1. Intro moments
• Various students will research & share
– Date & key idea or finding
1.J.J. Thomson
2.Rutherford
3.Dalton
4.Proton, neutron, & electron (how discovered)
5.P+
, No
, e-
(how can you use the periodic table to determine these values)
2. WEBSITES
• www.tinyurl.com/mrkicker
– For assignments and downloading documents
you may want to print
• https://classroom.google.com
– For vocab and online forms (won’t need to
make copies) turn in online with button
• http://learn.kearneypublicschools.org/
– For blogs, practice tests, quizlets, etc.
• http://www.classzone.com/
– Our online book
4. Periodic Table
• Look at the values
on PT
• Larger # is mass
• Smaller (whole #)
is atomic #
5. What determines an Element
•Proton!– This is a positive charged sub atomic
particle
– The atomic number equals the # of P+
s
6. Strong force
• Protons don’t like each other so what
holds them together?
• Neutrons (these act like glue)
– No charge, about the same mass & size
of P+
– Mass of an atom is P+
s + No
s
7. Atoms are neutral
• There are electrons
that surround the
nucleus. The
number of P+
equals # of e-s
8.
9. Let’s try a couple …
• WS (all but last two)
• Ions are charged atoms. These are
different from atoms. Same P+
& No
, but
different number of e-
s
10. What does Kicker Mean?
• What determines the atom?
– What does this mean:
• What particle does the chemistry?
– Where are these particles located?
11. Determine the subatomic particles
• See page 65
• Determine subatomic particles for
• Ti
Make this symbolism for an atom / ion with 11 p+ 12 No and 11 e-
Make this symbolism for atom / ion with 52 p+ 75 No and 54 e-
92
235
U6
14
C Fe+3
12. What is a model?
–It is an idea or
representation of something
–It must act like what we are
talking about and is used to
predict things!
13. Atomic theory
Dalton (sphere)
Thomson (electron)
Rutherford (dense positive nucleus &
huge empty space)
Later we find the size of subatomic
particles & charges of them….
14. John Dalton (1766-1844)
• The idea of atoms had been proposed
much earlier. The ancient Greek
philosophers had talked about atoms,
but Dalton's theory was different in
that it had the weight of careful
chemical measurements behind it.
15. DALTON’S ATOMIC THEORY
1. All elements are composed of tiny indivisible
particles called atoms.
2. Atoms of the same element are identical. Atoms of
any one element are different from those of another
element. (hydrogen and helium, oxygen and nitrogen)
3. Atoms of different elements can physically mix
together or can chemically combine with one another
in simple whole number ratios to form compounds
4. Chemical reactions occur when atoms are separated,
joined, or rearranged. Atoms of one element however
are never changed into atoms of another element as
a result of a chemical reaction.
18. DALTON’S ATOMIC THEORY
3. Atoms of any one element
are different from those of
another element. (ex. hydrogen, oxygen
and nitrogen)
19. DALTON’S ATOMIC THEORY
4. atoms of different elements
can physically mix together or
can chemically combine with
one another in simple whole
number ratios to form
compounds
20. DALTON’S ATOMIC THEORY
5. Atoms are indivisible in a chemical
process. They can not be created nor
destroyed. Atoms of one element are
never changed into atoms of another
element as a result of a chemical
reaction. They are grouped together
differently.
21. John Dalton (early 1800’s)
• Said elements combined in the same
percentage by mass. In other words: Atoms
of different elements always combine in
fixed number ratios to produce specific
compounds.
• We know this as law of definite proportions
(or constant composition)
• Dalton’s Model - indivisible sphere with
uniform density throughout.
22. Sir William Crookes - 1870’s
• Put electrodes in a glass tube.
• Got a green “beam”
• Tested with magnet and the beam bent - it
contained PARTICLES!
• Further experimentation deduced that the beam
was negative in charge.
• Developed the cathode ray tube - ex...
24. Thomson’s model
and the cathode
ray tube
• Thomson’s experiments
provided the first evidence that
atoms are made of even
smaller particles.
25.
26. J.J. Thomson - 1897
• Set up CRT. Using magnets and
charged electric plates, was able to
determine:
– - the particles in the CRT always had the
same ratio of charge and mass regardless
of the gas used.
– The gas bent the same, regardless of
element
– - the particles were identical to each other
– Particles were subatomic and found in
all atoms.
27. J.J. Thomson - continued
• Thomson credited with discovering the first
type of subatomic particle - the electron
• Electron - negatively charged particle
found in atoms.
28. J.J. Thomson - some more
• Discovered a second beam, going the
opposite direction of the previous beam
• Charge equal, but opposite to the
electron.
• He revised Dalton’s model to his own
and called it the Plum Pudding model.
29. Summary
• Thomson’s second particle was a proton.
• Equal but opposite in charge to an electron
• 1836 times more massive than an electron
30. Rutherford
• Found evidence that the
atom has a small core, a
nucleus. Suggested that
the atom might resemble
a tiny solar system, with
a massive, positively
charged center circled by
only a few electrons.
31. Ernest Rutherford - 1909
• Used alpha particles (from radioactive
decay) to bombard targets made of sheets
of gold.
• Positive alpha particles, according to
Thomson’s model should have been
repelled evenly and go straight through.
• However, some were deflected.
32. Ernest Rutherford - continued
• Thomson’s Model didn’t explain
deflections
• Rutherford theorized that the atom
had a small dense nucleus with
99.9 % of the mass, and the
electrons hovered around that
nucleus in mostly an empty space
or cloud
33. READ THE CHAPTER
• Test
– On moodle: code 1
• Reading start book probs & vocabulary
• We’ll start here tomorrow
– Bring a key or something to plate (coin)
34. GRADES & TEST
• Blogs due ASAP
• STOP IN IF YOU DON’T GET IT
• READ THE CHAPTER
35. • OUTLINE NOTES AFTER THE POWERPOINT ( fill in the key ideas of the unit here)
• I. Dalton and the beginning of the Atomic Theory
• II. Thomsen’s Cathode Ray Tube Experiment
• III. The subatomic particles in the atom. * values on the periodic table tell us a lot WS
• IV. Rutherford’s Gold Foil Experiment * LAB
• V. Atoms and their ions. Cations and Anions * We DO WS
• VI. Isotopes, mass number, atomic number and charge.
36.
37. What do we know now?
• Protons +
• Neutrons 0
• Electrons -
• The atom is mostly empty space with electrons
taking up most of the volume and nucleus has
most of the mass.
Same size found in
nucleus
Very tiny (1/2000)
size of hydrogen.
38. ISOTOPES
• Are atoms of the same element that have
different numbers of neutrons. See pg 64
11
23
Na 11
21
Na
1
2
H 1
3
H
41. Ions
• Ions are charged atoms.
• If the proton determines the atom, what
would have to move in order for an atom to
become charged?
• How many p+, No & e-
• Li Li+1
• O O-2
42. See patterns on PT
• Tomorrow Cu Key Lab & packet work.
– pg 7-9 due tomorrow & PDPS
– Pg 10-11 due on Thurs along with book probs
– Online Vocabulary
– Everyone: check your grades!
45. ASSIGNMENT In Class
• Do Copper Key Lab Now
– Read handout & discuss what plating is
– Lab
– In groups do worksheets in packet and discuss
book probs.
• PDPs - TIME TO MAKE SOME
46. Last day
• Ions & charges
• Putting some elements together
– Simple binary
• Book probs: pg 86-89 , 45, 46, 52
• CH REVIEW SUMMARY WS packet pg
20-21
Notas do Editor
Can you think of examples of models that we use in science? Biology?
How about a car? Battleship? A bridge?
Today we will talk about 2 different models and you will see how the model will help lead to predictions that rutherford had.
First person to really examine atomic structure. He studied the ratios in which elements combine, conducted experiments, formed hypothesis and theories to explain his observations.
(these will follow larger) The book said 5, but we really can combine two of them to be these 4 things.
Tiny hard spheres, unbreakable. Can you think of something that is like this for a model? A billiard ball?
All carbon atoms have the same chemical and physical properties. It is also different than sulfur. (today this seems like a given, but back then it wasn’t)
All carbon atoms have the same chemical and physical properties. It is also different than sulfur. (today this seems like a given, but back then it wasn’t)
We know this as law of definite proportions.
Atoms can combine to make molecules in whole number ratios. (see pg 107 for a diagram)
Lead can not turn into gold by a chemical reaction.
Conservation of mass: All atoms present at the beginning of a reaction are present at the end
He did a lot more than Dalton and actually proved that the atom was divisible into smaller parts. Remember that Before his time, scientists thought that the atom was solid ball of matter.
Thomson passed electric current through gasses at low pressure. He sealed the He passed electricity through a sealed tube full of different gasses at low pressure. The electricity went from the positive (anode) to the negative plate (cathode) it gave off a glow. This glow was called the cathode ray. He found that the cathode ray was attracted to the plates and that negative electrical charge repels the ray. WHAT DID THIS PROVE?
(SEE PG 109 & 110 IN TEXT FOR MORE)
What has been proven wrong with dalton’s original theory?
Atoms are not indivisible.
Later we’ll find out that the discovery of isotopes contradicts dalton’s theory too.
SO WHAT DOES THIS MODEL LOOK LIKE NOW?
He came up with the “plum pudding” model. Let’s draw that plumb model
