A deeper understanding of Atomic Structure

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A deeper understanding of Atomic Structure
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Review

• Daltons theory of the atom started out as a
  solid sphere with no charges.
• Then Thomson figured out there were positive and
  negative charges in an atom.
• Rutherford determined that the positive charges
  (protons) were located in the center of the atom
  and the negative charges (electrons) were
  scattered around the nucleus
• Bohrs theory said that the protons are in the
  middle and the electrons travel in specific
  energy levels and orbits around the nucleus
• The modern model is basically the same except the
  nucleus contain protons and neutrons

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400 B.C.
Early Greek Philosophers determined that atoms
are the building blocks of matter.
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1898-1903
J.J. Thompson determines that an atom is made up
of negative electrons embedded in a sea of
positive charges .
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1911
Ernest Rutherford did some experiments with thin
metal foils and found that the positive charge is
located within a central nucleus
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1913
Neils Bohr worked under Rutherford but found
problems with his theory. He ultimately
determined that Electrons are in circular orbits
with increasing energy levels.
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Present Day
The modern atomic model shows that electrons
occupy regions of space whose shape is describe
by complex mathematical equations.
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Good Morning/Afternoon 3/2

• 1. Please take out 2 worksheets from yesterdays
  lesson.
• 2. Take out your Blue Chemistry Notes
• 3. Take out a pen/pencil

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Review

• An atom is made up of protons, neutrons and
  electrons.
• The protons and neutrons are found in the nucleus
• There has to be an equal number of protons and
  electrons
• Atomic mass is the number of protons and neutrons
• Atomic number is the number of protons (which is
  the same as the number of electrons)

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Review

• Dalton- solid sphere with no charges
• Thomson- solid sphere with positive and negative
  charges
• Rutherford- positive charges in center of atom,
  negative charges scattered around nucleus
• Bohr- protons in nucleus, electrons on energy
  levels/orbits
• Modern model- protons and neutrons in nucleus,
  electrons on energy levels

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The nucleus of an atom is surrounded by electron
shells. There are 7 different shells- 1 for each
period (row) on the Periodic Table of Elements.
Each shell is assigned a letter.
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Q
P
O
N
M
L
K
Nucleus
1
2
3
4
5
6
7
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There are also SUBSHELLS They are assigned a
letter too! They are 4 S, P, D F
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S- can hold 2 electrons max P-can hold 6
electrons max D-can hold 10 electrons max F-can
hold 14 electrons max
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K shell
S only Can hold 2 electrons max
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L Shell
S- 2 electrons max P- 6 electrons max TOTAL
ALLOWED- 8
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M Shell
S-2 electrons max P- 6 electrons max D- 10
electrons max TOTAL ALLOWED- 18
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N Shell
S-2 electrons max P- 6 electrons max D- 10
electrons max F- 14 electrons max TOTAL ALLOWED-
32
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O Shell
S-2 electrons max P- 6 electrons max D- 10
electrons max F- 14 electrons max TOTAL ALLOWED-
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P Shell
S-2 electrons max P- 6 electrons max D- 10
electrons max TOTAL ALLOWED- 18
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Q Shell
S-2 electrons max P- 6 electrons max TOTAL
ALLOWED- 8
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Lets start easy! Figuring out how to diagram
Periods 1, 2 3 are simple because you only have
sub shells S P
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Period (row) 1 1 shell- K
2
HELIUM
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Period (row) 2- 2 shells- K L
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FLUORINE
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Period (row) 3- 3 shells- K L M
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PHOSPHORUS
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Lets Practice! Using your diagram on your table
and your skittles, you will use Bohrs model to
diagram elements.
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BE
THE ANSWER
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N
THE ANSWER
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Na
THE ANSWER
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Good Morning/Afternoon 3/6

• 1. Please copy down the weekly plan from the
  board into your agenda
• 2. Take out your blue chemistry notes
• 3. Take out a pen/pencil
• HW 2 worksheets of atom diagrams

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Review Questions

• 1. Whose atomic model was described as a solid
  sphere with positive and negative charges
  scattered about?
• 2. Atoms contain three particles. What are they?
• 3. What kind of charge do all atoms have?
• 4. What are the rows going down the periodic
  table called?

J.J. Thomson
Protons, neutrons, electrons
Neutral charge- none at all
Groups or families
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• 5. The atomic mass of an element is the sum of
  __________ and ____________.
• 6. Whose atomic model was described as having
  protons in the nucleus and electrons traveling in
  specific energy levels or orbits around the
  nucleus?
• 7. The atomic number of an element is the same
  as the number of ______________.

Protons and neutrons
Neils Bohr
Protons
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• 8. If Mercurys atomic number is 80, how many
  electrons does it have?
• 9. If Titaniums atomic number is 22 and the
  atomic mass is 48, how many neutrons does it
  have?

80 because the atomic number is the number of
protons and in an atom the number of protons and
electrons are equal
26- Take the atomic mass and subtract the atomic
number to find the number of neutrons
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Diagramming elements review

• Energy levels (K, L, M, N, O, P, Q)
• K holds Ss (2)
• L holds Ss Ps (2 6) 8
• M holds Ss, Ps Ds (2 6 10)18
• N holds Ss, Ps, Ds Fs (2 61014)32
• O holds Ss, Ps, Ds Fs (2 61014)32
• P holds Ss, Ps Ds (2 6 10)18
• Q holds Ss Ps (2 6)8

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5
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12
37
20
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NowAs you move into Periods (rows) 4 and 5 it
gets a little harder! You have to add the D sub
shell.
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We already know that K can hold 2 L can hold up
to 8 M can hold up to 18 N can hold up to 32 O
can hold up to 32 P can hold up to 18 Q can hold
up to 8
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BUT
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You cannot simply take an atomic number that is
high (such as 75) and just start filling each
shell with the maximum electrons it holds
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Because your diagram will NOT be correct!
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75
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For elements in Periods 1-5 you must fill in this
order 1s- 2s-2p-3s-3p-4s-3d-4p-5s-4d-5p
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Period (row) 4- 4 shells- K, L, M, N
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SCANDIUM
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Period (row) 5- 4 shells- K, L, M, N
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ZIRCONIUM
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Period (row) 5 5 shells- K,L,M,N,O
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TECHNETIUM
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Lastly, when you move into Periods (rows) 6 7
it gets even harder because you are adding the F
sub shell!
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For elements in Periods 6-7 you must fill in this
order 1s- 2s-2p-3s-3p-4s-3d-4p-5s-4d-5p-6s-4f-5d-6
p-7s-5f-6d-7p
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Period (row) 6 6 shells
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DYSPROSIUM
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Good Morning/Afternoon 3/7

• 1. Please take out both worksheets that you had
  for homework.
• 2. PUT YOUR NAME ON BOTH!
• 3. Take out blue notes and a blank sheet of
  paper.
• 4. Writing utensil

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Why do we skip energy levels and fill 4ss before
3ds?

• Usually the higher an electron level, the higher
  the energy.
• But sometimes, the first orbital in a higher
  primary level (4s) actually have less energy than
  the top orbitals of the level below (3d).

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More specifics on why we bump around energy levels

• In the 7 energy levels (or rows on the periodic
  table) the level moves another step away from
  the nucleus.
• Once you get a lot of electrons around, they
  begin repelling one another like crazy and
  messing up the nice pattern.
• Higher sublevels have more angular momentum. All
  you need to know about angular momentum is that
  more AM tends to fling an electron farther out
  from the nucleus.
• When the number of electrons becomes large, a
  screening effect becomes so strong that it
  actually begins to overlap the next primary
  level. An added electron will then prefer to
  enter that next level rather then go to the
  orbital where it "should" be.

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More specifics on why we bump around energy levels

• The screening effect is when any electrons
  between you and the nucleus block you from the
  full effect of the protons in the nucleus.
• Boron- two innermost electrons feel all 5 protons
  in the nucleus pulling them in, but the highest
  electron sees 4 electrons between it and the
  protons in the nucleus so the total charge it
  feels is similar to 1 proton pulling it in.
• The less strongly its pulled in, the less energy
  it needs to escape.

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Why do we call the sublevels S,P,D F?

• First, they represent smaller sublevels of the
  primary rows (K,L,M,N,O,P,Q)
• The letters come from 19th century spectroscopy
  (appearance of various spectral lines in the
  energy level) and it just stuck so that is why we
  use it.
• S Sharp
• P Principal
• DDiffuse
• FFundamental

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Valence Electrons

• Valence electrons are the number of electrons in
  the outermost shell for each element
• The atom exists in its most stable configuration
  when its outermost shell is completely filled
• When the atom combines with other atoms it tends
  to gain or lose valence electrons in order to
  attain a stable configuration.
• If the valence shell of the atom is nearly
  complete (chlorine and other nonmetals) the atom
  will tend to accept electrons to complete it
• If the valence shell has few electrons (potassium
  and other metals) the atom will tend to lose
  these electrons, so that the next shell below the
  valence shell becomes a completed outermost
  shell.

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Al
13 protons 13 electrons 14 neutrons
3 valence electrons
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Li
3 protons 3 electrons 4 neutrons
1 valence electrons
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B
5 protons 5 electrons 6 neutrons
3 valence electrons
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Mg
12 protons 12 electrons 12 neutrons
2 valence electrons
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Ne
10 protons 10 electrons 10 neutrons
8 valence electrons
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Cl
17 protons 17 electrons 18 neutrons
7 valence electrons
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Fe
26 protons 26 electrons 30 neutrons
6 Ds in the M energy level (6th group of the
metals)
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Ag
47 protons 47 electrons 61 neutrons
9 Ds in the N shell. 9th group of metals
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Kr
36 protons 36 electrons 48 neutrons
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Sn
50 protons 50 electrons 69 neutrons
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Au
79 protons 79 electrons 118 neutrons
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Fr
87 protons 87 electrons 136 neutrons
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Chemical Bonding

• There are only 118 or so elements listed on the
  periodic table
• But, there are obviously more substances in
  nature than 118 pure elements. 
• This is because atoms can react with one another
  to form new substances called compounds. 
• When two or more atoms chemically bond together,
  the resulting compound is unique both chemically
  and physically from its parent atoms.  

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Two kinds of chemical bonding

• Ionic bonds- electrons are completely transferred
  from on atom to another.
• Instead of having a neutral charge, the atoms now
  are either negatively or positively charged.
  Opposite charged ions are attracted to each other
  by electrostatic forces
• Covalent bonds- When atoms share electrons.

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IONIC BONDING
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Sodium

• The element sodium is a silver-colored metal that
  reacts so violently with water that flames are
  produced when sodium gets wet. 

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1 valence electrons
11 protons 11 electrons 11-110 Charge (neutral)
Na
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Now we a full outer shell with 8 electrons. 11
protons 10 electrons 11-101 (positive charge)
Na
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Chlorine

• The element chlorine is a greenish-colored gas
  that is so poisonous that it was used as a weapon
  in World War I.

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7 valence electrons
17 protons 17 electrons 17-170 Charge (neutral)
Cl
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7 valence electrons
17 protons 18 electrons 17-18-1 Charge (negative)
Cl
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Sodium Chloride

• When chemically bonded together, these two
  dangerous substances form the compound sodium
  chloride, a compound so safe that we eat it every
  day - common table salt!

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Cl
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7 Valence Electrons
Cl
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So we bring in a 2nd chlorine atom which also
needs 1 more electron to make an outer shell
Cl
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SODIUM

• Na

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1 valence electron
11 protons-11 electrons 0 charge-neutral
Na
Take away 1 electron 11 protons-10 electrons 1
charge
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FLOURINE

• F

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7 valence electrons
9 protons-9 electrons 0 charge-neutral
F
Add 1 electron 11 protons-12 electrons -1 charge
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SODIUM FLOURINE NaF
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MAGNESIUM

• Mg

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12 protons-12 electrons 0 charge
2 valence electrons Since there is just a few, we
take these away to make the atom stable
Mg
Now we have 12 protons-10 electrons 2 charge
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OXYGEN

• O

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8 protons- 8 electrons 0 charge
6 valence electrons Since there are many, we must
add 2 to make it stable
O
Now we have 8 protons-10 electrons -2 charge
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O
MAGNESIUM OXIDE MgO
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CALCIUM

• Ca

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20 protons-20 electrons 0 charge
2 valence electrons Since there is just a couple,
we need to take away electrons to make the atom
stable
Cl
20 protons-18 electrons 2 charge
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OXYGEN

• O

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9 protons- 9 electrons 0 charge
6 valence electrons Since there are many, we must
add 2 to make it stable
O
Now we have 9 protons-11 electrons -2 charge
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O
CALCIUM OXIDE CaO
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MAGNESIUM

• Mg

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12 protons-12 electrons 0 charge
2 valence electrons Since there is just a few, we
take these away to make the atom stable
Mg
Now we have 12 protons-10 electrons 2 charge
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CHLORINE

• Cl

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17 protons-17 electrons 0 charge
7 valence electrons Since there are quite a few,
we just need to add 1
Cl
17 protons-18 electrons -1 charge
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-1
-1
Cl
Cl
MAGNESIUM CHLORIDE MgCl2
Mg
2
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Good Morning/Afternoon 3/20

• 1. Please take out your agenda and copy the plan
  for the week from the board.
• 2. Pen/pencil
• 3. Chemistry notes
• 4. Somebody please start passing back papers from
  grey bin!
• HW Chemistry test 1 on Wednesday!

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