1. Elements, Compounds
& Mixtures!

2. 1. Pure Substances
Pure substances are substances in which there is only one type of particle.
These particles are called atoms.
The only two things that are pure substances are:
1. Elements
2. Compounds

3. 2. What are Elements?
An element is a pure substance that cannot be separated or broken down into simpler substances by physical or chemical means.
What are examples of elements?
Anything that is on the Periodic Table of Elements.
Examples: Gold (Au), Silicon (Si), Neon (Ne), Silver (Ag), sulfur (S) S Au Ag Fe

4. The Periodic Table of Elements
Everything that is on this table is an element. If it isn’t on this table, it isn’t an element!

5. 3. Identifying Elements
Elements are categorized by unique properties on the Periodic Table.
They are arranged in order by their number of protons. (More on this later!)
Each element has unique properties like melting point, boiling point, and whether it is metal, nonmetal or metalloid.

6. What are compounds?
A compound is a pure substance composed of two or more elements chemically combined.
This means they were formed by a chemical reaction.
Elements
Compounds

7. Familiar Compounds Compound Elements Combined Formula Table salt
Sodium and Chlorine
NaCl
Water
Hydrogen and Oxygen
H2O
Vinegar
Hydrogen, Carbon, and Oxygen
C2H4O2
Carbon dioxide
Carbon and Oxygen
CO2
Baking soda
Sodium, Hydrogen, Carbon and Oxygen
NaCHO3

8. ELEMENTS MAKE COMPOUNDS!!
5. Forming a Compound
Compounds are formed by combining two or more elements.
Elements are “stuck together” by chemical bonds
When this happens, new properties are formed; the elements lose their original properties.
You end up with one new thing!
ELEMENTS MAKE COMPOUNDS!!

9. Example: Formation of NaCl+
Sodium Chloride, or table salt, is a white solid. It dissolves easily in water and is safe to eat.
Sodium is a soft, silvery white metal that reacts violently with water.
Chlorine is a poisonous, greenish-yellow gas.
**Compounds have properties that differ from those of the elements that form it!**

10. 6. How are compounds separated?
Compounds are broken apart by breaking chemical bonds.
You separate them by forcing another chemical reaction to happen
CHEMICAL CHANGE!!!!
Add heat, electricity, another compound or element as a chemical reaction
Remember compounds are specific recipes!

11. Breaking Chemical Bonds

12. What is a mixture?
A mixture is when 2 or more substances are combined but do not chemically react.
THE SUBSTANCES KEEP THEIR OWN PROPERITES!!
We say that we MIX to form them.

14. Examples of Mixtures Iced tea powder and water Granite Milk
Oil and vinegar

15. 3 Properties of a Mixture
It is NOT a chemical change
It can be separated by physical means
Ratio of each substance does NOT matter

16. Separation of a Mixture
Pick apart or straining
Evaporation
Filter
Centrifuge
Distillation (boiling the solvent to separate it from the solute)
Magnetism (like iron)

17. Separating a mixture is a PHYSICAL CHANGE because there are no chemical reactions or changes - parts keep their properties!!

18. 10. Types of Mixtures Homogeneous (Homo = same)
Heterogeneous (Hetero = different)
The mixture appears to be the SAME throughout
The mixture appears to be DIFFERENT throughout

19. Examples HOMOGENEOUS Milk Stainless steel Oil Brass (Cu + Zn)
HETEROGENEOUS
Oil & vinegar
Concrete
Soil
Pizza, Cereal

21. YES NO YES: NO: YES: NO: All matter
Can it be separated by physical means?
Mixtures
Pure substances
Is the composition uniform?
Can it be decomposed by ordinary chemical means?
YES:
NO:
Homogeneous Mixtures
(air, sugar in water, stainless steel)
YES:
NO:
Heterogeneous Mixtures
(granite, wood, blood)
Compounds
(water, sodium chloride, quartz)
Elements
(gold, aluminum, oxygen, chlorine)
DIFFERENT THROUGHOUT
SAME THROUGHOUT