pure substance with a constant composition
What kind of substance is the scientist studying?
a. An element
c. A mixture
b. A compound
d. A solution
Answer Key: 9.3 and 9.4
Carbon (C)
Element
Carbon
Dioxide
(CO2)
Salt (NaCl)
Compound
Oxygen (O2)
Element
Compound
Air
Mixture
(atmosphere)
Coca-Cola
Mixture
Salt Water
Mixture
Kool-Aid
Mixture
1. B
2. D
3. A
4. D
5. D
6. C
7. C
8. A
9. C
10. B
11. B
12. C
13. B
14. B
Ethanol
(C2H6O)
Baking Soda
(NaHCO3)
Compound
Methane
(CH4)
Nitrogen
(N2)
Sulfur (S)
Compound
Sulfate (SO4)
Compound
Hydrogen
(H2)
Glucose
(C6H1206)
Element
Compound
Element
Element
Compound