Transcript No Slide Title

Periodic Table and Electron
Structure
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Groups of Elements
 Vertical columns on the periodic table
 Similar physical properties
 Similar chemical properties
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Groups
1
2
3
4
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6
7
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Names of Some Groups of
Elements
 Group 1
Alkali Metals
 Group 2
Alkaline Earth Metals
 Group 7
Halogens
 Group 8
Noble Gases
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Location of Some Groups
1
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3
4
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6 7
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Periods on the Periodic Table
 Horizontal rows from Group 1 to Group 8.
 Numbered 1, 2, 3, ….
 Include representative elements and
transition elements
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Periods on the Periodic Table
1
2
3
4
5
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Learning Check PE 1
A. Element in Group VIIA, period 4
1) Br
2) Cl
3) Mn
B. Element in Group IIA, Period 3
1) beryllium
2) magnesium
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3) boron
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Solution PE 1
A. Element in Group 7A, period 4
1) Br
B. Element in Group 2A, Period 3
2) magnesium
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Metals and Nonmetals
 Metals
On the left of the zig-zag line
 Nonmetals
On the right side of zig-zag line
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Metals and Nonmetals
Transition
metals
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Learning Check PE 2
Specify metal (1) or nonmetal (2) for each:
A. sulfur
____
B. chlorine
____
C. sodium
____
D. iron
____
E. carbon
____
F. silver
____
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Solution PE 2
Specify metal (1) or nonmetal (2) for each:
A. sulfur
__2__
B. chlorine
__2__
C. sodium
__1__
D. iron
__1__
E. carbon
__2__
F. silver
__1__
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Learning Check PE 3
Select the correct elements:
A. Metals in Group IVA
1) Ge, Sn, Pb
2) C, Si
3) C, Si, Ge, Sn
B. Nonmetals in Group VA
1) As, Sb, Bi
2) N, P, As
3) N, P, As, Sb
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Solution PE 3
A.
Metals in Group 4A
1)
Ge, Sn, Pb
B.
Nonmetals in Group 5A
2)
N, P, As
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More about Electrons
 Extremely small mass
 Located outside the nucleus
 Moving at extremely high speeds in a
sphere
 Have specific energy levels
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Energy of Electrons
 When atoms are heated, bright lines appear
called line spectra
 Electrons in atoms arranged in discrete
levels.
 An electron absorbs energy to “jump” to a
higher energy level.
 When an electron falls to a lower energy
level, energy is emitted.
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Loss and Gain of Energy
L
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G
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Learning Check PE 4
Answer with
1) Energy absorbed
2) Energy emitted
3) No change in energy
A. What energy change takes place when an
electron in a hydrogen atom moves from the
first (n=1) to the second shell (n=2)?
B. What energy change takes place when the
electron moves from the third shell to the
second shell?
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Solution PE 4
A.
1) Energy absorbed
B.
2) Energy emitted
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Bohr Model
• First model of the electron structure
• Gives levels where an electron is most likely
to be found
• Incorrect today, but a key in understanding
the atom
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Quantum Mechanics
Describes the arrangement and space
occupied by electrons in atoms
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Electron Levels (Shells)
 Contain electrons that are similar in
energy and distance from nucleus
 Low energy electrons are closest to the
nucleus
 Identify by numbers 1, 2, 3, 4, 5, 6…..
 The first shell (1) is lowest in energy, 2nd
level next and so on 1<2<3<4
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Number of Electrons
Maximum number of electrons in any
electron level = 2n2
n =1
n =2
n =3
2(1)2
2(2)2
2(3)2
=
=
=
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