Download Atoms {PowerPoint}

Science Module
th
8
Grade
TAKS Objective 3
The student will demonstrate an
understanding of the structure and
properties of matter.
TEKS 8.8 A and B
The student knows that matter is composed
of atoms. The student is expected to:
A. describe the structure and parts of an
atom; and
B. identify the properties of an atom
including mass and electrical charge.
Objectives
•
•
The learner will be able to describe the parts
of an atom.
The learner will be able to compare mass
and charges of the electron, proton, and
neutron.
Lesson Objectives
“Continued”
• The learner will use appropriate models
and analogies to describe the size of an
atom and its particles.
• The learner will explain the development
of the atomic theory.
Misconceptions
True or False
Electrons are little spheres
that orbit the nucleus of an atom
Electrons have no known shape and almost
no mass. They do not orbit; they move
randomly in an electron cloud.
True or False
Atoms are like miniature solar systems
The only thing an atom and the solar system
have in common, is both are mostly empty
space.
True or False
The electron is the same size
as a proton or neutron
The electron has no size and practically no
mass compared to a proton or a neutron.
Background
Development of
Atomic Theory
440 BC - Democritus
first suggested the
existence of atoms
1803 - John Dalton
suggested a 3-part
atomic theory (1)
everything is made of
atoms (2) atoms
combine to make new
substances (3) atoms
of the same element
are alike
1897 – J.J. Thomson proposed the plum
pudding model of the atom. Atoms are
mostly positive with negative particles.
1909 – Rutherford conducted his famous gold foil
experiment discovering that atoms were mostly
empty space with a dense positive center.
1913 – Bohr describes the orbit of atoms as
traveling around the nucleus in definite
orbits (planetary model).
1914 – Moseley
used the cathode
rays to determine
the number of
positive charges in
the nucleus (first
concept of atomic
number).
1926 – Schrodinger
developed quantum
theory to describe the
behavior of subatomic
particles.
TEGS: The Atom
Quantum Atom
1932 – Chadwick
won the Nobel
Prize for his
discovery of the
neutron.
A Tiny Big Discovery
Engage
Cut a piece of paper in half as many times
as you can.
1
2
3 4
Explore
The “Black” box activity is important on
several levels:
•
•
•
Students explore studying things they
cannot see or directly touch.
Students share information with others to
expand and check results.
Students learn that scientists cannot
check for the right answer (Keep the box
closed and never reveal what is inside!)
Explore
Who knew? is an activity designed to help
students understand how science is built
upon the investigations of previous scientists
and determined in large part by the
technology available.
Explain
The atom is composed of mostly empty space.
Atom Field video
http://www.tcet.unt.edu/tegs/chapter3/Atomic%20field_Medium.mov
electron
neutron
proton
This animation shows the Scanning
Tunneling Microscope (STM) mapping
atomic clouds in the silicon material. The
STM uses a needle with a single atom on
the tip to “see” the silicon atoms by their
charged electron clouds.
STM Animation
http://www.tcet.unt.edu/tegs/chapter3/STM%20Animation.ppt
Electrons are very small compared to a
proton.
If the proton were the mass of an
automobile, the electron would have the
mass of a bag of potato chips.
Elaborate
• Particle Play
• Stripping Electrons
• On the Shoulders of Giants
Evaluate
Allow students to choose a particle and write
an illustrated “biography.” Include the
particle’s discovery, charge, and location in
the atom.