Download Electron - My CCSD

BELL WORK: TUESDAY 2/7/12
On the front table there is a
stack of papers titled “Mercury:
Mysterious and Deadly”.
Get one of these papers
It is an article that you will read
silently
There are 7 questions you will
answer by yourself on the back.
On your Bell Work for “Tuesday”
you need to write “ARTICLE”
MERCURY: MYSTERIOUS AND DEADLY
QUESTIONS
 How did Mercury get the nickname “quicksilver”?
 What did alchemists struggle to make using mercury and sulfur?
 Many people over time were found to have health problems.
What was eventually found to be the cause of it?
 What type of ef fects happen to people surrounded by mercury?
 High School Chemistry Story
 Why is vacuuming a mercury spill not the best way to clean up a
mercury spill?
 Middle School Story
 What does this article have to do with
Chemistry?
 Why would your teacher have you read
an article like this?
…describe the atom as the basic
building block of matter
…identify substances based on
their physical and chemical
properties
…identify the bonds that hold
atoms together and
describe properties
associated with these bonds
…describe how the
elements are arranged
on the Periodic Table of
Elements
…sort elements based on their
physical & chemical properties
…separate mixtures
into their basic
components
Questions to Consider:
What do you hope to
accomplish
throughout the
upcoming Chemistry
unit?
What goals do you
have for the rest of
the 2 nd semester?
What long-term
goals do you have
for science?
WHAT IS AN ATOM?- PAGE 1
Atom- basic
building block of
all matter
 All substances are
made up of matter
 Smallest particle of an
element that has the
properties of that
element
 5.1 - TSW explain that
matter is composed of
tiny particles called
atoms.
STRUCTURE OF
AN ATOM
Nucleus- tiny, central core of an atom
Contains protons (positively-charged)
Containing neutrons (with no/neutral charge)
Electrons move around the nucleus in
electron cloud
BELLWORK: WEDNESDAY 2/8/12
Get a book off the front table and the pink
packet.
Begin working on page 1 – the Nature of
Science Vocab.
Be sure to have the definition of each word
written down
You will only be given 10 minutes to work on
this.
Whatever is not finished today will be done as
homework.
Electron- negatively
charged; located outside
of the nucleus; negligible
mass (very small)
revolve
Subatomic Particles- Electrons
around nucleus in
particles that make
imaginary paths called
up an atom
orbits or shells
Proton- positively
Valence electronscharged; located in
electrons that are the
nucleus
farthest away from the
Neutron- neutrally
nucleus (in the outside
charged; located in
shell)
nucleus
THE ROLE OF ELECTRONS
Electrons…
 …move around the nucleus very fast
 …have a HUGE space to move around in
 …are different distances from the
nucleus
 …form a negatively charged cloud
around the nucleus
 …travel in paths called orbitals
 …cannot be exactly located at a
particular moment- probably do
(probability)
 Imagine the blades of a moving
fan…where are they exactly?
D
FILL IN THESE ON
PAGE 1
 Fill in the picture on
page 1 with the
appropriate subatomic
particle names, charges,
and locations in the
atom.
A
C
B
A
B
C
D
Subatomic
Particle
Proton
Neutron
Electron
Valence Electron
Charge
Positive (+)
Neutral (0)
Negative (-)
Negative (-)
Location in
atom
Inside
nucleus
Inside
nucleus
Outside
nucleus
Outside nucleus; outer
“valence” shell
LITTLE PARTICLES, BIG SPACES
Imagine standing at the pitcher’s mound in a
baseball stadium.
If the nucleus were the size of a pencil eraser, the
electrons could be in the outfield or the top row of
seats!
ATOMIC NUMBER
Atomic Number- the
unique number of
protons in a nucleus
# of (+) protons = #
of (-) electrons
Atoms are neutrally
charged (not
positive or negative)
Ex: Every Carbon
atom has 6 protons
How many
electrons in a
Carbon atom?
6 (# of (+) protons
= # of (-) electrons)
Atomic Mass- the average mass of one
atom of an element; protons + neutrons
Atomic mass units (amu)- unit for measuring very
small mass of subatomic particles
Proton mass = 1 amu
Neutron mass = 1 amu
Electron mass = 1/2000 amu
 ~2000 electrons = 1 amu
Most of an atom’s mass is in its nucleus
CHECK YOUR
UNDERSTANDING
Gold, Au, has an atomic
number of 79
 How many protons?
 79
 How many electrons?
 79
Gold, Au, has an atomic
At your party you need 10 pizzas to
mass of 196.97
 How many neutrons?
 196.97 – 79 = 117.97
 How many amu’s
 79 + 117.97 = 196.97
feed everyone. You buy 6 pizzas. How
many pizzas must other people provide
if you are going to have 10 total?
The total # of pizzas is like the atomic
mass. Protons bring some of the mass,
and neutrons bring the rest. Electrons
don’t really bring anything!!!
WHAT IS AN ELEMENT?
Element- Substance made
up of one kind of atom
Cannot be broken down into
other substances by chemical
and physical means
All listed in the Periodic Table
~82 naturally-occurring
elements
~31 synthetically prepared
(artificially-made) elements
Germanium
Sulfur
Mercury
“Element” = Carrot
 Imagine chopping a carrot
into smaller and smaller
pieces.
 You would eventually reach
a point where you could not
cut anymore because the
pieces were so small.
 But, those small pieces still
have the properties of the
larger carrot (taste, color,
etc.).
Element = Aluminum
 Imagine cutting Aluminum
(Al) into smaller and
smaller pieces.
 When you can no longer
divide it, they are Al atoms.
 But, they still have the
properties of Aluminum
(shiny, silver color, fragile,
thin, etc.)
MOLECULES VS. COMPOUNDS
When atoms bond together, they form:
Molecule – a combination of 2 or more of
the same or different atoms that are
bonded together
 Ex: H 2 O, NaCl, H 2 , O 2 , O 3 , N 2
 Diatomic Molecule- made of two of the same atoms
 Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, Bromine
 H2 O2 F2 Br2 I2 N2 Cl2

HOFBrINCl twins; I Have No Bright Or Clever Friends;
Hydrogen; the rest form a 7 on the periodic table: N, O, F
across, then going down Cl, Br, I
Compound – a molecule that contains
atoms or molecules of two or more
different elements
 Ex: H 2 O, C 6 H 12 O 6 , CH 4
BELLWORK:
THURSDAY
2/9/2012
Fill
these in
on page
1
 Fill in the following chart
with the appropriate
subatomic particle
names, charges, and
locations in the atom.
D
A
C
B
A
B
C
D
Subatomic
Particle
Proton
Neutron
Electron
Valence Electron
Charge
Positive (+)
Neutral (0)
Negative (-)
Negative (-)
Location in
atom
Inside
nucleus
Inside
nucleus
Outside
nucleus
Outside nucleus; outer
“valence” shell
WHAT IS A THEORY AND HOW DO YOU
MAKE ONE?
 Hypothesis – an educated guess, based on observation
 Theory – summarizes a hypothesis or group of hypotheses that
have been supported with repeated testing. This answers the
question of “why”
 This is valid as long as there is not evidence to dispute it.
 Law – generalizes a body of observations. At the time it is
made, no exceptions have been found. These explain things, but
do not describe them. Does not answer “why”
 For a theory to become a law it must…
 Not have any evidence to disprove it
 Have a hypothesis that has been testing many different ways and times
EVOLUTION OF THE ATOMIC THEORY
PGS 2 & 3
Read the passages provided, and
answer the questions about each
scientist and their experiments.
EVOLUTION OF THE ATOMIC THEORYPG 3
John Dalton
1. Atomic Theory of
Matter
2. Atoms
3. Different
4. Atoms of
different
elements
5. 1:1
J.J. Thomson
1. The electron
2. Negative
3. Negatively charged
electrons
4. Opposite charges
attract each other
5. Gas discharge
tubes
EVOLUTION OF THE ATOMIC THEORYPG 4
Lord Ernest Rutherford
1. Positive
2. He was shooting alpha
particles through a gold
foil sheet
3. Most particles passed
straight through the
foil.
4. Some got deflected
back, others went
through.
5. Positive repels positive
(positive nucleus repels
positive alpha particles)
Niels Bohr
1. The electrons go
around the nucleus
like planets around
the sun.
2. They are in different
energy levels;
different distances
from the nucleus
3. 32 electrons
4. Higher level =
absorb/gain energy
5. Release (lose)
EVOLUTION OF THE ATOMIC
MODEL
John Dalton
(1802)
Niels Bohr
(1913)
J.J. Thomson Ernest Rutherford
(1897)
(1911)
Erwin
Schrödinger
& Louis de
Broglie
(1920’s - present)
DEMOCRITUS (~400 BC)
Who was he?
A Greek philosopher
Discovery:
Matter can be cut into small
pieces
The smallest piece cannot be
broken down anymore = an atom
“Atomos” – Greek for uncuttable
Everything is composed of atoms
Atoms are always in motion
Model: The atom is a small,
solid sphere
JOHN DALTON (1802)
 Who was he?
 British schoolteacher, meteorologist
 Experiment:
 Studied the atmosphere and the
behavior of gases; he found they
always combined in predictable ways.
 Discovery (1802):
 Each element is made up of atoms
 Atoms of the same element are the
same.
 Atoms of different elements are
different
 “Billiard Ball Model” (Pool Ball):
 The atom is a small, solid sphere
BELLWORK: FRIDAY 2/10/2012
1. Where is the majority of an
atom’s mass?
2. What subatomic particles
compose the majority of an
atom’s mass?
3. Tricky: What composes the
majority of an atom’s
volume?
4. Beryllium’s atomic number
is 4, and its atomic mass is
9.01. How many protons,
neutrons, and electrons are
in one Beryllium atom?
1. Nucleus
2. Protons & Neutrons
3. Nothingness! Empty
space around the
nucleus
99.9% of matter is
actually empty space!
4. 4 protons,
5 neutrons,
4 electrons,
EVOLUTION OF THE ATOMIC
MODEL
John Dalton
(1802)
Niels Bohr
(1913)
J.J. Thomson Ernest Rutherford
(1897)
(1911)
Erwin
Schrödinger
& Louis de
Broglie
(1920’s - present)
J.J. THOMSON (1897)
 Who was he?
 A British scientist
 Experiment:
 Using a gas-discharge/cathode ray tube, he passed an electric current
through a vacuum tube
 Saw a stream of glowing material!!
 Discovered that mysterious glowing
stream would bend toward a positively
charged electric plate
 The stream was made up of small
particles that carried a negative
charge-- electrons .
Discovery (~1897):
The negatively charged electron
2000 electrons = the mass of
one proton
The “Plum-Pudding Model”:
Atoms are spheres filled with a
positively charged fluid;
electrons are scattered
throughout
Fluid = “pudding”; electrons =
“plums”
LORD ERNEST RUTHERFORD
(1909-1911)
 Who was he?
 New Zealand physicist
• Experiment:
“The Gold-Foil Experiment”
• Fired positively charged
particles (called alpha particles) at
a thin sheet of gold foil
• Most particles went through,
some bounced back, some were
deflected
Discovery
(1909-
1911) :
 Atom is mostly empty space
 Positively charged nucleus in
the center of the atom
 positive repels positive
The “Planetary Model”:
 Dense, small, positively
charged nucleus
 Surrounded by freely moving
electrons
NIELS BOHR (1913)
 Who is he?
 A Danish physicist
 Experiment:
Known:
Elements possess specific amounts of energy
Light was given out when they were heated, but no one
could explain why
Bohr looked at line spectra (colored lines of light),
which show energy being emitted.
Energy was released when electrons moved from
one shell to another
Bohr suggested the electrons must orbit nucleus in
fixed energy levels (or electron shells)
Discovery (1913):
 Electrons move in fixed orbits
around the nucleus (electron
shells)
 Electrons exist in energy levels
 Atoms absorb or give off energy
when electrons move from one
shell (energy level) to another
The “Bohr Model”:
 An electron's energy levels ( also
called electron shells ) can be
imagined as concentric circles
around the nucleus
ERWIN SCHRÖDINGER & LOUIS DE BROGLIE
(1925 THROUGH PRESENT)
Who were they?
 Louis de Broglie was a French scientist
 Erwin Schrodinger was a Austrian physicist
Experiment/Observation:
 It is impossible to know the speed and exact location of an
electron
 It is only possible to calculate the probability of finding an
electron within a given space
 Discovery (~1925):
 Electrons travel in clouds around
the nucleus
 Electrons can behave like waves or
particles
 The “Electron Cloud Model”
or “Quantum
Mechanical Model”:
 There are no defined orbits of
electrons around the nucleus, just
areas where they “might” orbit
ATOMIC THEORY TIMELINE- RECAP