n
What instrument would you use to measure temperature? n
Which of the following is a unit of volume?
A. gram (g) C. meter (m)
B. second (s) D. liter (l) n
What characteristic of matter can you
measure using a graduated cylinder?
Chapter 2 Properties of Matter 2

n
Which of the following is not studied in chemistry.
A. Composition of matter
B. Reactions of Substances
C. Properties of Materials
D. Motion of Large objects.
Chapter 2 Properties of Matter 3

2.1 What is Science?
2.2 Using a Scientific Approach
2.3 Measurement purplish color = ? write in your notes
Chapter 2 Properties of Matter 4

n
Vocabulary: n   n   n   n   pure substance element atom compound n   n   n   heterogeneous mixture homogeneous mixture n   n   n   solution suspension colloid
Objectives: n
Classify pure substances as elements & compounds. n   n   n   n   n
Describe the characteristics of an element & the symbols used to identify elements.
Describe the characteristics of a compound.
Distinguish pure substances from mixtures.
Classify mixtures as heterogeneous or homogeneous.
Classify mixtures as solutions, suspensions, or colloids.
Chapter 2 Properties of Matter 5

v   matter - anything that takes up space and has mass v   based on their compositions, materials can be divided into pure substances and mixtures
Chapter 2 Properties of Matter 6

v   pure substance (or simply a substance) matter that always has exactly the same composition v   fixed, uniform composition v   every sample has same properties v   can be classified into 2 categories: v   elements v   compounds
Chapter 2 Properties of Matter 7

v   millions of known substances, but only about
100 elements v   element substance that CANNOT be broken down into simpler substances
§   only 1 type of atom à fixed composition
§   no 2 elements contain
same type of atom
Chapter 2 Properties of Matter 8

v   at room temperature (20°C, 68°F, 300K) n   most are solids n   some are gases
(e.g. oxygen & nitrogen) n   only 2 are liquids,
bromine & mercury
Chapter 2 Properties of Matter 9

v
v
Chapter 2 Properties of Matter 10

v
1 or 2 letters: 1 st capitalized, 2 nd not v   some based on Latin names n   symbol for gold is Au because Latin name for gold is aurum v   sometimes name gives clue to properties n   hydrogen from Greek words hydro (water) & genes (forming)
Chapter 2 Properties of Matter 11

Chapter 2 Properties of Matter 12

v   compound substance that is made from two or more simpler substances and CAN be broken down into those simpler substances v   simpler substances are
either elements or compounds
Chapter 2 Properties of Matter 13

v   always contains 2 or more elements joined in a fixed proportion v   properties of a compound differ from those of the substances from which they are made
Chapter 2 Properties of Matter 14

v   example: water (H
2
O)
Chapter 2 Properties of Matter 15

v   example: water (H
2
O)
§   compound of 2 elements hydrogen (H) & oxygen (O)
H H
O
Chapter 2 Properties of Matter 16

v   example: Water (H
2
O)
§   H
2
& O
2
both gases at room temperature
§   H
2
can fuel a fire & O keep a fire burning
2
can
§   H
2
O does not burn or help other substances burn.
Water decomposes into its component elements, hydrogen & oxygen, when direct electrical current is passed through it. Volume of hydrogen (right) is twice the volume of oxygen (left).
Chapter 2 Properties of Matter 17

n   example: silicon dioxide (SiO
2
) n   always 2 O atoms for each silicon (Si) atom n
O colorless gas n
Si gray solid n   compound found in most light-colored grains of sand
SiO
2 is a colorless, transparent solid
Chapter 2 Properties of Matter 18

n   matter that doesn‘t always have the same composition n   tend to retain some of
properties of their
individual substances
Chapter 2 Properties of Matter 19

n   properties of a mixture can vary because the composition of a mixture is not fixed
Chapter 2 Properties of Matter 20

n   no matter how well you stir, substances that make up mixture will not be evenly distributed n   can be classified by how well parts are distributed throughout mixture n   homogeneous n   heterogeneous
Chapter 2 Properties of Matter 21

n   homogeneous mixture - substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another n   appears to contain only one type of substance n   example: swimming pool water:
H
2
O + substances that dissolve in water
Chapter 2 Properties of Matter 22

n
Greek words hetero ( “ different ” ) & genus
( “ kind ” ) n   heterogeneous mixture parts of the mixture are noticeably different from one another
Chapter 2 Properties of Matter 23

Chapter 2 Properties of Matter 24

Stainless steel serving spoon is a homogeneous mixture of iron, chromium, and nickel. It is difficult to distinguish one substance from another.
Chapter 2 Properties of Matter 25

Sand is a heterogeneous mixture. It is not the same throughout.
Chapter 2 Properties of Matter 26

pure substances
anything that takes up space & has mass mixtures elements compounds homogeneous heterogeneous
Chapter 2 Properties of Matter 27

matter anything that takes up space & has mass pure substances matter that always has exactly the same composition mixtures matter that doesn‘t always have the same composition elements substances that
CAN ʼ T be broken down into simpler substances. compounds substances made from 2 or more simpler substances &
CAN be broken down. homogeneous heterogeneous even distribution difficult to distinguish one substance in the mixture from another. parts of the mixture are noticeably different from one another.
Chapter 2 Properties of Matter 28

Chapter 2 Properties of Matter 29

hydrogen atoms oxygen atoms hydrogen atoms
(a) an element
(hydrogen)
(b) a compound
(water)
(c) a mixture
(H & O)
Chapter 2 Properties of Matter
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3 rd Edition, 1990, page 68
(d) a mixture
(H & O)
30

Nitrogen consists of molecules consisting of 2 atoms of nitrogen:
Oxygen consists of molecules consisting of 2 atoms of oxygen:
Water consists of molecules consisting of 2 hydrogen atoms & 1 oxygen atom:
Argon consists of individual argon atoms:
Carbon dioxide consists of molecules consisting of 2 oxygen atoms & 1carbon atom:
Neon consists of individual neon atoms:
Helium consists of individual helium atoms:
Chapter 2 Properties of Matter
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 35
N
2
O
2
H
2
O
Ar
CO
2
Ne
He
31

n   size of the particles in a mixture has an effect on the properties of that mixture
Key Concept: n
Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.
Chapter 2 Properties of Matter 32

n   solution mixture that forms when substances dissolve and form a homogeneous mixture n   example: sugar dissolved in water
spoonful of sugar in a glass of hot water & stir, the sugar dissolves in the water à homogeneous mixture of sugar & water
Chapter 2 Properties of Matter 33

n   n
Properties of liquid solutions: Particles small so … n   n   do not separate into distinct layers over time. none of the substances in the solution are trapped in the filter. n   can see through because light passes through them without being scattered in all directions.
Particles in a solution are too small to settle out of solution, be trapped by a filter, or scatter light.
Chapter 2 Properties of Matter 34

n   suspension heterogeneous mixture that separates into layers over time n   examples: sand mixed with water
Chapter 2 Properties of Matter 35

n
Properties of a suspension: Because suspended particles are large … n   suspended particles settle out of mixture
(form layers) n   n   can use a filter to separate out suspended particles can scatter more light in all directions (cloudy)
Chapter 2 Properties of Matter 36

n   colloid - contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension n   e.g.
homogenized milk, fog (water droplets in air)
Chapter 2 Properties of Matter 37

n
Properties of a colloid: n   does not separate into layers n   can ʼ t use a filter to separate the parts n   scatters light (cloudy, opaque)
Chapter 2 Properties of Matter 38