Download CHAPTER-5-PPT - Fordson High School

CHAPTER 5
THE BOHR MODEL
• Bohr proposed
that an electron is
found only in
specific circular
path, or orbits
around the
nucleus.
• Each possible
electron orbit has
a fixed energy
called an energy
Hydrogen
ELEMENTS ARE THE NEW BUILDING
BLOCKS
Hydrogen
Nitrogen-7
Carbon-6
Oxygen-8
ENERGY LEVELS
 Fixed energy levels of
electrons are similar to rungs
of a ladder.
 The lowest possible energy
level is called its ground
state.
 Just like a person an electron
can climb from one rung
(energy level) to another. It
can not be found in between
rungs (energy levels).
 To move from one level to
another an electrons must
gain or lose energy.
QUANTUM
 Amount of energy
required to move an
electron from one
energy level to
another.
 The amount of
energy an electron
gains or loses in an
atom is not always
the same.
 The higher energy
levels are closer
together so it takes
less energy to move
between levels
LIMITATIONS TO BOHR’S
MODEL
• Explained Hydrogen observed spectral light but failed
to explain the spectrum of any other element.
• Bohr’s Model did not fully account for the chemical
behavior of atoms.
• Electrons do not move around the nucleus in circular
orbits. In fact, later experiments demonstrated that
Bohr’s model was fundamentally incorrect.
QUANTUM MECHANICAL
MODEL
 No exact
electron path
 Determines
energies of an
electrons
 Electron
location is
based on how
likely it can be
found at a
particular
location.
ATOMIC ORBITALS
 Region of space in which there is a high
probability of finding an electron
 Energy levels are labeled by numbers, n= 1, 2,
3, 4, 5, 6 or 7
 Each energy level has orbitals
 Orbitals are labeled by letters and different
letters have different shapes
SUMMARY OF PRINCIPAL
ENERGY LEVELS, SUBLEVELS,
AND ORBITALS
Principal energy level
Number of
sublevels
Type of sublevel
n=1
1
1 s (1 orbital)
n=2
2
2 s (1 orbital), 2p (3 orbtials)
n=3
3
3s (1 orbital), 3p (3 orbtials), 3d
(5 orbitals)
n=4
4
4s (1 orbital), 4p (3 orbtials), 4d
(5 orbitals), 4f (7 orbitals)
S ORBITAL
P ORBITAL
D ORBITALS
F ORBITALS
• http://www.wordle.net/show/wrdl/7295272/Ground_Sta
te
• http://www.wordle.net/show/wrdl/7295304/Quantum_
Number
• http://www.wordle.net/show/wrdl/7295340/Heisenberg
_Uncertainty_Principle
• http://www.wordle.net/show/wrdl/7295360/Quantum_
Mechanical_Model_of_the_Atom
• http://www.wordle.net/show/wrdl/7295377/Atomic_Or
bital
• http://www.wordle.net/show/wrdl/7295391/Principal_Q
uantum_Number
• http://www.wordle.net/show/wrdl/7295398/Principal_En
ergy_Level
• http://www.wordle.net/show/wrdl/7295417/Energy_Sub
level
ELECTRONS PER ENERGY
LEVEL
Maximum number of electrons
n = 1 : 2 electrons
n = 2 : 8 electrons
n = 3 : 18 electrons
n = 4 : 32 electrons
ELECTRON CONFIGURATION
Arrangement of
electrons in orbitals
around the nucleus
of an atom
3 rules
1. Aufbau principle
2. Pauli exclusion
priniciple
3. Hund’s rule
AUFBAU PRINIPLE
•Electrons
enter the
lowest
energy
orbital
available.
PAULI EXCLUSION PRINICPLE
 An orbital can hold at most 2 electrons, if 2 electrons are
present they must have opposite spins
 An electron is able to spin in only one of two directions.
An up or down arrow indicates the electron’s spin ↑ or ↓,
 An orbital with paired electrons is written as
(filled orbital).
HUND’S RULE
• Negatively charged electrons repel each
other.
• Hund’s rule states that single electrons with the
same spin must occupy each equal energy
orbital before additional electrons with
opposite spins can occupy the same orbitals.
THREE RULES THAT DEFINE
ELECTRON ARRANGEMENT
• Aufbau principle:
states that each electron occupies the lowest
energy orbital available.
• Pauli exclusion principle:
states that a maximum of two electrons can
occupy a single atomic orbital.
• Hund’s rule:
states that single electrons with the same spin
must occupy each equal energy orbital before
additional electrons with opposite spin can
occupy the same orbital.
ORBITAL FILLING
Electron
Element
1s
2s
2px
2py
2pz
3s
H
Li
O
F
Ne
Na
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Configuration
EXCEPTIONAL ELECTRON
CONFIGURATION
• There are always exceptions to the
rules
• Cr : 1s2 2s2 2p6 3s2 3p6 3d5 4s1
• Cu :1s2 2s2 2p6 3s2 3p6 3d10 4s1
• Exceptions due to subtle electron
interactions in orbitals with similar
energies
LIGHT
• The study of light led to the quantum mechanical
model
• Newton: light consists of particles
Wavelength
• Huygens: light travels in waves
C=λν
frequency
Speed of light = 3.00 x 108 m/s
Wavelength and frequency of light
are inversely proportional
ELECTROMAGNETIC
SPECTRUM
What color in the
visible spectrum
has the longest
wavelength?
Red
Which color in the
visible spectrum
has the highest
energy?
Violet
the arrangement of types of
radiation from long wavelengths
to short wavelengths
CALCULATIONS
•Calculate the wavelength
of the yellow light emitted
by a sodium lamp if the
frequency of the radiation
is 5.10 x 1014 Hz (5.10 x 1014
/s) and the speed of light is
3.00 x 108 m/s.
GUIDED PRACTICE
• Step 1: Write the Given
• C = 3.00 x 108 m/s
• v = 5.10 x 1014 Hz
• Step 2: Write the Equation
• C = λV
• Step 3: Plug in your given
• 3.00 x 108 m/s = (λ) (5.10 x 1014 Hz)
STEP 4: SOLVE
 3.00 x 108 m/s = (λ) (5.10 x 1014 Hz)
5.10 x 1014 Hz
5.10 x 1014 Hz
 3.00 x 108 m/s = λ
5.10 x 1014 Hz
 λ = 5.88 x 10-7 m
TRY THIS PROBLEM
•Calculate the wavelength
of the purple light emitted
by a potassium lamp if the
wavelength of the radiation
-7
is 4.047 x 10 m and the
speed of light is 3.00 x 108
m/s.
ATOMIC SPECTRA
• When atoms absorb energy electrons move
to higher energy levels these electrons then
lose energy by emitting light when they
return to the lower energy level
• Each discrete line in an emission spectrum
correspond to 1 exact frequency of light
emitted by the atom.
Atomic emission spectrum =
fingerprint
AN EXPLANATION OF
ATOMIC SPECTRA
• The light emitted by an
electron moving from a
higher to a lower
energy level has a
frequency directly
proportional to the
energy change of the
electron.
frequency
Energy
E=hν
Planck’s constant
h •ν
h •ν
n=1
n =2
QUANTUM MECHANICS
Photoelectric effect
 Einstein used
Newton idea’s
said light could be
described as
quanta of energy
that behave as
particles
 Light quanta 
photons
Quantum mechanics

The motions of
subatomic
particles and
atoms as
waves
ATOMIC SPECTRA
CHAPTER 6
HOW DID CHEMISTS BEGIN TO
ORGANIZE THE KNOWN ELEMENTS
• Chemists used the properties of elements
to sort them into groups
• Chlorine, bromine and iodine have very
similar properties
MENDELEEV’S PERIODIC
TABLE
He arranged the
elements in his
periodic table in
order of increasing
atomic mass.
The periodic table
can be used to
predict the
properties of
undiscovered
elements
HOW IS THE MODERN PERIODIC
TABLE ORGANIZED?
• Elements are arranged in order of
increasing atomic number.
PERIODIC LAW
Elements are arranged in order of
increasing atomic number
There is repeating pattern of their
physical and chemical properties
The properties of an element within a
period change as you move from
left to right
The pattern of properties within a
period repeats as you move from
one period to the next.
WHAT ARE THREE BROAD
CLASSES OF ELEMENTS?
• Metals, Nonmetals and Metalloids
Metals
Nonmetals
Good
conductors
Poor
conductors
80% of
elements are
metals
Dull and
brittle
High luster,
ductile &
malleable
Most are
gases at
room
temperature
Metalloid
Properties of
both metals
and
nonmetals
Behavior can
be controlled
by changing
conditions
METALS
NONMETALS
METALLOIDS
IDENTIFY THE ELEMENT
Non Metal
• Carbon (C ) ______________
Metalloid
• Boron (B) ________________
Metal
• Calcium (Ca) _____________
Metal
• Barium (Ba) ______________
Metal
• Copper (Cu) ______________
Non Metal
• Bromine (Br) ______________
Non Metal
• Neon (Ne) ________________
Metalloid
• Silicon (Si) _______________
Non Metal
• Iodine (I) _________________
WHAT TYPE OF
INFORMATION CAN BE
DISPLAYED IN A PERIODIC
TABLE?
Symbols, names of elements, and information
about the structure of the atom
Horizontal rows are called
periods
Period indicates the
number of occupied
electron shells
Vertical
columns are
called
families or
groups
(elements
have similar
properties)
THE BACKGROUND COLORS IN THE SQUARES
ARE USED TO DISTINGUISH GROUPS OF
ELEMENTS
Group 1A: alkali metals
Group 2A: alkaline earth metals
Group 7A: halogens
HOW CAN ELEMENTS BE CLASSIFIED
BASED ON THEIR ELECTRON
CONFIGURATION?
Noble Gases
Elements
in group
8A
Representative
Elements
Elements
in groups
1A – 7A
Transition
Elements
Inner transition
metals
Elements
in Group
B in main
part of
periodic
table
The
elements
below
the main
body of
the
periodic
table
BLOCKS OF ELEMENTS
NOBLE GAS
Noble gases are elements in Group 8A
THE REPRESENTATIVE
ELEMENT
 Elements in groups 1A through 7A are
often referred to as representative
elements because they display a wide
range of physical and chemical
properties.
 The s and p sublevels of the highest
occupied energy level are not filled
 The group number equals the number of
electrons in the highest occupied energy
level
GROUP 1A
Group 1A: one electron in the highest
occupied energy level
GROUP 4A
Group 4A: four elements in the highest
occupied energy level
TRANSITION ELEMENTS
 There are two types of transition elements
– transitions metals and inner transition
metals.
 They are classified based on their electron
configurations
 In atoms of a transition metal, the highest
occupied s sublevel and nearby d sublevel
contain electrons
 In atoms of an inner transition metal, the
highest occupied s sublevel and a nearby
f sublevel generally contain electrons
ATOMIC SIZE
The atomic radius is one half of the
distance between the nuclei of two
atoms of the same element when
the atoms are joined.
IN GENERAL, ATOMIC SIZE INCREASES FROM TOP
TO BOTTOM WITHIN A GROUP AND DECREASES
FROM LEFT TO RIGHT ACROSS A PERIOD.
Size generally increases
Size generally decreases
IONS: DURING REACTIONS BETWEEN METALS AND
NONMETALS, METAL IONS TEND TO LOSE ELECTRONS
AND NONMETALS TEND TO GAIN ELECTRON
• Cations are positive ions,
they lose electrons
• Anions are negative ions
and they gain electrons
IONIC SIZE
Cations are smaller then the
atoms and anions are larger
then the atoms
TRENDS IN IONIC SIZE:
Size of cation decreases
Size of anion decreases
In general, ionic size of cations and anions
decrease from left to right across periods
and increase from top to bottom within
groups.
IONIZATION ENERGY
Ionization energy is the energy
required to remove an electron
fro an atom.
TRENDS IN IONIZATION ENERGY
Energy generally increases
In general the ionization energy tends to
increase from left to right across a period
and decrease from top to bottom within a
group.
ELECTRON AFFINITY
• The energy change involved when a
electron is added to a gaseous atom
+ e- →
ELECTRON AFFINITY
Increase
D
e
c
r
e
a
s
e
In general, the electron affinity increases from
left to right across a period and decrease from
top to bottom within a group.
ELECTRONEGATIVITY
• Electronegativity
is the ability of an
atom to attract
electrons to itself
when bonded to
another atom
ELECTRONEGATIVITY
E
l
e
c
t
r
o
n
e
g
a
t
v
i
t
y
d
e
c
r
e
a
s
e
s
Electronegativity increases
In general, electronegativity
decreases fro top to bottom within a
group and increase from left to right