LECTURE 4
Section 1-THE PERIODIC TABLE
History of Periodic Table
 John Newlands

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Placed elements in order according to their
properties and in order of increasing atomic
mass.
Discovered the Law of Octaves-Properties
appeared to repeat ever 8 elements
History of Periodic Table
 Dmitri Mendeleev
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Created the first periodic table using Newlands’
information.
Used all 63 known elements. Wrote the symbol,
physical and chemical properties, and relative
atomic mass, all on a card.
Arranged until he found a pattern.
Left gaps where elements had not been
discovered yet and predicted their properties.
History of Periodic Table
 Henry Moseley
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
40 years after Mendeleev arranged the elements,
Moseley used x-rays to look at 38 different
elements and their spectra, and realized that the
elements were arranged by atomic number, not
atomic mass.
This fixed the discrepancies that were in
Mendeleev’s table.
The Periodic Table
 Periodic Law

When the elements are arrange according
to their atomic numbers, elements with
similar properties appear at regular
intervals.
 Valence electrons

An electron that is found in the outermost
shell of an atom and that determines the
atom’s chemical properties.
The Periodic Table
 Organized by the number of protons
(it’s atomic number)
 Contains:
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Atomic number
Symbol
Name
Atomic mass
The Periodic Table
 Groups

Vertical columns (↕) containing elements
with similar properties
 Periods

Horizontal rows (↔) with predictable
trends
Section 2- A tour-Metals
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On the left of the zig-zag line
Make up most of the P.T.
Have Luster (shiny)
Good conductors of heat and electricity
Malleable (can be shaped)
Ductile (can be made into a wire)
High tensile strength (wires can hold mass)
Chapter 4
Section 2 Tour of the Periodic Table
Most Elements Are Metals, continued
The regions highlighted in blue indicate the elements that
are metals.
Chapter 4
Visual Concepts
Properties of Metals:
Malleability and Ductility
Nonmetals
 Found to the right of the zig-zag line
 INCLUDES HYDROGEN
 Many are gases at room temperature
 Solids are brittle
 Poor conductors of heat & electricity
Metalloids
Semi-Metals
 Found straddling the zig-zag line
 Some properties of metals & nonmetals
 Semiconductors of electricity
Chapter 4
Visual Concepts
Comparing Metals, Metalloids,
and Nonmetals
Group Names
 Group 1:

Alkali Metals
 Group 2:
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Alkaline Earth Metals
 Groups 3-12:
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Transition Metals
 Group 17:
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Halogens
 Group 18:
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Noble Gases
 Elements # 58 – 71
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Lanthanides
 Elements # 90 – 103

Actinides
Let’s Review
 Group 1
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Alkali Metals
Ends in s1
Soft, silvery metals
Highly reactive
Low density & melting point
Let’s Review
 Group 2
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Alkaline Earth Metals
Valence shell is s2
Denser, harder, stronger than Alkali Metals
Less reactive than alkali metals
Let’s Review
 Groups 3 – 12
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Transition metals
Elements are a little less predictable
Let’s Review
 Metalloids
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Along the staircase starting in Group 13
Valence levels  p orbital
Share properties of metals & nonmetals
Referred to as semimetals
Used as semiconductors in electronics
Let’s Review
 Group 17
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Halogens
Valence level is s2 p5
Highly reactive NONmetals
Forms salts when combined with Group 1 or
2 metals
Let’s Review
 Group 18
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Noble Gases
Valence level is s2 p6
Usually unreactive
And finally ….
 Lanthanides (f-block)
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Top Row of f-block
Shiny metals similar to Group 2
 Actinides
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Bottom Row of f-block
Naturally radioactive elements
TRENDS IN THE PERIODIC
TABLE
Section 3
What are the trends?
Atomic Radius
Down a group
•Increases
•Adding on extra
electron orbitals
•Stacking orbitals
keep getting bigger
Across a period
•Decreases
•More protons become ATTRACTED to more
electrons
Chapter 4
Section 3 Trends in the Periodic
Table
Atomic Radius, continued
 Atom’s ability to
steal an e Decreases down a
group
 Increases across a
period
Decreases
Ionization Energy
Increases
Chapter 4
Section 3 Trends in the Periodic
Table
Ionization Energy, continued
 Atom’s ability to
attract an e Decreases down a
group
 Increases across a
period
Decreases
Electronegativity
Increases
 Atom’s ability to
accept an e Decreases down a
group
 Increases across a
period
Decreases
Electron Affinity
Increases
NUCLEAR REACTIONS
Chapter 4
Visual Concepts
Nuclear Reaction
Chapter 4
Visual Concepts
Nuclear Fusion
Chapter 4
Section 4 Where Did the Elements
Come From?
Natural Elements, continued
Other Elements Form by Nuclear Reactions in Stars
ELECTRON CONFIGURATIONS
REFER BACK TO
CHAPTER 3 SECTION 3
ELECTRONS
 Found in specific regions – orbital
 4 orbitals
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s (sphere shaped)
p (dumbbell shape)
d (cross dumbbells)
f (don’t ask… it’s complicated)
s Orbitals
 Sphere shaped
 Can only hold 2 e- total
p Orbitals
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Dumbbell shape
3 positions
Each position holds 2 e6 e- total
d Orbitals
 Cross dumbbell shape
or 4 leaf clover shape
 5 positions total
 Each position holds 2 e Holds total 10 e-
f Orbitals
 Dumbbell shape surrounded by donut
shape
 7 positions
 Each position holds 2 e Holds total of 14 e-
Using the Periodic Table
Using the P.T. to Count #’s
s
Block
Using the P.T. to Count #’s
p
Block
Using the P.T. to Count #’s
d
block
Using the P.T. to Count #’s
f
Block
Chapter 4
Section 1 How Are Elements
Organized?
 Blocks of the Periodic Table
Writing Electron
Configurations
 Orbitals must fill in a particular order
 The 1st number indicates the period or
level the electron is found in.
 The letter indicates the orbital the
electron is found in.
 The exponent indicates how many
electrons are there.
Sample Problem A
Write the electron configuration for
Sodium, Na.
Sample Problem A
Write the electron configuration for
Sodium, Na.
Step 1:
Find the # of electrons (Look at the
Atomic number)
Na is Atomic # 11.
Na has 11 e-
Sample Problem A
Write the electron configuration for
Sodium, Na.
Step 2:
Follow the correct ordering and fill
orbitals
11 – 2 = 9 e- left
1s2
Sample Problem A
Write the electron configuration for
Sodium, Na.
Step 2:
Follow the correct ordering and fill
orbitals
(9 – 2 = 7 eleft)
1s2 2s2
Sample Problem A
Write the electron configuration for
Sodium, Na.
Step 2:
Follow the correct ordering and fill
orbitals
(7 – 6 = 1 eleft)
1s2 2s2 2p6
Sample Problem A
Write the electron configuration for
Sodium, Na.
Step 2:
Follow the correct ordering and fill
orbitals
(1 – 1 = 0 eleft)
DONE!
1s2 2s2 2p6 3s1
Sample Problem B
Write the electron configuration for
Argon, Ar.
Sample Problem B
Write the electron configuration for
Argon, Ar.
Step 1:
Find the # of electrons (Look at the
Atomic number)
Ar is Atomic # 18.
Ar has 18 e-
Sample Problem B
Write the electron configuration for
Argon, Ar.
Step 2:
Follow the correct ordering and fill
orbitals
18 – 2 = 16 e- left
1s2
Sample Problem B
Write the electron configuration for
Argon, Ar.
Step 2:
Follow the correct ordering and fill
orbitals
(16 – 2 = 14 eleft)
1s2 2s2
Sample Problem B
Write the electron configuration for
Argon, Ar.
Step 2:
Follow the correct ordering and fill
orbitals
(14 – 6 = 8 eleft)
1s2 2s2 2p6
Sample Problem B
Write the electron configuration for
Argon, Ar.
Step 2:
Follow the correct ordering and fill
orbitals
(8 – 2 = 6 eleft)
1s2 2s2 2p6 3s2
Sample Problem B
Write the electron configuration for
Argon, Ar.
Step 2:
Follow the correct ordering and fill
orbitals
(6 – 6 = 0 eleft)
1s2 2s2 2p6 3s2 3p6
Sample Problem C
Write the electron configuration for
Bromine, Br.
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 1:
Find the # of electrons (Look at the
Atomic number)
Br is Atomic # 35.
Br has 35 e-
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(35 – 2 = 33 eleft)
1s2
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(33 – 2 = 31 eleft)
1s2 2s2
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(31 – 6 = 25 eleft)
1s2 2s2 2p6
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(25 – 2 = 23 eleft)
1s2 2s2 2p6 3s2
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(23 – 6 = 17 eleft)
1s2 2s2 2p6 3s2 3p6
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(17 – 2 = 15 eleft)
1s2 2s2 2p6 3s2 3p6 4s2
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(15 – 10 = 5 eleft)
1s2 2s2 2p6 3s2 3p6 4s2 3d10
Sample Problem C
Write the electron configuration for
Bromine, Br.
Step 2:
Follow the correct ordering and fill
orbitals
(5 – 5 = 0 eleft)
DONE!
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
Your turn …
Writing Electron Configurations #1
Writing Noble Gas
Configurations
A Short Cut
Noble Gas Configurations
 Rules


Find the noble gas tha appears BEFORE the
element
Following the usual order, write the remaining
electrons contained in the element’s period
 Confusing…but you’ll get it.
 DON’T USE THE BACK OF YOUR TEXT!
 The ordering is incorrect and I’ll know you
cheated!! =(
Sample Problem C
Write the noble gas configuration for
Sodium.
Step 1:
Find the noble gas BEFORE sodium.
Ne appears before Na.
[Ne]
Sample Problem C
Write the noble gas configuration for
Sodium.
Step 2:
Follow the ordering, starting at the
period Na appears in.
Na is in Period 3
[Ne] 3s
Sample Problem C
Write the noble gas configuration for
Sodium.
Step 3:
Keep going until you reach Na.
Only 1 step, so ….
[Ne] 3s1
Sample Problem D
Write the noble gas configuration for
Bromine.
Step 1:
Find the noble gas BEFORE Br.
Ar appears before Br.
[Ar]
Sample Problem D
Write the noble gas configuration for
Bromine.
Step 2:
Follow the ordering, starting at the
period Br appears in.
Br is in Period 4
[Ar] 4s
Sample Problem D
Write the noble gas configuration for
Bromine.
Step 3:
Keep going until you reach Br.
[Ar] 4s2
Sample Problem D
Write the noble gas configuration for
Bromine.
Step 3:
Keep going until you reach Br.
[Ar] 4s2 3d10
Sample Problem D
Write the noble gas configuration for
Bromine.
Step 3:
Keep going until you reach Br.
[Ar] 4s2 3d10 4p5
Sample Problem E
Write the noble gas configuration for
Chromium, Cr.
Step 1:
Find the noble gas BEFORE Cr.
Ar appears before Cr.
[Ar]
Sample Problem E
Write the noble gas configuration for Cr.
Step 2:
Follow the ordering, starting at the
period Cr appears in.
Cr is in Period 4
[Ar] 4s
Sample Problem C
Write the noble gas configuration for Cr.
Step 3:
Keep going until you reach Cr.
[Ar] 4s2
Sample Problem E
Write the noble gas configuration for Cr.
Step 3:
Keep going until you reach Cr.
[Ar] 4s2 3d4
Your turn …
Writing Noble Gas Configurations
#1
Valence Electron
Configurations
The REALLY Short way.
Valence Electron
Configurations
 Rules:

Do everything you did with Noble Gas
configurations…..
EXCEPT
DON’T WRITE THE NOBLE GAS!
Writing Valence Electron
Configurations
For example: Hydrogen, H
 Look at your periodic table
 Hydrogen is:
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Period 1
s block
Only 1 electron
 Electron configurations: 1s1
Writing Valence Electron
Configurations
What is the valence configuration for
Selenium, Se.
Start at the period…
4s2 3d104p4
Your Turn …
Writing Electron Configurations &
Valence Configurations #1