Download DEFINING THE ATOM

Drill

Calculate the the following:


Mass = 39.2g; Vol = 27.2 mL; Density = ?
Mass = 39 g; Density = 1g/mL; Volume =?
Objective

SWBAT: Diagram the historical
development of the atom in order to
compare and contrast each model’s
advantages/ limitations.
SAT/HSA Enrichment

How many kilograms are equivalent to
345 grams?
WEB Organizer:

To assess students’ prior knowledge
about the current theory describing the
model of the atom.
Defining the Atom
What is the Atom?
Defining the Atom

The lab technician
shown here is using a
magnifying lens to
examine a bacterial
culture in a petri dish.
When scientists cannot
see the details of what
they study, they try to
obtain experimental
data that help fill in
the picture.
Early Models of the Atom

An atom is the smallest particle of
an element that retains its identity
in a chemical reaction.

Philosophers and scientists have proposed
many ideas on the structure of atoms.
Early Models of the Atom


Democritus’s Atomic Philosophy
Democritus believed that atoms were
indivisible and indestructible.

Democritus’s ideas were limited because they didn’t
explain chemical behavior and they lacked
experimental support.
Early Models of the Atom

Dalton’s Atomic Theory

By using experimental methods, Dalton
transformed Democritus’s ideas on
atoms into a scientific theory.

The result was Dalton’s atomic theory.
Early Models of the Atom

All elements
are composed
of tiny
indivisible
particles called
atoms.
Early Models of the Atom

Atoms of the
same element
are identical.
The atoms of
any one
element are
different from
those of any
other element.
Early Models of the Atom

Atoms of
different
elements can
physically mix
together or can
chemically
combine in
simple wholenumber ratios to
form
compounds.
Early Models of the Atom

Chemical reactions
occur when atoms
are separated, joined,
or rearranged. Atoms
of one element are
never changed into
atoms of another
element in a chemical
reaction.
Sizing up the Atom

Despite their small size, individual
atoms are observable with
instruments such as scanning
tunneling microscopes.
Iron Atoms Seen
Through a Scanning
Tunneling
Microscope
Short Quiz
1. The ancient Greek philosopher credited
with suggesting all matter is made of
indivisible atoms is
a.
b.
c.
d.
Plato.
Aristotle.
Democritus.
Socrates.
Short Quiz
2. Dalton's atomic theory improved earlier
atomic theory by
a.
b.
c.
d.
teaching that all matter is composed of tiny
particles called atoms.
theorizing that all atoms of the same element
are identical.
using experimental methods to establish a
scientific theory.
not relating atoms to chemical change.
Short Quiz
3.
Individual atoms are observable with
a.
b.
c.
d.
the naked eye.
a magnifying glass.
a light microscope.
a scanning tunneling microscope.
The Atomic Structure

Groups:
 Each group will have one person
for each atomic theory.
Groups: (20 min)

Groups:
 Responsible for completing the
information for their atomic theory on
the Atomic theory worksheet.
 Responsible for drawing a model of
their atom from their atomic theory.
Groups:

Groups:
 Responsible for sharing
information that was gathered
about all the atomic theories to
the class, as well as draw an
illustration of the atom to go with
their findings.
Illustrations: (10 min)

Students will observe all of the
illustrations that were created in
each group.
 Discuss the distinguishing
features and
advantages/limitation of each
atomic model.
Analysis/Summary Questions

Complete the Summary questions.
(10 min)
Summary
1.
2.
3.
4.
5.
How did Democritus characterize atoms?
How did Dalton advance the atomic
philosophy proposed by Democritus?
What instrument can be used to observe
individual atoms?
In your own words, state the main ideas of
Dalton’s atomic theory.
According to Dalton’s atomic theory, is it
impossible to convert atoms of one element
into atoms of another? Explain.
Exit ticket:

Complete Atomic Structure worksheet.

Homework:

Complete Atomic Theory Homework