Chapter 1 and 3
Section 1.2
What Is Chemistry?
• The science that deals with the materials of
the universe and the changes these materials
undergo.
• The central science.
▪ Understanding most other fields of science
requires an understanding of chemistry.
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Section 1.4
The Scientific Method
Science
• Science is a framework for gaining and
organizing knowledge.
• Science is a plan of action — a procedure for
processing and understanding certain types of
information.
• Scientists are always challenging our current
beliefs about science, asking questions, and
experimenting to gain new knowledge.
▪ Scientific method is needed.
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Section 1.4
The Scientific Method
The Process that
lies at the center
of scientific
inquiry.
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Section 1.4
The Scientific Method
Scientific Models
Law
• Summarizes what happens.
Hypothesis
• A possible explanation for an observation.
Theory (Model)
• An attempt to explain why it happens.
• Set of tested hypotheses that gives an overall
explanation of some natural phenomenon. Return to TOC
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Chapter 3
Matter
CHAPTER
Section 3.1 3
Matter Table of contents
3.1 Matter
3.2 Physical and Chemical Properties and Changes
3.3 Elements and Compounds
3.4 Mixtures and Pure Substances
3.5 Separation of Mixtures
ADDITIONAL Particle Diagrams
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Section 3.1
Matter
▪ Anything that occupies space and has mass.
▪ States/phases of matter:
1) Solid
• Rigid
• Has a fixed volume and shape.
2) Liquid
• Has a definite volume but no specific shape.
• Takes shape of container.
3) Gas
• Has no fixed volume or shape.
• Takes the shape and volume of its container. Return to TOC
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Section 3.1
Matter
https://phet.co
lorado.edu/en
/simulation/st
ates-of-matter
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Section 3.2
Physical and Chemical Properties and Changes
Physical Properties
• The characteristics of matter that can be observed
without changing its chemical composition.
• Characteristics that are directly observable.
• Examples:
odor, color, volume, state/phase, density, melting
point, boiling point, malleability, electrical conductivity
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Section 3.2
Physical and Chemical Properties and Changes
Chemical Properties
• A substance’s ability to form new substances.
• Characteristics that describe the reactivity of the
sample of matter.
• Examples:
Flammability, acidity, iron can rust, hydrogen reacts
with metals
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Section 3.2
Physical and Chemical Properties and Changes
Concept Check
Classify each of the following as a physical or
chemical property.
physical ▪ Ethyl alcohol boils at 78℃
physical ▪ Hardness of a diamond
chemical ▪ Sugar can ferment to form alcohol
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Section 3.2
Physical and Chemical Properties and Changes
Physical Change
• Change in the form of a substance, not in its chemical
composition.
• Examples: melting, freezing, bending, cutting
Chemical Change
• A given substance becomes a new substance with
different composition and properties.
• Example: glucose reacting with oxygen to form carbon
dioxide and water
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Section 3.2
Physical and Chemical Properties and Changes
Concept Check
Which of the following is/are example(s) of a chemical
change?
▪ Pulverizing (crushing) rock salt
▪ Burning of wood
▪ Dissolving of sugar in water
▪ Melting a popsicle on a warm summer day
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Section 3.2
Physical and Chemical Properties and Changes
Concept Check
Classify each of the following as a physical or
chemical change.
chemical ▪ Milk spoiling
physical ▪ Iron metal melting
chemical ▪ Iron combining with oxygen to form rust
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Section 3.3
Elements and Compounds
Element
• A substance that cannot be broken down into other
substances by chemical methods.
• Examples: Iron (Fe), aluminum (Al), oxygen (O),
and hydrogen (H)
• All of the matter in the world around us contains
elements.
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Section 3.3
Elements and Compounds
Compound
• A substance composed of a given combination of
elements that can be broken down into those
elements by chemical methods.
• Examples: H2O, CO2, C6H12O6
• A compound always contains atoms of different
elements.
• A specific compound always has the same
composition (combination of atoms).
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Section 3.3
Elements and Compounds
Concept Check
Which of the following are compounds?
H2O, N2O4, NaOH, O2, HF
All of them except O2
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Section 3.4
Mixtures and Pure Substances
Pure Substances
• Elements
• Compounds
• Examples: water (H2O), carbon dioxide (CO2),
hydrogen (H2), aluminum (Al)
• Compounds can be separated into elements by
chemical methods.
• Example: H2O be can separated into hydrogen and
oxygen using electrolysis.
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Section 3.4
Mixtures and Pure Substances
Mixtures
• Two or more substances (element and/or compound)
• Have variable composition
• Examples: orange juice, salad, wood
• Can be separated into pure substances by physical
means.
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Section 3.4
Mixtures and Pure Substances
Homogeneous Mixture
• Same throughout; does not vary in composition from
one region to another.
• Having visibly indistinguishable parts.
Heterogeneous Mixture
• Contains regions that have different properties from
those of other regions.
• Having visibly distinguishable parts.
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Section 3.4
Mixtures and Pure Substances
Concept Check
Identify the homogeneous mixture(s).
▪ milk
▪ somtam
▪ soil
▪ soup
▪ water
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Section 3.5
Separation of Mixtures
Mixtures can be separated based on different physical
properties of the components.
Example 1: Example 2:
Can separate based Can separate based on
on difference in difference in color,
color. shape, taste, etc. Return to TOC
Section 3.5
Separation of Mixtures
Some Separation Techniques
• Evaporation or distillation
Separates dissolved substance from water.
Based on difference in boiling temperature
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Section 3.5
Separation of Mixtures
• Filtration
Separates liquid from solid.
Based on difference in
phase of matter
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Section 3.5
Separation of Mixtures
The Organization
of Matter
• Physical method
used to separate a
mixture.
• Chemical method
used to separate a
compound. Return to TOC
PARTICLE DIAGRAMS
(NOT IN TEXTBOOK)
We can represent elements, compounds and mixture
using particle diagrams.
Element Element (diatomic) Compound Mixture
Section 3.5
Separation of Mixtures
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