Transcript matter

P. Sci.
Unit 7
Chapter 2
Matter
Chemistry
• What things are made of and
how things change.
Matter
• Has mass and takes up space.
• Matter is made up of atoms
• Light sound and electricity are
NOT matter
• Why?
Atoms
The smallest particle that
has the properties of
an element.
Element – a substance that cannot
be broken down into simpler
substances.
All the atoms in the substance are alike
Elements
• Each element has a one or two
letter symbol used worldwide to
designate it.
• The chart that shows
all the known elements
is called the Periodic
Table of Elements.
Compounds
• When two or more elements
combine chemically you get a
compound.
Molecule
• The smallest unit of a substance
that exhibits all the properties of
that substance.
Chemical formulas
• The combination of chemical
symbols (and how many atoms of
each) make up a molecule of a
substance.
Pure Substance vs.
Mixtures
• Pure substances – any
substance that has a fixed
composition and definite
properties.
Table sugar - C12H22O11
Hydrogen - H
• Mixtures - A combination of
substances that are not fixed;
they can change
OJ – is a mixture of water, citric
acid and sugar among other
things. Any drop of Orange Juice
can have different amounts of
the different components.
Air – CO2, N2, O2
Classifications of Mixtures
• Homogeneous Mixtures – a
mixture that is the same
throughout (completely
mixed)
• Heterogeneous Mixtures –
a mixture where you can
see all the parts.
(incompletely mixed)
Classification of Matter
MATTER
Pure
Substance
Mixture
Elements
Compounds
Heterogenous
Homogeneous
Carbon, gold, iron
NaCl, H2O
Salad, sand and water
Sandwich, pizza
Coke, iced tea,
Kool-aid
Properties of Matter
• Physical Properties
• Chemical Properties
Changes of Matter
• Physical Changes
• Chemical Changes
Physical Properties
• characteristics of
a material which
can be observed
without changing
the identity of the
substances in
the material.
Ex. include color,
shape, size, melting
point, and boiling point,
density
Physical Properties
• Appearance – physical description of a
substance.
• Behavior – how a substance acts; for
example, magnetism, viscosity, ductility.
• Physical properties such as size and
magnetism can be used to separate
mixtures.
Density
• The mass per unit volume of
a substance.
(how much matter is packed into a
specific amount of a substance)
• d = m/v
• Density is a physical
property.
Physical Change
• A change in a
• Examples:
substance’s
change in size,
physical property
shape, or state
(properties).
of matter.
• Substance does
not change
identity when it
undergoes a
physical change.
Physical Change:
Change of State
• When a substance
goes from one
state of matter to
another the
substance does
not change into
another substance.
(ice, water, steam
– are all H2O)
• Therefore –
Change of State
is a Physical
Change.
Example: melting,
boiling, freezing,
condensation,
sublimation,
evaporation, etc.
Physical Change:
Dissolving
• When a substance dissolves, it
seems to disappear because the
particles of the substance spread
out between the particles of the
liquid. Neither substance
changes into another substance,
therefore:
• Dissolving is a physical change.
Chemical Properties
• Characteristics
of a substance
indicating that
it can change
chemically.
• Examples:
flammability or
light sensitivity of
a substance,
production of a
gas, production
of a precipitate,
change in odor.
Chemical Change
• When one substance
changes to another
substance.
• Some chemical changes
are indicated by
temperature change,
smell, or bubble
formation.
• Other chemical changes occur
very slowly such as the
formation of rust.