Download ATOMIC THEORY AND STRUCTURE

ATOMS (notes)
• What are atoms?
Atoms are the smallest unit of an element; it is the
building block of matter. Atoms have the chemical
properties of that element.
Let’s review:
What is a chemical property of iron? (Iron is an
element)
- It can rust when it comes in contact with oxygen
and water
According to our definition, this means that an
atom of iron has the ability to rust.
Today, we know atoms exist…
Today we can put anything under a
microscope and see that they are made up
of atoms…so we have evidence that atoms
exist!!!!
Salt under a
microscope!!!!
Limestone!!!
Limestone under
a microscope!!!!
Diamond!!!
Diamond under
a microscope!!!!
How did scientists know atoms
existed back in the day when they
did not have such technology and
couldn’t see them?
1. Observed
2. Scientific Question – when you keep cutting a piece of
cheese in half forever, what will you be left with?
3. Hypothesis – If cheese is cut forever, then smaller pieces
of cheese will be created until cheese can’t be cut anymore
.
5. Conduct an experiment
6. Collect and analyze data
7. Draw a conclusion
BUILD ON OTHER SCIENTISTS’ WORK
DO NOW
1. Pick up SCIENCE FAIR 2013 handout
from DO NOW FOLDER.
Answer the following questions in you
notebook.
1. Summarize Thomson’s experiment.
What did he discover?
2. Summarize Rutherford’s experiment.
What did he discover?
3 THING THAT NEED TO BE OUT ON
YOUR DESK ARE…
HOMEWORK IS DUE TODAY!!
Make sure to leave it in your
period’s TURN IN box before you
leave class.
SCIENTISTS IN HISTORY:
ATOMIC THEORY
VOCAB:
ATOMIC THEORY: an idea of what the atom is, what it is made
of, and what it looks like.
What does “idea” mean to you?
Is an idea based on evidence?
John Dalton
• 1766
• Dalton’s Atomic Theory:
1. All elements are made up of atoms
2. Atoms of one elements are the same; atoms of different
elements are different
3. Compounds are made up of atom of different elements
4. Ratio of elements in a compound are the same
Dalton did
experiments and
had evidence:
splitting water
molecules
J. J. Thomson
Cathode Ray Tube Experiment
J.J. Thomson
• 1897
• This was the first evidence that atoms are made of smaller,
negatively charged particles. He called these particles electrons.
• Thomson knew that an atom was neutral (has no charge).
How can atom contain negative particles and still be neutral?
- There must be positive charges to cancel out the negative charge
How did J.J. Thomson disprove Dalton’s atomic theory?
• Disproved Dalton theory by showing atom can be divided into
positive and negative particles.
• Atomic theory: The negatively charged particles are evenly
scattered or spread in positively charged atom.
• Name of atomic theory model: Plum pudding model
Ernest Rutherford
Gold Foil Experiment
Ernest Rutherford
• 1909
How can positive charge repel?
- When positive charge comes near another positive charge
• Evidence: The positive light is hitting something dense and
positive within the atom for the light to be repelled and bounced
back
• Rutherford’s atomic model: all of an atoms positive charge is
concentrated at its center or the nucleus.
-Positively charged particle in that atom became known as
protons.
• Atomic theory: Electrons are found around the nucleus that
contains the protons. Between the electrons and the nucleus was
empty space.
• Atomic model name: Solar system model
SCIENTISTS IN HISTORY:
ATOMIC THEORY
You will be in divided into 6 groups and will be assigned a
scientist who contributed to the atomic theory
YOUR GOAL: As a group, you’ll use your notes to pull out
important information about the scientist and fill out the
table on the handout. After you get the table checked off
by me, you and your group will make a poster for your
scientist to go in a science magazine to headline his
discovery and contribution.
POSTER CONTEST?
GALLERY WALK
Now that everybody’s posters are up, as a group you
are going to stop by the other posters and get the
same information for the other scientists.
MUST TURN IN: you groups’ table that I check of on as
well as completed table for all scientists.