This document summarizes key points about compounds, mixtures, and the differences between physical and chemical properties and changes. It discusses: - Compounds are chemical combinations with fixed ratios while mixtures can have varying ratios. - Mixtures can be homogeneous (uniform) or heterogeneous (non-uniform) and include solutions, colloids, and suspensions. - Physical properties describe observable characteristics without changing a substance's identity, while chemical properties involve substance changes. - Physical changes alter appearance/state but not composition, while chemical changes produce new substances with different properties than original reactants.

1. Chapter 2.1/2.2 Key Points
Max Waldbaum

2. Compounds and Mixtures
Compounds Mixtures
• Are a chemical combination • Are a physical combination
• Can only be broken down • Can only be broken down
chemically physically
• Always in a fixed ratio
• Can be in any ratio
(e.g. H20)
(e.g. Cereal)
• All compounds have a
unique set of properties • No one unique set of
(Characteristic properties
properties, which are
independent of amount)

3. Types of Mixtures
Homogeneous Mixture Heterogeneous Mixture
• Very evenly distributed • Not uniform throughout
substances • Parts are noticeably
• Appears to only contain one different
substance e.g. Honey Bunches of Oats
e.g. Stainless Steel (Made of Cereal ( Made with different
iron, chromium, and parts that look clearly
nickel, but looks uniform) different)
• Solutions and Colloids are • Suspensions are
Homogeneous Heterogeneous

4. Heterogeneous and Homogeneous
Mixtures Classifications
Solutions Suspensions Colloids
• A solution is when • A suspension is a • A colloid has
substances heterogeneous particles larger than
those of a
dissolve creating a mixture that
solution, but
homogeneous separates into smaller than those
mixture layers over time of a suspension. It is
a homogenous
mixture
e.g. Lemonade e.g. Mixtures that
e.g. Homogenized
(Sugar and lemon State “Shake Well” milk (the fat
juice dissolved in (If not, the remains dispersed
water) different parts of throughout the
the mixture will milk)
layer)

5. Classifications of Matter
Matter
Pure Substance Mixture
Homogeneous Heterogeneous
Element Compound
Mixture Mixture
One Substance Chemical Mix
Solution, Colloid Suspension
(Au) (H2O)

6. Physical Properties
• A Physical Property is a characteristic of a material
• Examples of Physical Properties are .....
– Viscosity (Residence to flowing- e.g. honey has a high viscosity)
– Conductivity (Ability to allow heat to flow – e.g. metal has a high
conductivity)
– Malleability (Ability of a solid to be hammered without shattering –
e.g. Gold is malleable)
– Hardness (Which material is harder – e.g. scratch test)
– Melting/Boiling Points
– Density (How dense the material is – g/mL)

7. Using Physical Properties
• Physical Properties are mainly used to...
1. Identify a Material
2. Choose a material for a specific purpose
3. Separate the substances in a mixture
• Physical properties are key in exercising these
steps, which are used in many scientific
findings and labs

8. Distillation
• A process that separates the substances in a
solution based on Boiling Point

9. Filtration
• A process that separates particles based on
the size of their particles and/or solubility

10. Evaporation
• A process used to isolate a solid dissolved in a
liquid. Property: Solubility
• Ex: NaCl + Water
– (Sodium Chloride)
• Table Salt
• DISCLAIMER: You are not going to isolate a pure sample of all
components of the mixture

11. Observing Chemical Properties
• Chemical properties can only be observed
when the substances in a sample of matter
are changing into different substances
– Flammability
• Is a materials ability to burn in the presence of oxygen
– Reactivity
• How easily a substance combines with another
substance (Rust & Oxygen)

12. Recognizing Chemical Changes
• Common types of evidence:
– Change in color
– Production of Gas
– Formation of Precipitate

13. Difference Between Chemical and
Physical Changes
• Chemical changes:
– Composition of a substance changes
• Physical Changes
– Composition remains the same

14. Questions for Test
• What is a physical property?

15. Questions for Test
• What is a chemical property?

16. What is a Physical Change?

17. What is a chemical change?

18. What are the four ways to recognize a
chemical change?