Transcript Unit 6 - Periodic Table Unit

UNIT 6: PERIODIC TABLE
How has the Periodic Table evolved overtime?
How is the Periodic Table arranged?
What are properties and locations of metals and nonmetals?
Are there patterns (trends) within the Periodic Table?
How can we explain the patterns (trends) of the Periodic
Table?
Honors Chemistry – Ms. Argenzio
1864
John Newlands, an English
scientist listed all the known elements
by their atomic masses.
Elements with the least
amount of mass were first
followed by elements with
greater masses
1869

Dimitri Mendeleev, Russian scientist
organized elements according to their
atomic mass and properties
Developed a chart with
columns and rows
Columns called
family or group
Families contained elements with similar
properties
Each row is called period
Left to right across a
period elements increase
in atomic mass
Mendeleev believed there were more
elements that would be added and left
places in his chart empty
MODERN PERIODIC TABLE
Lists elements according to their atomic
number
Still used columns called families which
consist of elements with similar properties
Still uses rows called periods . Elements
increase by 1 moving from left to right.
Periodic table lists 118 element.
May need to be revised as new elements are
discovered.
Periodic Table
Geography
The horizontal rows of the periodic table
are called PERIODS.
The elements in any group
of the periodic table have
similar physical and chemical
properties!
The vertical columns of the periodic table
are called GROUPS, or FAMILIES.
Periodic Law
When elements are arranged in order of
increasing atomic number, there is a
periodic pattern in their physical and
chemical properties.
The periodic table is the most important
tool in the chemist’s toolbox!
http://www.brainpop.com/science/matterandche
mistry/periodictableofelements/zoom.weml
AIM: What are the properties and locations of
metals and nonmetals?
PROPERTIES:
Ductile: able to be pulled into a wire
Malleable: able to be hammered into shapes
Brittle: will shatter into pieces if struck
Luster: shiny
Dull: not shiny
AIM: What are the properties and
locations of metals and
nonmetals? - METALS
• Location: to the left of the staircase
• State(s) the metals exist as at STP: all solids
except Hg – liquid
• Properties:
– Malleable
- low ionization energy
– Ductile
- low electronegativity
– Has luster
- lose electrons to form pos
– Good conductors
ions with smaller radii
– High MP, BP
MELPS HELP!!!!!!!!!!!
AIM: What are the properties and
locations of metals and nonmetals NONMETALS
• Location: to the right of the staircase
• State(s) the metals exist as at STP: all solids
except H, He, N, O, F, Cl, Group 18Gases; Br - liquid
• Properties:
–
–
–
–
Brittle
- high ionization energy
Dull
- high electronegativity
Low MP, BP
- gain electrons to form neg
Poor conductors
ions with larger radii
AIM: What are the properties and
locations of metals and nonmetals –
TRANSITION METALS
•
Transition metals are generally located
in groups 3 to 12. They form colored ions.
When mixed with water they produce
colored _ aqueous solutions.
AIM: What are the properties and
locations of metals and nonmetals –
METALLOIDS
• Metalloids are located on the staircase
between metals and nonmetals. They
display some metallic properties and some
nonmetallic properties. There are six
metalloids
• List them below and make sure to put their
name and symbol
B, Si, Ge, As, Sb, Te
AIM: What are the properties and
locations of metals and nonmetals –
NOBLE GASES
•
Noble gases are located in group 18.
They have a full valence shell and are
therefore very stable. They are not very
reactive.
AIM: Are there patterns (trends)
within the Periodic Table? –
IONIZATION ENERGY
• Amount of energy needed to remove the
most loosely bound electron from a neutral
gaseous atom. (Listed in Table S)
PERIOD TREND
• Ex) List the ionization energies for the following
elements in period 2
Element
Ionization Energy
Li
520
B
801
F
1681
• What do you notice is happening to the ionization
energies when looking across the period from left
to right? increasing
• Values from left to right across a period increase
GROUP TREND
• Ex) List the ionization energies for the following
elements in group 2
Element
Ionization Energy
Be
900
Sr
549
Ba
503
• What do you notice is happening to the ionization
energies when looking down a group from top to
bottom? decreasing
• In a group ionization energy decrease.
AIM: Are there patterns (trends)
within the Periodic Table? –
ATOMIC RADIUS
• Atomic radius is distance the distance
between nuclei of identical atoms bonded
together. (Basically tells the size of a
neutral atom. Listed in Table S)
PERIOD TREND
• Ex) List the atomic radius for the following
elements in period 2
Element
Atomic Radius
Li
130
B
84
F
60
• What do you notice is happening to the atomic
radius when looking across the period from left to
right? decreasing
• Values from left to right across a period decrease
GROUP TREND
• Ex) List the atomic radius for the following
elements in group 2
Element
Atomic Radius
Be
99
Sr
190
Ba
206
• What do you notice is happening to the atomic
radius when looking down a group from top to
bottom? increasing
• In a group atomic radius increase.
AIM: Are there patterns (trends)
within the Periodic Table? –
ELECTRONEGATIVITY
• The electronegativity value of an atom is a
measure of its attraction for electrons when
bonded to another atom. Electronegativity
values are listed in Table S.
PERIOD TREND
• Ex) List the electronegativity values for the
following elements in period 2
Element
Electronegativity
Li
1.0
B
2.0
F
4.0
• What do you notice is happening to the
electronegativity when looking across the period
from left to right? increasing
• Values from left to right across a period increase
GROUP TREND
• Ex) List the electronegativity values for the
following elements in group 2
Element
Atomic Radius
Be
1.6
Sr
1.0
Ra
0.9
• What do you notice is happening to the
electronegativity when looking down a group
from top to bottom? decreasing
• In a group atomic radius decrease.
AIM: Are there patterns (trends)
within the Periodic Table? –
VALENCE ELECTRONS
• Valence electrons are electrons in the outer
energy level of an atom
PERIOD TREND
• Using your Periodic Table as a reference, list the
# of valence electrons for period 2 elements in the
order below)
Element
Li
Be
B
C
N
O
F
Ne
Valence e- 1
2
3
4
5
6
7
8
• What is happening to the number of valence
electrons going from left to right across a period?
Increases
Going from left to right across a period the number
of valence electrons increase.
GROUP TREND
• Using your Periodic Table as a reference, list the # of valence
electrons for group 2 elements in the order below)
Element
Atomic Radius
Be
2
Mg
2
Ca
2
Sr
2
Ba
2
Ra
2
• What is happening to the number of valence electrons as you
move down a group from top to bottom? Stay the same
• From top to bottom in a group the number of valence electrons
remains the same.
AIM: Are there patterns (trends)
within the Periodic Table? –
PRINCIPLE ENERGY LEVELS
• The orbitals in an atom form a series of
energy levels in which electrons may be
found. Each electron in an atom has its own
distinct amount of energy that corresponds
to the energy level that it occupies.
Electrons can gain or lose energy and move
to different levels.
PERIOD TREND
• Using your Periodic Table as a reference, list the # of
principle energy levels for period 2 elements in the
order below)
Element
Energy
level
Li
2
Be
2
B
2
C
2
N
2
O
2
F
2
Ne
2
• What is happening to the number of principle energy
levels going from left to right across a period? nothing
• Going from left to right across a period the number of
principle energy levels remains the same.
GROUP TREND
• Using your Periodic Table as a reference, list the # of principle
energy levels for group 2 elements in the order below)
Element
Be
Mg
Atomic Radius
2
3
Ca
Sr
Ba
4
5
6
Ra
7
• What is happening to the number of principle energy levels as you
move down a group from top to bottom? Increasing
• From top to bottom in a group the number of principle energy
levels increases.
AIM: Are there patterns (trends)
within the Periodic Table? –
METALLIC CHARACTER
• Most known elements are metals. Most
active metals are located in groups 1 and 2.
In any group on the Periodic Table the
metallic properties of the elements increase
from top to bottom.
AIM: Are there patterns (trends)
within the Periodic Table? –
IONIC RADIUS
• Atoms gain or lose electrons to become charged
particles called ions. Metals tend to lose their
valence electrons in chemical reactions to become
positive ions. Nonmetals tend to gain electrons in
chemical reactions and become negative ions.
As these atoms gain or lose electrons, they
complete an octet of valence electrons. Ionic
radius is the distance from the nucleus to the outer
principle energy level of the ion.
AIM: Are there patterns (trends)
within the Periodic Table? –
IONIC RADIUS
• When a metal loses its valence electrons and
becomes positively charged it loses an energy
level, its radius decreases. When a nonmetal
gains an electron and becomes negatively charged
its radius increases.
• **The ionic radius of metals is smaller than the
radius of the original atom. The radii of
nonmetallic ions are larger than those of the
original atoms**
Effect of atomic structure on Periodic
Trends
Magnet
Demonstration
Atomic Radius
Electronegativity
Ionization energy
Effect of atomic structure on Periodic
Trends
 Remember that all of the elements of the
periodic table are made up of the simplest
building blocks of matter called atoms
 The properties of the elements follow
general patterns called trends.
Effect of atomic structure on Periodic
Trends
 When we observe the properties across a
period or down a group, these trends can be
explained by changes in atomic structure from
one element to the next.
Effect of atomic structure on Periodic
Trends
The periodic trends of atomic radius,
electronegativity, and ionization energy can all
be explained by changes in nuclear charge,
and/ or the number of P.E.L.
Effect of atomic structure on Periodic
Trends
[Think about magnets and attraction! Nuclear
charge represents the strength of a magnet's
attractive force and the number of principle
energy levels represents the distance between
the magnets.]
ATOMIC RADIUS
ATOMIC RADIUS: Period Trend
As we look at the elements across period the
nuclear charge in each successive atom
increases. However, the number of principle
energy levels remains the same
Therefore, with each successive element the
second shell is pulled closer to the nucleus.
This causes the atomic radius to decrease
ATOMIC RADIUS: Period Trend
CONCLUSION: Increased nuclear charge (#
of protons) across the period causes the atomic
radius to decrease
ATOMIC RADIUS: Group Trend
As we go down group 1 the number of
principle energy levels increases. Therefore,
each successive atom down a group increases
in size. ( atomic radius)
ATOMIC RADIUS: Group Trend
CONCLUSION: Increased number of P.E.L.
causes the atomic radius to increase down a
group
ELECTRONEGATIVITY
The measure of the relative attraction of an
atom for a foreign electron.
ELECTRONEGATIVITY
ELECTRONEGATIVITY: Period Trend
 As we go across a period from left to right
the nuclear charge increases.
However, the number of principle energy
levels remains the same.
Therefore, elements to the right of the
periodic table have an increased attraction for
foreign electrons.( electronegativity)
ELECTRONEGATIVITY: Period Trend
CONCLUSION: Increased nuclear charge
across a period causes an increase in
electronegativity
ELECTRONEGATIVITY: Group Trend
 As we go down a group the number of P.E.L.
increases
Therefore, there is an increased shielding
effect and a weaker attraction by the nucleus
for foreign electrons
Therefore, each successive atom down a
group decreases in electronegativity
ELECTRONEGATIVITY: Group Trend
CONCLUSION: Increased number of P.E.L.
Causes an increased shielding effect, which
decreased electronegativity
IONIZATION ENERGY
The amount of energy required to remove the
outermost electron from an atom.
IONIZATION ENERGY
IONIZATION ENERGY: Period Trend
 As we go across a period from left to right
the nuclear charge increases.
However, the number of principle energy
levels remains the same.
IONIZATION ENERGY: Period Trend
Therefore, elements to the right of the
periodic table hold onto their own valence
electrons more strongly.
This means it requires a larger amount of
ionization energy exerted by a foreign atom to
remove
IONIZATION ENERGY: Period Trend
CONCLUSION: An increase in nuclear
charge across a period causes the ionization
energy to increase
IONIZATION ENERGY: Group Trend
 As we go down a group the number of P.E.L.
increases
Therefore, there is an increased shielding
effect and a weaker attraction for its own
valence electrons
Therefore, it requires less ionization energy
to remove a valence electron from these atoms
as we go down a group
IONIZATION ENERGY: GROUP Trend
CONCLUSION: An increased shielding
effect due to an increasing number of P.E.L.
causes a decrease in ionization energy down a
group