Download Chapter 1 Matter and Change

Unit 1
Introduction
Matter
and
Change
What is Chemistry?
Chemistry is the study of matter and its interactions.
We will study the following properties of matter:
• composition
• properties
• interactions
• changes
How will matter be studied?
Using the scientific method.
What is the Scientific Method?
Logical approach to exploring a problem or
question that has been raised through observation.
Designed to produce a solution or answer that can
be tested, retested, and supported by
experimentation.
What are the steps of the
Scientific Method?
1.State the problem.
2.Gather information about the problem.
3.Form a hypothesis.
4.Test hypothesis.
- variables
- controlled experiments
5.Gather and organize data and observations.
6.Interpret data.
7.Form a conclusion.
8.Replication.
What happens to a hypothesis?
Model: An explanation of how phenomena occur
and how data or events are related.
Theory: A broad generalization that explains a
body of facts or phenomena.
Scientific Law: Statement or mathematical
expression about behavior of the natural world.
Use the following terms to organize a Concept
Map for matter.
•Can it be separated?
•Is composition uniform?
•Can it be decomposed by
ordinary chemical means?
•Elements
•Compounds
•Mixtures
•Pure Substance
•Heterogeneous mixture
•Homogeneous mixture
•Air
•Stainless steel
•Blood
•Wood
•Water
•Sodium chloride
•Gold
•Oxygen
Matter
Matter – anything that has mass and volume.
How is matter classified?
Matter is broken down into two major categories
- Pure Substance
- Mixture
Pure Substance
- Have unique properties
- Cannot be separated by physical means
- There are two categories of pure substances:
Elements and Compounds
Elements
- simplest pure substances
- contain only one kind of atom
- cannot be broken down by physical or chemical
means
- unique physical and chemical properties
Compounds
- substance composed of 2 or more elements that
are chemically combined
- have unique chemical and physical properties
- can be broken down chemically (not physically)
- properties of elements that compounds are broken
down into do not resemble properties of original
compound
- always break down to the same proportion by
mass
Mixtures
- Collection of 2 or more pure substances
physically mixed together. (No chemical formula)
- Properties vary depending on what is in the
mixture
- Composition can vary (no definite proportion)
- There are 2 types of mixtures:
Heterogeneous
Homogeneous
Homogeneous Mixture
- Substances are distributed evenly throughout the
mixture
- All regions are identical in their composition and
properties
Heterogeneous Mixture
- Substances are not evenly distributed throughout
the mixture
- Some regions have different properties than
others
Classification of Matter
Matter is described by its properties
Extensive Properties
- Depend on how much of a substance there is
- Not useful in identifying the substance.
Intensive Properties
- Properties that do not depend on size.
- Can be useful in identifying the substance.
Comparing Extensive and
Intensive Properties
Physical Properties
- Characteristics that can be observed without
changing the substance.
- Melting point and boiling point are examples
Physical Change
- Change in a substance that does not involve
a change in the identity of the substance.
- Phase changes are examples:
solid to liquid
liquid to solid
liquid to gas
gas to liquid
solid to gas
gas to solid
-
melting
freezing
vaporization
condensation
sublimation
deposition
Phase Changes are also
called changes in state.
Plasma
There are 4 states of matter:
Solid
Liquid
Gas
Phase Diagrams
A phase diagram is a graph of pressure versus
temperature that shows the conditions under which
the phases of a substance exist.
The triple point of a substance indicates the
temperature and pressure conditions at which the
solid, liquid, and vapor of the substance can coexist
at equilibrium.
The critical point of a substance indicates the critical
temperature and critical pressure.
Phase Diagram
Phase Diagram
Phase Diagram for CO2
Changes of State - Summary
Water in Three States
Heating Curve for Water
Heat of Fusion: The amount of energy as heat
required to melt a solid at the solid’s melting
point
Heat of Vaporization: The amount of energy
as heat that is needed to vaporize a liquid at
the liquid’s boiling point at constant pressure
Chemical Properties
- characteristics that describe how a
substance interacts (or fails to interact) with
other substances.
Chemical Change
- also called a chemical reaction
- change that results in production of 1 or
more substances that differ in chemical
properties and composition from the original
substance
Chemical Reaction
Evidence of a Chemical Change
Comparison of Physical and
Chemical Properties
Comparing Physical and Chemical
Properties
Comparing Chemical and Physical
Changes
Periodic Table of the Elements
Review Questions
1.
2.
3.
4.
5.
Matter that has a definite shape and a definite volume is?
Why is air considered a mixture and not a compound?
How do compounds differ from mixtures?
Is each of the following a chemical or physical property?
A. Its mass is 124.3 g.
B. It is a shiny solid at room temperature.
C. It is easily etched by nitric acid.
D. It melts when heated to 670°C.
E. It is 31.7 centimeters long.
F. It is a good heat conductor.
G. It burns in air.
H. It is a good conductor of electrical energy
Describe the difference between a chemical change and a
physical change. Give one example of each kind of
change.