Transcript Unit 1 science of chemistry

Unit 1
The Science of Chemistry and Matter
 What is Chemistry?
Energy
Elements
Laboratory
Compounds
 POD: Discuss with the person next to you different
ways you think chemistry is present in your everyday
life and write it down on your pod.
Classification of matter
Objectives:
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2.
3.
4.
5.
6.
7.
Relate chemistry to everyday life.
Identify traditional areas of study in chemistry.
Define matter.
Categorize samples of matter as a mixture or a substance.
Distinguish between homogeneous and heterogeneous
mixtures.
Describe ways components of a mixture can be separated
Explain the difference between a compound and an
element.
 Chemistry is the study of the composition of matter
and the changes matter undergoes.
 Matter: anything that has mass and occupies space.
 There are five traditional areas of study for chemistry
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Organic chemistry: study of chemicals containing carbon.
Inorganic chemistry: study of chemicals that do not contain
carbon.
Biochemistry: study of processes that take place in
organisms.
Analytical chemistry: focuses on composition of matter
Physical chemistry: describes behaviors of chemistry.
 Chemistry far and wide:
 Materials: plastic, glass, ceramics, perfumes, food, etc.
 Energy: fossil fuels, food, solar batteries, nuclear
 Medicine: penicillin, aspirin, Vitamin C
 Agriculture: fertilizer, pesticides, growth hormones
 Environment: ozone, carbon dioxide- global warming,
pollution
 Astronomy: composition of planets and stars
 Classification of matter
 Mixtures: a physical blend of two or more components.
Ex. Salad, pizza, milkshake and air
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Heterogeneous mixtures: the composition is not uniform
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Homogeneous mixtures: composition is uniform
throughout. Also called solutions.
In a solution we have a solute (substance being dissolved) and
a solvent (substance dissolving solute)
Water is the universal solvent
Most are liquids
Some are solids. Example alloys of different metals like brass,
an alloy of copper and zinc.
 For tomorrow research what other types of alloys
we use.
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Some are gases like the air
Figure 1.4a
MIXTURES
HOMOGENOUS
HETROGENOUS
Separation of mixtures
• Separate mixtures based on different
physical properties of the components
Different Physical Property
Technique
Boiling Point
Distillation
State of Matter (solid/liquid/gas)
Filtration
Adherence to a Surface
Chromatography
Volatility
Evaporation
Density
Centrifugation &
Decanting
Distillation
Filtration
 Pure Substances: have fixed composition.
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Elements are the simplest form of matter that has its
unique set of properties.
 Ex. Gold is an element. All atoms of gold have the
same properties.
 Elements are shown in the Periodic Table.
 There are more than 100 elements, most of them occur
naturally.
 Elements are represented by one (a capital letter) or
two letter symbols(a capital letter and a lowercase
letter).
 Ex. C: carbon
Co: cobalt
Compounds is a substance that contains two or more
elements chemically combined in a fixed proportion.
•Represented by chemical formulas using symbols
of elements present in compound and subscripts
indicated how many atoms of each element is
present.
Ex. H2O: water
CO: carbon monoxide
CO2: carbon dioxide
 Learning Check:
1.
How do elements relate to compounds?
2. How do elements and compounds relate to mixtures?
3. What is the main difference between pure
substances and mixtures?
 Learning Check:
1. How do elements relate to compounds? Compounds are
made from elements chemically combined.
How do elements and compounds relate to mixtures?
Elements and compounds physically combine to form a
mixture.
3. What is the main difference between pure substances and
mixtures?
Pure substances have a fixed composition and the
composition of mixtures may vary.
2.
Classwork: p53 #1-3
HW: Bring tomorrow any sample of matter
and share with the class how you would
classify the sample and why. (Don’t use
water as an example, too easy!!)
Changes in matter
1.
2.
3.
4.
5.
Identify properties as extensive or intensive.
Define a physical property and a chemical property.
Describe a physical change.
Describe what happens during a chemical change.
Identify clues that a chemical change has taken
place.
 Changes in matter
 Physical change : same substance remains after
change.
 Ex. Pounding, cutting, dissolving
 Changes of state: melting, boiling, condensing, etc.
 Chemical change: a new substance (different characteristics)
appears after the change. (a chemical reaction)
 Evidence of chemical change
 Production of gas (observed as bubbles or change of odor)
 Release or absorption of energy (change in temperature or
giving off light)
 A color change
 Formation of a precipitate (solid formed when two clear
solutions combine and become cloudy)
 Ex. Burning, digestion, fermentation
 During a chemical reaction, mass of products is equal to mass
of reactants: law of conservation of mass.
 Physical property: quality of a substance that can be
observed or measured without changing the
substance’s composition. Ex. Length, color,
temperature
 Extensive: depend on amount of matter present. Ex.
Mass, length, volume
 Intensive: do not depend on amount of matter present.
Ex. Density, color, malleability (can be hammered),
ductility (can be turned into wires), conductivity,
melting point.
 Chemical property : describes the behavior of a
substance undergoing a chemical change. Describes
how it reacts with other materials like air, water, and
acids.
 Characteristics could be: acidity, flammability, reactivity,
oxidizing ability, explosiveness.
 Indicating it does not react is also a chemical property.
 Energy and change
 Energy is the capacity to do work. Always involved when
there is a change in matter.
 Endothermic and exothermic processes
 Endothermic: energy is absorbed from the
surroundings. (Ex. Boiling water)
YouTube - "Cool" Reaction: Ammonium Thiocyanate
and Barium Hydroxide Octahydrate
 Exothermic: energy is released to the surroundings.
(Ex. fire)
YouTube - Exothermic reaction Potassium
Permanganate
 Learning check:
1.
Classify the following as a chemical or physical property
a.
b.
c.
d.
e.
2.
Is red
Reacts with water
Boils at 88C
Dissolves in gasoline
Is corrosive
Classify the following as a chemical or physical change
a.
b.
c.
d.
e.
Alcohol evaporating
An explosion
Digesting food
Salt dissolving in water
Grass growing
 Learning check:
1.
Classify the following as a chemical or physical property
a.
b.
c.
d.
e.
2.
Is red
Reacts with water
Boils at 88C
Dissolves in gasoline
Is corrosive
physical
chemical
physical
physical
chemical
Classify the following as a chemical or physical change
a.
b.
c.
d.
e.
Alcohol evaporating physical
An explosion
chemical
Digesting food
chemical
Salt dissolving in water physical
Grass growing
chemical
 Classwork: pg 62 #6-8
Unit 1
The Science of Chemistry and Matter