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Atomic History and
Atomic Structure
8TH GRADE SCIENCE
Do Now Monday
th
October 17
Classify each element as a metal, nonmetal, or metalloid.
a) Arsenic (As)
b) Xenon (Xe)
c) Aluminum (Al)
d) An element that is malleable, ductile, and a good
conductor of heat and electricity
e) An element that is a a dull solid that is brittle
f) An element that is shiny and is a semi-conductor.
TODAY’S PLAN
• Identify 6 scientists who contributed to our
knowledge of the structure of the atom.
• Explain the structure of the atom.
• Differentiate between the subatomic particles of an
atom: protons, neutrons, and electrons;
TODAY’S DO
• Complete a WebQuest about Atomic History and
Atomic Scientists (Independently and Quietly)
Do Now Tuesday
th
October 18
1.What are the properties of metals?
2.What are the properties of
metalloids?
3.What are the properties of
nonmetals?
TODAY’S PLAN
•
•
•
•
•
Identify 6 scientists who contributed to our knowledge
of the structure of the atom.
Explain the structure of the atom.
Differentiate between the subatomic particles of an
atom: protons, neutrons, and electrons.
Discuss what the atomic number represents concerning
the atoms of an element.
Discuss what the mass number represents concerning
the atoms of an element.
TODAY’S DO
•
•
•
Quiz
Briefly review scientists and atomic structure
Calculate the number of protons, neutrons, and
electrons in atoms of an element.
Atomic Theory
Changes over time…
Atomic Theory
Because we can not see atoms, we use models to teach and learn
about atoms.
The atomic theory has changed over time as new technologies have
become available.
◦ Remember: Scientific knowledge builds on past research and experimentation.
On Page 40
Make a list of these names. Skip a line or two
between each one so you can write a brief
statement about each.
1.
2.
3.
4.
5.
6.
Democritus
Dalton
JJ Thomson
Rutherford
Bohr
Schrodinger
AtomicTheory
TheoryTimeline
Timeline
Atomic
Scientist
Information
Democritus
(400 BC)
• Named atoms “atomos”
• Said everything is composed
of atoms.
• Atoms are indestructible.
• Between atoms lies empty
space.
• There is an infinite number
and kinds of atoms.
Model
Atomic Theory Timeline
Scientist
John Dalton
(2000 years
after
Democritus)
Information
• All matter is made of atoms.
• Atoms are too small to see,
indivisible and indestructible.
• All atoms of a given element
are identical.
Model
Atomic
Timeline
Atomic Theory
Theory Timeline
Scientist
J.J.
Thomson
Information
• Discovered the negative
electron, using the cathode ray
tube
• Plum Pudding model
Model
Atomic
Timeline
Atomic Theory
Theory Timeline
Scientist
Ernest
Rutherford
Information
• Atoms are mostly empty space
• Discovered tiny, positively charged
NUCLEUS using the gold-foil
experiment
• Name positive charged particle
“proton”
Model
Atomic Theory Timeline
Scientist
Information
Neils Bohr Concluded that electrons are
located in neat planet-like orbits
around the nucleus in certain
energy levels
Model
Scientist
Schrodinger
(and many
others):
Modern
Atomic
Theory
Information
• Electrons do not orbit the
nucleus in neat planet-like
orbits but move at high speeds
in an electron cloud around the
nucleus.
• We can not know the exact
location of an electron.
Model
Atomic Structure
Copy this table into your journal.
Subatomic
Particle
Mass (amu)
Charge
Location
Proton (p+)
1
+1
nucleus
Neutron (no)
1
0
nucleus
Electron (e-)
0
-1
Rings (energy
levels) outside
nucleus
Atomic Structure
Atomic Number and Mass
Number
Atomic Number
◦ Identifies the element
◦ Is the number of protons
◦ In a neutral atom, is also
the number of electrons
Mass number when rounded
Mass Number
◦ Decimal number rounded to nearest whole number
◦ Includes both protons and neutrons
◦ Mass number = p+ + no
◦ So, no = mass number – p+
Calculating protons, neutrons, electrons
p+ = atomic # = 1
e- = p+ = 1
no = mass # - atomic # = 1-1 = 0
Calculating protons, neutrons, electrons
p+ = atomic # = 2
e- = p+ = 2
no = mass # - atomic # = 4-2 = 2
Calculating protons, neutrons, electrons
p+ = atomic # = 3
e- = p+ = 3
no = mass # - atomic # = 7-3 = 4
Do Now Wednesday
th
October 18
Answer the questions on the sheet given to you.
Blood Types of 100 Donors
TODAY’S PLAN
•
Determine the electronic structure for elements 1-20 on
the Periodic Table.
• TODAY’S DO
•
•
•
Check Homework
Review calculating the number of protons, neutrons,
and electrons.
Draw the electronic structure of elements.
Element
Hydrogen
Helium
Lithium
Beryllium
Carbon
Nitrogen
Oxygen
Fluorine
Sodium
Symbol
p+
e-
n0
1st
energy
level
2nd
energy
level
3rd
energy
level
4th
energy
level
Element
Magnesium
Aluminum
Silicon
Phosphorus
Chlorine
Argon
Potassium
Calcium
Symbol
p+
e-
n0
1st
energy
level
2nd
energy
level
3rd
energy
level
4th
energy
level
Electronic Structure
E1 = 2 electrons
E2 = 8 electrons
E3 = 8 electrons
E4 = 8 electrons
Electronic Structure Example
Electronic Structure Example
Electronic Structure example
Do Now Friday
th
October 20
TURN IN YOUR HOMEWORK SHEET FROM WEDNESDAY IN
THE BLACK BASKET.
Pick up from the front table and answer the questions on
the sheet given to you.
Once you have finished, raise your hand so I can check
your work.
Only when you have shown me that you know how to do
the work will you be allowed to construct your model of an
atom.
TODAY’S PLAN
•
•
•
•
Explain the structure of the atom.
Discuss what the atomic number represents concerning
the atoms of an element.
Discuss what the mass number represents concerning
the atoms of an element.
Determine the electronic structure for elements 1-20 on
the Periodic Table.
TODAY’S DO
•
Create Bohr Model of an atom of an assigned element
Do Now Tuesday
th
October 25
Draw and complete the table.
Atomic
Symbol
Atomic
Number
Protons
Neutrons
Electrons
Al
6
Draw the electronic structure for Al.
Mass
Number
TODAY’S PLAN
•
•
•
Create a Bohr Model of an atom.
Discuss what the atomic number represents concerning
the atoms of an element.
Discuss what the mass number represents concerning
the atoms of an element.
TODAY’S DO
•
•
•
•
Create/Finish your Bohr Model of an atom of an assigned
element
When finished with your atom model, pick up a puzzle
sheet from the table in the front of the room and practice
calculating protons, neutrons, and electrons for elements.
Color your sheet (with pencil) as directed to solve the
puzzle.
Calculating p+, n0, e- QUIZ TOMORROW, Wednesday,
October 26th!!
Bohr Atomic model
Beads: electrons, protons, and neutrons (3 different colors)
Pipe cleaners: energy levels
1. Make a nucleus by stringing the correct number and color
of beads onto 1 pipe cleaner. The smash it into a little ball.
2. Make the appropriate number of energy levels by using 1
(for smaller energy levels) or 2 (larger energy levels) pipe
cleaners with the correct color and number of beads for
each energy level.
3. Connect the nucleus and each energy level by attaching
strings between each so that all can spin freely. (Nucleus
and energy levels should not touch.)
4. Attach the card for your element to the bottom of your
model and hang from a cabinet or the line in the back of
the room.