Particles of Matter
EQ: How do I describe the
smallest particles of an element?
Atoms
• The smallest particle of an element
EQ: How do I describe the
smallest particles of an
element?
Democritus
• A Greek
• First to suggest that
matter could be
divided into pieces
and that there is a
time when they
cannot be cut any
further
• Called the smallest
pieces atomos which
is Greek for
“uncuttable”
EQ: How do I describe the
smallest particles of an
element?
Dalton
• A teacher from 1802
• Proposed the atomic
theory
• His theory has five
components
EQ: How do I describe the
smallest particles of an
element?
Dalton’s Ideas
• Atoms can’t be broken into smaller pieces.
– He imagined them as tiny marbles, impossible
to break
• In any element, all atoms are exactly alike.
An element always has the same
properties
EQ: How do I describe the smallest
particles of an element?
Dalton’s Ideas
EQ: How do I describe the smallest
particles of an element?
• Atoms of two or
more elements can
combine to form a
compound
• Atoms of each
element have a
unique mass – still
have not been able
to measure the mass
of individual atoms
Dalton’s ideas
• The masses of the elements in a
compound are always in constant ratio
EQ: How
do I
describe
the
smallest
particles
of an
element?
Atoms and Molecules Today
• Molecule – a group of atoms that are
joined together act like a single unit
• Chemical bond – the force that holds two
atoms together
EQ: How do I describe the
smallest particles of an
element?
How small are atoms?
• One sheet of paper is 10,000 atoms thick
• So small only a scanning tunneling
microscope can capture the image
EQ: How do I describe the
smallest particles of an
element?
a device that "feels" the
cloud of electrons that
form the outer surface of
atoms, rather as a
phonograph needle feels
the grooves in a record.
Particle Model
• The way we explain matter in terms of
atoms and molecules
http://www.mcgrawhill.ca/school/applets/bcscience7/particle/index.htm
EQ: How do I describe the smallest particles
of an element?
Class Work and Homework
• Fill In
– What did I learn
– Confused
– Say
EQ: How do I
describe the
smallest particles
of an element?
– Read Particles of Matter in the folder
– Answer questions 1 – 5, p. K 33