Transcript Power Point slides

Chapter 6- The periodic
table
.
CH 6 Outline
1)
2)
3)
4)
5)
Model of the atom (Bohr and Current)
Bohr pictures
Mendeleev and the formation of the Periodic Table
PT Families and their characteristics
Trends
1)
2)
3)
4)
5)
6)
Atomic Radius
Electronegativity
Ionization Energy
Valence EActivity
Metallic character
4.1 Refinements of the atomic model
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Democritus  Dalton
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Thomson
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atom is like a charged “bb” (cathode ray tube experiments)
Rutherford
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atoms are like little “bb’s”
- Gold foil experiment – hollow charged “bb”
Bohr model of the atom (1913) – Neils Bohr – Danish
Physicist
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The Bohr model of the atom comes from the idea that
light is waves of energy
Bohr Model 1-20 atoms and ions
Heisenberg Uncertainty Principle
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There are limits to our ability to measure both a
particle’s velocity and its position at the same instant
F-Orbital
Crash Course Periodic Table Video
Origin of the Periodic Table
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Dimitri Mendeleev - publish first real periodic
table – 1869
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Based on chemical and physical properties
Listed elements in increasing atomic mass order
Left spaces for undiscovered elements
His basic rule: the elements in any group, of the table are
similar to their column-mates.
Dimitri Mendeleev
Eka - Aluminum
Ga (1875)
atomic mass
68
69.7
density
5.9
5.9
melting point low
29.8 ºC
oxide formula E2O3
Ga2O3
*also predicted Eka - Silicon- Germanium
Mendeleev formulated the original
Periodic Law
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Properties of elements are a periodic function of
their atomic mass.
Today’s Periodic Law
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1911 - Moseley (English) determines atomic
number is unique to each element so....new
Periodic Law
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When elements are arranged in order of increasing
atomic number, there is a periodic repetition of their
physical and chemical properties
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How different from Mendeleev?
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*** History lesson - After his brilliant
discovery, Moseley was drafted into the
infantry to fight for the crown in WW I.
He was killed. Only after the war was it
realized that scientists should probably not
be drafted into combat roles. That policy
exists to this day.
Review
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Metals, Non Metals and Metalloid location
Period vs Family
Group Names
Periodic Table Puzzle
Valence e- of periodic table
Metals
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Good conductors of heat and electricity
Shiny (high luster)
Ductile
Malleable
Solid at room temperature
Non Metals
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Mostly gases at room temperature (solids and
liquids do exist)
In general:
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Poor conductors of heat and electricity (insulators)
Brittle
Metalloid
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B, Si, As, Te, At, Ge, Sb
Sometimes behaves like metal, other times
like a non metal
Names of Families (brainiac video)
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Group 1 - Alkali Metals - These compounds are not
found alone in nature - why? explosive with water they are stored under kerosene - very reactive.
They react with nonmetals to form salts. They are
silvery, shiny (luster), have a low melting point, and
are soft (so soft, you can cut them with a knife).
They are malleable (able to flattened into a sheet)
and ductile (able to be drawn into a wire). Sodium
and Potassium are particularly important in body
chemistry.
Names of Families
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Group 2 - Alkaline Earth Metals - 2nd most
reactive elements.
Also not “lone state” elements.
Harder, denser than group 1. Common in sea
salts.
Names of Families
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Transition Metals - Groups 3-12. Harder, more
brittle, higher melting point than groups 1 and 2.
Form colored compounds.
Transition Metals continued
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They can't be divided neatly into groups; all
of them have very similar properties.
Also, they don't always use the same number
of valence electrons in chemical reactions.
Iron (Fe), for example, sometimes likes to
give away two electrons, and sometimes
three.
Transition Metals
Names of Families
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Halogens - Group 17 - most reactive of the
nonmetals. Not found free in nature. Solids,
liquids, and gases in this group. Widespread sea salts, minerals, living tissue. Many
applications - bleach, photography, plastics,
insecticides, non-stick kitchen items.
Names of Families
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Noble Gases - Group 18 - Least reactive
elements - used in air conditioners,
double pane windows, lights, balloons.
Names of Families
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Lanthanides - f block - rare earth elements
(not really rare) - shiny, silver, reactive, make
TV’s glow.
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Some have very interesting properties. For
example, gadolinium (Gd) is the only rare earth
that's ferromagnetic--that is, it sticks to magnets,
the way iron does. Lanthanum is the only
superconductor among them; at very low
temperatures, it loses all resistance to the flow of
electricity.
Names of Families
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Actinides - f block - unstable, radioactive all but 4 are artificially created.
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f block elements are called inner transition
elements - they were put into their current
position by Glenn Seaborg - the only living
person ever to have an element named after him.
With a Partner
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Point to an element on the periodic table,
partner has to identify it as one of the
following
Alkali Metals
Alkaline Earth Metals
Halogens
Nobel Gases
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Metalloids
Transition Metals
Lanthanides
Actinides
Study Skills Discussion
1)
2)
What is working?
What is not working?
Study Skills Review
Big Picture
1) Chunking
2) # of times > minutes studied
3) more connections the better
4) Recall > recognition
Small Picture
- location/surroundings
- resources used
- active studying
- study in blocks of time
7 Day Study Schedule
A) Test next Monday
B) Schedule Must include
- What content you are going to study
- How you will study?
- Resources (notes, flashcards, book, etc)
- How will you use the resource?
CH 6 Outline
1)
2)
3)
4)
5)
Model of the atom (Bohr and Current)
Bohr pictures
Mendeleev and the formation of the Periodic Table
PT Families and their characteristics
Trends
1)
2)
3)
4)
5)
6)
Atomic Radius
Electronegativity
Ionization Energy
Valence EActivity
Metallic character
Electron Configuration and Periodic
Properties
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Periodic Trends:
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For all of the following periodic trends you
should:
know the definition
be able to draw the trend on periodic table
drawings with arrows
explain why the trend happens
relate the trend to other trends
apply the trends on an “AB” sheet
1. Atomic Radius
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basic idea is “how big an atom is” - atoms are not
spheres with outer boundaries
2 trends: size- size increases going ↓ natural, logical
- add more shells
- Size decreases going → not logical!
why?
from left to right –
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more protons are added, but not more shells.
Higher charged nucleus pulls electrons closer.
Atomic Radius - Trend looks like…
Act It Out
Warm Up- Which is a larger atom?
1) K or Na
2) K or Zn
3) Fe or Mn
4) Mn or Cs
Warm Up: Act out Atomic Radius as a Class
2. Electronegativity
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Defn - the ability of an atom to attract
electrons while in a molecule (Linus Pauling)
Electronegativity is related to atomic size
Which atom attracts electrons better?
The smaller the atom, the more pull it has on
electrons while in a bond and therefore the
more electronegative
Trend on Periodic Table- Pauling Scale
Which is more electronegative?
1)
2)
3)
Na or K
Na or Al
P or As
How does electronegativity relate
to atomic radius?
Wks Pkt
Ionization Energy Intro
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Act out with e- in various shells
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Small vs large atom
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Which is the easiest to take (lowest E needed)?
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How will E change for 2nd or third electron?
3. Ionization energy
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energy required to remove the most loosely held electron
from the outer energy level of an atom. The closer the
electron to the nucleus the higher the Ionization energy.
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IE is related to atomic radius - 2 reasons why smaller
going down the table
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1. greater distance from the nucleus - less attraction
2. kernel electrons “shield” outer electrons from the nucleus
There is also a 2nd and 3rd IE - always higher than the first.
IE of elements greatly increases when the outer shell has been
emptied.
Which has a higher 2nd IE, Na or Mg? Which has a higher
3rd IE - Al or Mg?
Trend on the Periodic Table
Act It Out
Which has a higher Ionization
energy?
1) K or Na
2) K or Ga
3) N or P
4) S or Cl
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How is atomic radius related to Ionization
Energy?
Define and Draw the Periodic
Table Trend (without notes)
1) Atomic Radius
2) Electronegativity
3) Ionization Energy
Act it Out
1)
2)
3)
Atomic Radius
Electronegativity
Ionization Energy
4. Valence electrons
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- outer shell electrons involved with bonding
–tells you about an element’s chemical
behavior
+
Fill in the Lewis Dot Structures in
the notes
Valence Electrons
5. Activity (Reactivity)
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for metals - larger atoms are more active
why? - they lose electrons more easily
for nonmetals - smaller more active - why? –
they gain electrons more easily
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metal activity trend
nonmetal activity trend
Activity/Reactivity
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Most active metals + most active nonmetals =
most stable compounds
ex: RbF - very stable
LiBr - less stable
Which is more stable?
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CaS or KCl?
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BaCl2 or RaCl2?
6. Metallic character
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some metals are said to be more metallic than
others - really it is just a statement about their
activity. If they are more active, they are said
to be more metallic
Define and Draw Trend
1)
2)
3)
4)
5)
Atomic Radius
Electronegativity
Ionization Energy
Activity
Metallic character
Which is more metallic?
1)
K or Rb?
2)
Ca or Sr?
Group the Trends
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2)
3)
4)
Increase going right?
Increasing going left?
Increase going down?
Increase going up?
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Atomic Radius
Electronegativity
Ionization Energy
Valence EActivity
Metallic character
Define and Draw Trend
1)
2)
3)
4)
5)
Atomic Radius
Electronegativity
Ionization Energy
Activity
Metallic character
Act It Out
1)
2)
3)
4)
5)
Atomic Radius
Electronegativity
Ionization Energy
Activity
Metallic character