2. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
1. Democritus a fifth century B.C. Greek
Models of philosopher proposed that all matter was
the Atom composed of indivisible particles called
atoms (Greek for uncuttable).
Democritus’s Model of the Atom
- No protons, electrons, or neutrons
- Solid and INDESTRUCTABLE
3. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
2. Billiard Ball Model (1803) - John
Models of Dalton viewed the atom as a small solid
the Atom sphere. Each element was composed of
the same kind of atoms. Each compound
was composed of different kinds of
atoms. Compounds are composed of
atoms in specific ratios. Chemical
reactions are rearrangements of atoms
(mass is conserved).
4. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
3. Plumb Pudding Model (1897) - Joseph
Models of John Thomson proposed that the atom
the Atom was a sphere of positive electricity (which
was diffuse) with negative particles
imbedded throughout after discovering
the electron, a discovery for which he was
awarded the Nobel Prize in physics in
1906.
5. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
4. Solar System Model - Ernest
Models of Rutherford discovered that the atom is
the Atom mostly empty space with a dense
positively charged nucleus surrounded by
negative electrons. Rutherford received
the Nobel Prize in chemistry in 1908 for
his contributions into the structure of the
atom.
6. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
5. BOHR MODEL OF THE ATOM - In
Models of 1913, Neils Bohr speculated that in the
the Atom atom, electrons revolve around the
nucleus, occupying circular orbits with
distinct energy levels.– The electrons
orbit around the nucleus like planets orbit
around the sun.
– Each orbit has a specific energy. The
orbits closest to the nucleus are the
lowest in energy, and energy increases
with distance from the nucleus.
7. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
– Each orbit has a specific energy. The
Models of orbits closest to the nucleus are the
the Atom lowest in energy, and energy increases
with distance from the nucleus.
8. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
• A hydrogen atom contains only one
Models of proton and one electron, so these energy
the Atom levels are simply numbered (e.g. 1, 2, 3,
…)
• For all other elements (w/ more than 1
proton and more than 1 electron),
principal energy levels (numbered 1, 2, 3,
…) are further divided into energy
sublevels.
• principal energy level (n): n=1,2,3,...
• energy sublevels: s, p, d, and f
9. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
Models of
the Atom
10. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
6. Electron Cloud Model (1920's)- an
Models of atom consists of a dense nucleus
the Atom composed of protons and neutrons
surrounded by electrons that exist in
different clouds at the various energy
levels. Erwin Schrodinger and Werner
Heisenburg developed probability
functions to determine the regions or
clouds in which electrons would most
likely be found. In 1927, Werner
Heisenburg stated that it is impossible to
know the exact location and velocity of a
subatomic particle at the same time.
This is know as the uncertainty principle.
11. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Probabilitie • According to Heisenburg, the precise
s and location cannot be determined, but by
Energy using equations one can determine the
Levels probability of finding an electron in a
particular spot.
• If the probable location of these
electrons is plotted, the diagram tends to
look like a cloud
12. Outcome 2-01
Outline the historical development of the Quantum Mechanical Model of the atom.
Models of the Atom
Dalton’s Model
Dalton’s model Thomson’s Plum-Pudding Rutherford’s Model
Model
Bohr’s Model Charge-cloud model
(present)
14. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy • Recall Bohr’s model involved a
Levels of number of orbits.
the • The smallest of these orbits
Quantum
Mechanical represented the lowest energy an
Model electron can have.
• It is called the ground state.
• If an electron absorbs energy it
can jump from the ground state to a
higher orbit or “higher level”.
• When an electron jumps to a
higher level it is said to be excited.
• When an excited electron falls
back a level, energy is given off.
15. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy • In the Quantum Mechanical Model
Levels of
the (cloud model), there are no distinct
Quantum orbits.
Mechanical •The spherical shell seen in
Model
diagrams is the average position
the electrons may hold for a
particular energy level.
•These new energy levels or shells
are numbered 1, 2, 3, etc. and are
called the principal quantum
number.
16. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy • The quantum mechanical model
Levels of
the states that every atom has principal
Quantum energy levels and at least one
Mechanical sublevel.
Model
• The energy within each sublevel is
slightly different.
• The number of sublevels in any
principal level is the same as the
principal quantum number.
• That means the first principal
energy level has one sublevel, the
second has two, etc.
17. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy • Each electron within a sublevel
Levels of
the has the same energy.
Quantum • The lowest sublevel in each
Mechanical principal level is called the s
Model
sublevel. (1s, 2s, 2s, etc.)
• The next higher sublevel is called
the p sublevel. There is no p
sublevel when n=1. There is a p
sublevel when n=2 or higher.
• The third sublevel is the d
sublevel and it wont be found
unless n=3 or greater.
18. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy • The fourth sublevel is the f
Levels of
the sublevel and is not found unless
Quantum n=4 or greater.
Mechanical • More sublevels exist and are
Model
called g, h, i etc. but are not
covered here.
• There exists some overlapping of
sublevels. For example, the 4s
and 3d sublevels. The 4s has a
lower energy state than does the
3d.
19. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy
Levels of
the
Quantum
Mechanical
Model
20. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Energy
Levels of
the
Quantum
Mechanical
Model
21. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
• The electrons position can be
Orbitals
identified more specifically than
the sublevels by describing the
orbital they are found in.
• A region within a sublevel or any
energy level where electrons can
be found are called orbitals.
• Each s sublevel has 1 orbital's,
each p has 3 orbital's, each d has
5 orbital's and each f has 7
orbital's.
• Each orbital can only hold two
electrons.
22. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
• With a maximum of 2 electron per
Orbitals
orbital an s sublevel can only hold
2 electrons, the p sublevel could
hold 6, the d could hold 10 and the
f could hold 14.
23. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron • Electrons exhibit a property
Spin known as electron spin. It can be
clockwise or counterclockwise.
• The Pauli Exclusion Principle
states that a maximum of two
electrons may occupy a single
atomic orbital, but only if the
electrons have opposite spins. The
atomic orbital containing two
electrons with opposite spins is
written as ↑↓.
24. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron • Orbital diagrams are used to
Spin show the placement of electrons in
orbitals.
• Arrows pointing in opposite
directions indicate electrons
spinning in opposite directions.
• Two oppositely spinning
electrons are called an orbital
pair.
25. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron • Hund’s rule states that single
Spin
& Hund’s electrons with the same spin must
Rule occupy each equal-energy orbital
before additional electrons with
opposite spins can occupy the
same orbital's.
26. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron • For example, the three 2 p
Spin
& Hund’s orbitals would be filled as
Rule
28. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron A teaching aid that students can
Spin
& Hund’s use to write the correct order for
Rule electron configurations can be to
set up a diagram as shown below:
29. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron Starting at the
Spin top of the
& Hund’s
Rule diagram, the
orbital's are
filled by
following the
direction of the
arrows in such
a manner: 1s,
2s, 2p, 3s, 3p,
4s, 3d, 4p, 5s,
4d, 5p, 6s, and
so on.
30. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron
Configurati
on
31. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron
Configurati
on
32. Outcome 2-02
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Electron
Configurati
on
33. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic • The radius of an atom is the
Radius and
Periodicity closest distance to which one
atom will approach another
atom.
• The first covalent atomic
radius refers to the effective
distance between the nucleus
of an atom and its valence
shell when the atom bonds
covalently with another atom.
34. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic • Van der Waals radius refers to
Radius and half the distance between the
Periodicity
nuclei of identical atoms at their
point of closest approach when no
bond is formed.
• A third type of radius is the
atomic radius in metals, defined
as half the distance between
nuclei of atoms arranged in a
metal-like crystalline structure.
35. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic
Radius and
Periodicity
36. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic • The atomic radii generally
Radius and decrease as you move across a
Periodicity
period. Since each additional
electron is added to the same
principal energy level, the additional
electrons are not shielded from the
increasingly positive nucleus.
• The increased nuclear charge
pulls the valence electrons closer to
the nucleus reducing the atomic
radius.
37. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic • The atomic radii generally
Radius and increase as you move down a
Periodicity
group.
• As you move down a group the
outermost orbital increases in size
shielding the valence electrons
from the pull of the nucleus.
• These factors overpower the
increased pull of the more positive
nucleus on the valence electrons
causing the atomic radius to
increase
38. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic
Radius and
Periodicity
39. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic Radius
and Periodicity
40. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Atomic
Radius
and
Periodicit
y
41. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionic When atoms lose electrons to form
Radius and positive ions (cations) they always
Periodicity
get smaller. Two factors lead to the
reduction in size. First, the lost
valence electron may lead to a
completely empty orbital. Second,
the electron shielding/repulsion are
reduced allowing the nucleus to pull
them closer to the nucleus.
42. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionic When atoms gain electrons to form
Radius and negative ions (anions) they always
Periodicity
get larger. The electron
shielding/repulsion increases
pushing the electrons farther from
the nucleus.
43. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionic a. Periodic Trends in Ionic Radii
Radius and The size of positive ions decrease
Periodicity
as you move across a period and
the size of negative ions
increase as you move across a
period.
b. Group Trends in Ionic Radii
The ionic radii of both positive and
negative ions increase as you move
down a group.
44. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionic Radius and Periodicity
45. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionization • The ionization energy of an atom
Energy and is the energy required to remove
Periodicity
the most loosely held electron from
the outer energy level of that atom
in the gas phase.
• The removal of an electron can be
represented by the equation:
M (g) + energy → M+ + e-
46. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionization • The removal of the first electron
Energy and from a neutral atom is called the
Periodicity
first ionization energy.
• The energy required to remove
the second electron is the second
ionization energy, etc.
• Each successive ionization
requires more energy because
each successive electron separates
from a particle that has increasingly
greater net positive charge.
47. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionization 1. Identify the first ionization
Energy and energies of the first 36 elements
Periodicity
(H to Kr).
2. Identify the atomic radii of the
first 36 elements.
3. Graph the atomic number versus
ionization energy for each
element & the atomic number
versus the atomic radii for each
element. Place both line graphs
on the same piece of paper.
48. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Ionization Ionization energy is the energy
Energy and required to remove an electron from
Periodicity
an atom in its gaseous state. These
values indicate how strongly an
atom’s nucleus holds onto its
valence electrons. High ionization
energy values indicate the atom has
a strong hold on the electrons. Low
ionization energy values indicate the
atom has a weak hold on the
electrons. Atoms with high ionization
values are unlikely to lose electrons
and form positive ions.
49. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic
Trends in
Ionization
Energy
50. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic • The general trend is towards an
Trends in increase in ionization energy along
Ionization
Energy with an increase in atomic number
(with some exceptions), as you
move across a period.
• The opposite holds true when you
move down a group.
51. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic • Why?
Trends in
Ionization
Energy
52. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic a. Periodic Trends in First Ionization
Trends in Energies
Ionization As you move across a period, the first
Energy ionization energy generally increases. For
example, lithium has a low first ionization
energy indicating it will easily lose an
electron to form the Li+ ion. Lithium atom
has one valence electron and it is this
electron that is easily removed from its
atom.
53. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic As you move across the row it becomes
Trends in increasingly harder to remove a valence
Ionization electron from the atom. The reason for
Energy this is that the increased nuclear charge
of each successive element produces an
increased hold on the valence electrons
thereby increasing the ionization
energies. The stronger nuclear charge
makes it harder to remove a valence
electron as the electrons are pulled closer
to the positively charged nucleus.
54. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Therefore, neon which is located at the
Trends in end of the row, has a high first ionization
Ionization energy indicating it will unlikely lose an
Energy electron to form Ne+ ion. Neon has a
stable outer energy level (8 electrons) so
it does not want to readily give up an
electron.
55. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic b. Periodic Trends in Successive
Trends in Ionization Energies
Ionization Table 6-5 (in McGraw-Hill Chemistry:
Energy Matter and Change, 192) lists the
successive ionization energies for the
period 2 elements. The table shows that
the energy required for each successive
ionization energy increases as you move
across a period. The primary reason for
this is that the increase in positive charge
binds the electrons more strongly.
.
56. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic The table also shows that for each
Trends in element, the energy required for a
Ionization specific ionization displays a significant
Energy increase. The reason for this is that atoms
tend to lose or gain electrons in order to
acquire a full energy level because this is
the most stable state. The energy jump
occurs when a core electron, as opposed
to a valence electron, is being removed.
57. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic c. Group Trends in Ionization
Trends in Energies
Ionization
Energy The ionization energies decrease as
you move down a group. The increasing
atomic size pushes the valence
electrons further away from the nucleus.
Consequently it takes less energy to
remove the electron because the
strength of attraction is less.
58. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic
Trends in
Ionization
Energy
59. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Electronegativity is defined as the ability
Trends in of an atom in a molecule to attract
Electro- electrons to itself. The first and most
negativity widely used electronegativity scale was
developed by Linus Pauling, who based
his scale on thermochemical data.
60. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Trends in electronegativity across a
Trends in period
Electro- As you go across a period the
negativity electronegativity increases. The chart
shows electronegativities from sodium to
chlorine - you have to ignore argon. It
doesn't have an electronegativity,
because it doesn't form bonds.
61. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Why does electronegativity increase
Trends in across a period?
Electro- Consider sodium at the beginning of
negativity period 3 and chlorine at the end
(ignoring the noble gas, argon). Think of
sodium chloride as if it were covalently
bonded.
62. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Why does electronegativity increase
Trends in across a period?
Electro- Both sodium and chlorine have their
negativity bonding electrons in the 3-level. The
electron pair is screened from both nuclei
by the 1s, 2s and 2p electrons, but the
chlorine nucleus has 6 more protons in it.
It is no wonder the electron pair gets
dragged so far towards the chlorine that
ions are formed.
Electronegativity increases across a
period because the number of charges on
the nucleus increases. That attracts the
bonding pair of electrons more strongly.
63. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Trends in electronegativity down a
Trends in group
Electro- As you go down a group,
negativity electronegativity decreases. (If it
increases up to fluorine, it must
decrease as you go down.) The chart
shows the patterns of electronegativity
in Groups 1 and 7.
64. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Why does electronegativity fall as
Trends in you go down a group?
Electro- Think of hydrogen fluoride and
negativity hydrogen chloride.
The bonding pair is shielded from the
fluorine's nucleus only by the 1s2
electrons. In the chlorine case it is
shielded by all the 1s22s22p6 electrons.
65. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Why does electronegativity fall as
Trends in you go down a group?
Electro- In each case there is a net pull from the
negativity centre of the fluorine or chlorine of +7.
But fluorine has the bonding pair in the
2-level rather than the 3-level as it is in
chlorine. If it is closer to the nucleus, the
attraction is greater.
As you go down a group,
electronegativity decreases because the
bonding pair of electrons is increasingly
distant from the attraction of the
nucleus.
66. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic Most chemistry texts will have a periodic
Trends in table that contains electronegativity
Electro- values for each element. By taking the
negativity difference between the values for each
element, it is possible to predict the type
of bonding that occurs between the
atoms.
67. Outcome 2-04
Identify periodic trends among the properties of elements and relate to electron configuration.
Include: atomic radii, ionic radii, ionization energy, electronegativity
Periodic
Trends in
Electro-
negativity
