1. What is Matter?

2. Objectives
Explain the relationship between matter, atoms, and elements
Distinguish between elements and compounds
Describe molecules, and explain how they are formed
Interpret and write some common chemical formulas
Categorize materials as pure substances or mixtures

3. What is chemistry and matter?
Chemistry: the scientific study of the composition, structure, and properties of matter and the changes that matter undergoes.
Matter: anything that has mass and takes up space.

4. Element: a substance that cannot be separated or broken down into simpler substances by chemical means.
Atom: the smallest unit of an element that maintains the properties of that element
Compound: a substance made of atoms of two or more different elements that are chemically combined.
The word atom is derived from the Greek word, a means not , tomos means cutting. Literally meaning indivisible.

6. The human body is composed of living cells, which in turn contain large moldecules and compounds made up of elements.

7. Molecule: the smallest unit of a substance that keeps all of the physical and chemical properties of that substance.
A compound is made of two or more different elements, but a molecule may be of the same elements or different elements.

8. Remember: some elements occur singly in nature
Ex) Neon
The atoms of other elements combine to form polyatomic molecules
Ex) O2 H P4

9. Molecules can be represented by:
Formula
Physical models
Chemical formula- a combination of chemical symbols and numbers to represent a substance
C16 H10 N2 O2 Indigo
C8 H10 N4 O2 Caffeine

10. Mixture- a combination of two or more substances that are not chemically combined
Pure substance- a sample of matter, either a single element or a single compound, that has definite chemical and physical properties
*Elements and compounds are pure substances, but mixtures are not

11. Solids can mix with liquids
Mixtures can be separated into their components
Heterogeneous mixture- substances aren’t mixed uniformly and are not evenly distributed
Ex) flour in water – a suspension
Homogeneous mixture- components are evenly distributed, mixture is same throughout
Ex) sugar in water

12. Liquids can mix with liquids
Gasoline is a liquid mixture of ~ 100 liquids
Comprised of miscible liquids
Miscibility- only miscible liquids that are combined (ex. Ethylene glycol and water) can dissolve in each other.
They form a solution (a homogeneous liquid mixture)

13. Immiscible- liquids such as oil and water or toluene and water that are practically insoluable
Instead, they form two layers, with the denser liquid on the bottom.

14. Gases can mix with liquids
Ex) Lava
The molten rock in some types of volcanoes contains large quantities of gas. Pumice, a solid foam that occurs naturally on Earth, is a volcanic rock formed by the violent separation of these extremely hot gases from lava.
As the exploding lava cools, it traps the bas bubbles.
Some pumice is so soft that it is spongy, and has such a low density that it floats on water

15. 2.2
Objectives
Distinguish between the physical and chemical properties of matter, and give examples of each
Perform calculations involving density
Explain how materials are suited for different uses based on their physical and chemical properties
Describe characteristic properties

16. Physical properties
Physical properties identify things by describing matter
Examples:
Color
Shape
Height
Mass
Volume
density

17. More examples of physical properties:
Melting point (temperature and pressure at which a solid becomes a liquid)
Boiling point (temperature and pressure at which a solid becomes a liquid)
Strength
Hardness
Ability to conduct electricity
Magnetism
Heat

18. . substance Melting point º Celsius Boling point C 3550 4827 Au 1063
A characteristic of any pure substance is that its boiling point and melting point are constant if the pressure remains the same
substance
Melting point
º Celsius
Boling point C
3550
4827 Au
1063
2970 Fe
1535
2750 Hg
-39
357 N
-209
-196 O
-218
-183
NaCl
801
1413
H2O
100 .

19. Density= Mass
Volume
Density depends on the arrangement of atoms within that sample of matter
Density determines whether an object will float or sink

20. Densities of some substances
Chemical formula
Density in g/cm3
Air, dry
Mixture
Brick
1.9
Gasoline
0.7
Helium He
Ice
H20
0.92
Iron Fe
7.86
Lead Pb
11.3
Nitrogen N2
Steel
7.8
Water
1.00

21. The density of a liquid or a solid is affected only slightly by a change in temperature or pressure.
In a gas however, an increase in temperature or a decrease in pressure significantly reduces the density of a gas

22. Chemical Properties
Chemical property- describes how a substance changes into a new substance either by combining with other elements or by breaking apart into new substances.
Examples:
Reactivity of element with other compounds (oxygen, acid, water, other)
Oxidation of Fe creates rust
Flammability (ability to burn)

23. Changes of matter Objectives: Explain physical change, give examples
Explain chemical change, give examples
Compare and contrast physical and chemical changes
Describe how to detect whether a chemical change has occurred

24. A physical change affects one or more physical properties of a substance without changing its identity
Ex) breaking chalk
Getting a hair cut
Dissolving sugar
Melting ice
Sanding wood
Crushing a can
Mixing oil and vinegar

25. Mixtures can be physically separated because the components are not chemically combined.
Distillation device- can separate components of mixtures that have different boiling points. When heated, the component that boils and evaporates first, separates from the mixture and collects in the receiving tank

26. Magnets can be used to separate mixtures that have components containing iron.
Centrifuge- tool used to separate mixtures. It spins a sample of a mixture rapidly until the components of the mixture separate

27. Changes in the state of matter are physical because they do not change the identity of the substance!!!

28. Chemical changes
A change that occurs when a substance changes composition by forming one or more new substances.
Ex) soured milk (produces odor)
Effervescent tablets (produce CO2)
(copper pennycopper carbonate)
Oxidation- (iron  rust)
Fruits ripening
Food being digested

29. Chemical changes form new substances that have different properties
Ex) baking a cake

30. Chemical changes can be detected
Clues suggesting that a chemical change occurred:
Change in odor or color
Fizzing
Foaming
Production of: sound, heat, light, odor

31. Chemical changes cannot be reversed by physical changes
Ex) you can not unbake a cake
However, some chemical changes can be reversed under the right conditions by other chemical changes.