1. Substances, Mixtures, Properties and Changes of Matter
Section 1.4 – Pages 8 -13

2. What is Chemistry?
Chemistry is the study of the composition, structure and behavior of matter
Composition – what is matter made up of?
Structure – how is the matter put together?
Behavior – how do different types of matter interact?
Matter = anything that has mass and takes up space

3. The Atom All matter is made up of small particles called atoms. Atom:
The fundamental unit of which elements are made.

4. Pure Substances
Substance – contains only one kind of matter; cannot be separated into other kinds of matter by any physical process.
There are two types:
Elements
Compounds
Coal = Carbon

5. Elements
Element: simplest form of matter, cannot be decomposed into simpler substances by any chemical reaction; located on the periodic table
Examples – oxygen, gold, sulfur
Bars of Gold

6. Elements in the Human Body

7. Compounds
Compounds: contains 2 or more elements chemically combined; can only be separated using chemical reactions
Examples – water (H2O), sugar (C12H22O11), carbon dioxide (CO2)
Sucrose

8. Law of Definite Proportions
A pure compound always contains definite or constant proportions of the elements by mass.
Example:
H2O (water) vs. H2O2 (hydrogen peroxide)

9. Molecules
Molecule:
A collection of atoms bonded together that behave as a unit.
All molecules of the same compound are identical.

10. Mixtures
Mixture – physical blend of 2 or more substances; can be easily separated by heating, filtering, drying, sorting, dissolving, etc.
There are two types:
Heterogeneous
Homogeneous

11. Homogeneous Mixture
Homogeneous Mixture – uniform composition; any sample has the same composition (aka solution)
Examples - Salt water, air, brass (alloy)
Salt Water Solution

12. Heterogeneous Mixture
Heterogeneous Mixture – not uniform in composition; consists of physically distinct parts, each with different properties.
Examples – salsa, concrete, toss salad
Chex Mix!

13. Review – Classifying Matter
Chemistry is the study of the __________________, ___________________ and ___________ of matter.
Matter is anything that has ____________ and ___________________.
Classify the following as either an element, compound, homogeneous mixture or heterogeneous mixture.
A penny
Silicon
Apple juice
Vanilla yogurt with M & M’s
Carbon dioxide

14. Separation of Mixtures
Two Examples:
Distillation: a separation process that depends on the different boiling points of the substances.
Filtration: separation of a solid from a liquid by using filter paper

15. Properties of Matter
Physical Properties: a characteristic of matter that can be observed or measured w/o changing the samples composition
Examples – density, odor, color, melting pt, solubility, state, etc.
Chemical Properties: the ability or inability of a substance to combine with or change into one or more new substances (reactivity)
Examples – ability of iron to rust, flammability

16. Intensive vs. Extensive Properties
Intensive Property – independent of the amount of substance present
Examples – density, boiling pt., melting pt.
Extensive Property – dependent upon the amount of substances present
Examples – mass, length, volume

17. Physical or Chemical Property
Classify the following as either physical or chemical properties:
The boiling point of a certain alcohol is 78 °C.
Diamonds are very hard.
Sugar ferments to form alcohol.
A metal wire conducts an electric current.

18. Changes of Matter
Physical Changes: a type of change that alters the physical properties of a substance not its composition (identity)
Example s– cutting of paper, grinding, melting, dissolving, etc.
Chemical Changes: chemical reactions; a process involving one or more substances changing into new substances; “irreversible”
Examples – rusting, photosynthesis, burning

19. Evidence of Chemical Changes:
Creation of a gas
Odor is released
Color change
Energy is absorbed or released

20. Three States of Matter
Solid: definite shape and volume; particles are tightly packed together forming a rigid structure; incompressible
Liquid: definite volume and takes shape of its container; particles “flow”; incompressible
Gas: takes shape and volume of its container; particles are far apart; can be compressed