Transcript Matter and Change

Matter and
Change
Chapter 1
Objectives
• Define Chemistry
• Define properties of matter
Objectives
• Identify and explain physical properties
•
•
•
•
•
Density
melting point
boiling point
Conductivity
Malleability
• Identify and explain chemical properties
• the ability to form new substances.
• Distinguish between chemical and physical
changes.
Objectives
– Explain the difference between pure
substances (elements and compounds) and
mixtures.
– Differentiate between heterogeneous and
homogeneous mixtures.
– Describe the three normal states of matter
(solid, liquid, gas) in terms of energy, particle
motion, and phase transitions.
Introduction to Chemistry
• Chemistry – the
study of matter and
the changes it
undergoes
• the “central
science”
Matter
• Anything that
takes up space
and has mass
The States of Matter
SOLID
LIQUID
GAS
PLASMA
States of Matter
State of Matter
Volume
Shape
Solid
Definite
Definite
Liquid
Definite
Indefinite
Gas
Indefinite
Indefinite
Plasma
Indefinite
indefinite
Changes in State
• Name of Transitions
between states of matter:
– Melt/freeze
– Boil/Condense
– Sublimation/deposition
• Mostly obtained by
heating or cooling (add or
remove energy)
Condense
Freeze
Melt
Solid
Boil
Liquid
Gas
Classification of Matter
Matter
• Matter is classified into different categories
based on the composition of the material
• Mixtures: matter consisting of a variable
composition
• Pure substances: matter made of definite
composition
Mixtures
• Are heterogeneous or
homogeneous
• Are a physical blend of
two or more pure
substance
• Have variable
composition
• Can be separated by
physical change
• Separation Techniques
depend on type of mixture
Heterogeneous Mixtures
• Uneven blend of two
or more pure
substances
• Different substances
or phases of matter
can be visibly seen
• Can be separated by
physical means like
filtration
Homogeneous Mixtures
• Also known as
solutions
• Even blend of two or
more pure substances
• Look uniform
throughout the mixture
• Can be separated by
physical means like
distillation,
crystallization or
chromatography
Separation Techniques
Heterogeneous
Filtration
Homogeneous
Distillation
Crystallization
Chromatography
Study Buddy Review
• What is a mixture?
• What is the difference between a homogeneous and
heterogeneous mixture?
• Provide an example of homogeneous and heterogeneous
mixture.
Pure Substances
• Matter made of
material with a
unique set of
chemical and
physical properties
• Have constant
composition
• Cannot be separated
by physical change
• Are elements or
compounds
Elements
• Pure substances that cannot be separated into
simpler substances by a chemical change
Compounds
• Substance that contains
two or more elements
chemically combined in
fixed (constant)
proportions
• Can be separated into
elements by chemical
change
• Types: covalent or ionic
http://cwis.nyu.edu/pages/mathmol/modules/water/water.html
Study Buddy Review
• What is a pure substance?
• What is the difference between an element and a pure
substance?
• Provide an example of an element and a compound.
• Where would you find a list of elements?
Which is it?
Mixture
Element
Compound
Study Buddy Review
• What is a mixture?
• What is the difference between a homogeneous and
heterogeneous mixture?
• Provide an example of homogeneous and heterogeneous
mixture.
Physical and Chemical Properties
Properties of Matter
Physical Properties
Property of an object that can be observed or
measured without changing the substance
• Examples and values for water:
– Density
– Color
– Freezing Point
1 g / 1 mL or 1 g / cm3
colorless
0o C
Density
• Density is the mass per unit volume of a
substance
• D = mass / volume
– Measured in g / mL or g / cm3
• Less dense objects float on more dense
objects
• Density of liquid water is more than
density of ice (so ice floats in liquid water)
Significance of Physical
Properties
• Help to identify a substance
• Examples:
–Density
–Melting Point
–Boiling Point
Properties of Matter
Chemical Properties
Relates to a substance’s ability to undergo
changes that transform it into different
substances
• Examples :
– flammability
– Ability to rust
How do you know if chemical
reaction occurred?
• Chemical changes produce new, different
substances
–
–
–
–
Precipitate formed (solid)
Gas formed (bubbling)
Energy change occurs (colder or hotter)
Color change (can also be physical—be
careful!)
Significance of Chemical
Properties
• Chemical changes are chemical
reactions
• Examples:
–Combustion
–Oxidation
–neutralization
Extensive and Intensive
Properties
• Extensive: depend
on the amount of
matter that is
present
• Examples:
– Mass
– Volume
– energy
• Intensive: do NOT
depend on the
amount of matter
that is present
• Examples:
– Melting point
– Density
– temperature
Law of Conservation of Energy
• Law of Conservation of Energy: in all physical
and chemical changes, energy is neither created
or destroyed
• Energy: the capacity to do work or produce heat
• Measured in Joules (SI unit)
Law of Conservation of Matter
• Law of Conservation of Matter: in all chemical
and physical changes, matter is neither created or
destroyed
• A chemical change is a really chemical reaction
4 Fe + 3 O2  2 Fe2O3
Reactants  products
• Antoine Lavoisier:
– Made accurate and precise measurements
during chemical reactions
Study Buddy Review
Classify each as a physical or chemical
property of matter:
•
•
•
•
•
•
•
•
•
•
Blue Color
Ability to Rust
Density
Flammability
Reacts with a base to form water
Boiling Point
Reacts with water to form a gas
Luster
Mass
Odor