Transcript Chapter 5: The Periodic Table

Atoms and
The Periodic Table
Learning Targets:
1. Describe atoms
2. Use the Periodic Table
Atoms
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What are atoms?
Atoms are the basic building blocks of matter
that make up everyday objects. A desk, the
air, even you are made up of atoms!
There are 90 naturally occurring kinds of
atoms. Scientists in labs have been able to
make about 25 more.
Structure of Atoms
All atoms are
made of a
• nucleus, or
center
• surrounded by
orbits of
electrons
The nucleus
is made up of 2 kinds
of particles:
• Protons-which have
a positive charge.
The number of protons
determines what element
you have.
• Neutrons-- which
have no charge. The
number of neutrons usually
matches the number of
protons, but isotopes of an
element may have different
numbers of neutrons.
Around the nucleus of an
atom, are orbits of
electrons.
Electrons are very small,
negatively charged
particles. Their negative
charge attracts them to the
positively charged protons
in the neucleus.
With your partner,
describe these 3 particles
that make up all atoms:
Electron
Proton
Neutron
First energy level
Electron orbits
exist in several
shells or energy
levels.
Second
energy
level
Scientists often illustrate
the electron arrangement
with a drawing called a Bohr
diagram. This shows the
placement of the electrons
into their energy levels.
Atoms like to have their
outside energy level full. If
it is not, they are more likely
to react with other atoms.
Water is
formed when
2 hydrogen
atoms share
electons with
1 atom of
oxygen
Elements
react when
they give,
take or share
electrons
from other
elements.
Discuss with your partner:
1. How are electrons arranged?
2. What does a Bohr diagram show
you?
3. What is likely to happen if elements
DON’T have their outer electron level
full?
4. What happens when one atom reacts
with another atom?
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What would you expect different elements to
be like?
Which elements are most likely to react?
What will they be likely to react with?
Clues to the answers to these
questions can be found
in a tool called
THE PERIODIC TABLE.
The Periodic Table
Organization of the Elements
Search for Order
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1750 only 17 elements known
1789 Antoine Lavoisier grouped known
elements (4 groups)
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Metals
Non-metals
Gases
Earths
Next 80 yrs scientists looked for better
way to classify known elements
Mendeleev’s Periodic Table
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1869….Dmitri Mendeleev
(Russian teacher and
chemist) organized known
elements while playing
solitaire
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Made deck of cards with
elements
Listed name, mass and
properties
Paid attention to how
elements reacted in
chemical reactions
Mendeleev’s Periodic Table
Strategy for organization: What did he
look at?
chemical properties
 physical properties
 atomic mass
 density
 color
 melting point
 Valence electrons (sec 5.3)
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Mendeleev’s Proposal
Elements arranged in rows based on
increasing mass.
 Elements with similar properties are in
same column.
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Chart was a Periodic Table arrangement of elements in columns
based on a set of properties that repeat.
Mendeleev’s Prediction
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Table incomplete–
elements not yet
discovered
Left spaces in table for
undiscovered elements
Good models allow for
predictions to be made
based on model
Used properties of nearby
elements to predict
properties of unknown
elements
He called this element
eka-Aluminum.
Later it was renamed
Gallium after its
discovery in 1875
Evidence Supporting
Mendeleev’s Table
 Close match between Mendeleev’s
predictions and the actual
properties of new elements showed
how useful table was.
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Ex. Discovery of: Aluminum, Gallium, Scandium,
and Germanium
http://www.iteachbio.com/Chemistry/Chemistry/The%20Periodic%20Ta
ble.mov
YOU NEED 3 DIFFERENT
COLORED PENCILS
Section 5.2
The Modern Periodic
Table
The Elements by Tom Lehrer
The Modern Periodic Table
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“Periodic” - Repeating patterns
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Listed in order of increasing number of
protons (atomic #)
Properties of elements repeat
Periodic Law- when elements arranged by
increasing number of protons, properties
repeat in pattern
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Columns in the Periodic Table
-vertical (up & down)
-called groups or families
-#ed 1-18 or 1A through 8A
-elements in same family have
similar properties
Rows in the Periodic Table
-horizontal (left – right)
-called a period
-properties change greatly across period
-first element in period is very active
metal
-last element in most periods is noble gas
-7 periods (number them on your
periodic table)
Discuss with your partner:
Why is a chemists chart
called a PERIODIC
table—what does periodic
mean?
Element Key
Important information about an
element is given in each square
of the periodic table:
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its atomic number
chemical symbol
element name
average atomic mass
For example:
Carbon has atomic # 6
(or has 6 protons), an
average atomic mass of
12.01 and a symbol of C
6
C
Carbon
12.01
What are 4 important
pieces of information each
square of the Periodic
Table gives you about its
element?
Metals
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Most solids (Hg is liquid)
Luster – shiny.
Ductile – drawn into thin
wires.
Malleable – hammered into
sheets.
Conductors of heat and
electricity.
Include transition metals –
“bridge” between elements
on left & right of table
Non-Metals
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Properties are generally opposite of
metals
Poor conductors of heat and
electricity
Low boiling points
Many are gases at room temperature
Solid, non-metals are brittle (break
easily)
Chemical properties vary
Metalloids
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stair-step pattern
Have properties similar to
metals and non-metals
Ability to conduct heat and
electricity varies with temp
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Better than non-metals but
not metals
Section 5.3
Representative Groups
Hip Hop Classroom
The Elements
What are Valence electrons?
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outermost e-’s
Responsible for chem props
Elements in same group…
same # of VE
ALL atoms want full outer
energy level (usually 8 VE)
To get full outer energy level, some
elements:
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lose e- (metals)
gain e- (non-metals)
share electrons (some non-metals & metalloids)
1.What are valence
electrons?
2.Why are they
important?
Introducing the
ten major
groups
(families) on the
modern
Periodic Table:
Alkali Metals
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Hydrogen is not a
member of this
group.
- It is not a metal.
reactivity increases
- 1 valence electron (VE)
- soft, silver-white, shiny
metals
- never found pure
- most reactive metals
- Reactivity increases
down group
potassium
Label the Alkali Metals to your PT
Alkaline Earth Metals
- 2 VE
- not as reactive as
alkali metals
- often mixed with Al
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forms strong/light
weight alloys
magnesium
Alkaline Earth Metals
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Magnesium
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Used to make steel
(light metal w/o
losing strength)
photosynthesis
(chlorophyll)
Calcium
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bones & teeth
Chalk, limestone,
pearls, plaster
Label the Alkaline Earth Metals to
your PT
Boron Family
-3 VE
Boron
 Hard/brittle
 never found pure
in nature
 in borax...used to
make detergents
& cosmetics
Boron Family
Aluminum
 most
abundant
metal in
earth’s crust
 important
metal for
industry
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light, strong,
slow to
corrode
Aluminum
13
Al
Aluminum
26.98
Label the Boron Family on
your PT
silicon
Carbon Family
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4 VE
Can gain 4 e-, lose
4 e-, or share eMost compounds
in body contain C
Si 2nd most
abundant element
in Earth’s crust
Si used to tip saw
blades
Label the Carbon Family on
your PT
Nitrogen Family
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5 VE
Tend to gain 3 eN and P used in
fertilizers
P on tips of matches
Arsenic
Label the Nitrogen Family on
your PT
Oxygen Family
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6 VE
Tend to gain 2 eO very abundant element
S used in fertilizers
O needed for digestion
sulfur
Label the Oxygen Family on
your PT
Halogen Family (“salt-former”)
-7 VE
-most active nonmetals
-never found pure in nature
-react with alkali metals easily
(forms salts)
-F most active halogen
Halogens cont…
F
compounds in toothpaste
 Cl kills bacteria
 I keeps thyroid gland working
properly
bromine
Label the Halogen Group on your Periodic Table
The Noble Gases (Inert Gases)
- non-reactive
- outermost e- shell is
full (8 VE)
- In “neon” lights
-in earth’s
atmosphere (less
than 1%)
Neon
Label the Noble Gases on your Periodic Table
Discuss:
1.What are chemical
“families”?
2.How are they different
from periods?
Transition Metals
mercury
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Almost all solids at room temp (Hg exception)
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ductile, malleable, conductors
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VE varies
Less Reactive than Groups 1 & 2
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Fe, Co, and Ni produce magnetic field
Label the Transition Metals on your periodic table
uranium
Rare Earth Elements
Lanthanide series (period 6)
 Actinide Series (period 7)
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Some radioactive
Separated from table to make easy to
read/print
silver, silvery-white, or gray metals.
Conduct electricity
Label the Lanthanide Series on
your PT
Label the Actinide Series on
your PT
You may watch more videos about the
elements at:
http://www.periodicvideos.com/
or sing along at:
http://www.youtube.com/watch?v=zGM-wSKFBpo&feature=related
elemental funkiness - Mark Rosengarten
hip hop classroom
Did you reach our learning targets?
1. Describe atoms
2. Use the Periodic Table
Use the
table to
describe
oxygen.