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Chapter 6
The Periodic Table
Section 1
Development of the Modern Periodic Table
Section 1: Development of the Modern Periodic Table
The periodic table evolved over time as scientists discovered
more useful ways to compare and organize the elements.
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What I Know
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What I Want to Find Out
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What I Learned
The History of the Periodic Table
http://www.youtube.com/watch?v=f
PnwBITSmgU
• In 1750, only 17 elements were known.
• As the rate of discovery increased, so did the
need to organize the elements
• In 1789 Antoine Lavoisier grouped the known
elements into metals, nonmetals, gases, and
earths.
Development of the Periodic Table
•
In the 1700s, Lavoisier compiled a list of all the known elements of the time.
Development of the Modern Periodic Table
Development of the Periodic Table
•
The 1800s brought large amounts of information and scientists needed a
way to organize knowledge about elements.
•
John Newlands proposed an arrangement where elements were ordered by
increasing atomic mass.
Development of the Modern Periodic Table
Development of the Periodic Table
•
Newlands noticed when the elements
were arranged by increasing atomic
mass, their properties repeated every
eighth element.
Development of the Modern Periodic Table
Development of the Periodic Table
•
Meyer and Mendeleev both demonstrated a connection between atomic
mass and elemental properties.
•
Moseley rearranged the table by increasing atomic number, and resulted in a
clear periodic pattern.
•
Periodic repetition of chemical and physical properties of the elements when
they are arranged by increasing atomic number is called periodic law.
Development of the Modern Periodic Table
Mendeleev’s Periodic Table
• Medeleev made flash cards of the 63 known elements.
(1863)
– On each card he put the name of the element, mass, and
properties.
– When he lined the cards up in order of increasing mass, a
pattern emerged.
– Mendeleev arranged the elements into row in order of
increasing mass so that elements with similar properties were in
the same column.
A deck of cards can be divided into
four suits—diamonds, spades,
hearts, and clubs. In one version of
solitaire, a player must produce an
arrangement in which each suit is
ordered from ace to king. This
arrangement is a model for
Mendeleev's periodic table.
• Periodic Table- Arrangement of elements in columns, based on a set of
properties that repeat from row to row.
• Mendeleev’s Prediction
– He could not make a complete table because many of the
elements had not yet been discovered. He had to leave spaces for
those elements.
• Eka-Aluminum – one space below Al. He predicted it would be a soft metal
with a low m.p. and a density of 5.9 g/cm3
– The close match between Mendeleev’s prediction and the actual
properties of new elements showed how useful the periodic table
could be.
• Gallium was discovered in 1875. It’s a soft metal, m.p. is 29.7 ˚C, and has a
density of 5.91 g/cm3
Heat from a person's hand
can melt gallium. In some
traffic signals, there are
tiny light emitting diodes
(LEDs) that contain a
compound of gallium
Mendeleev’s Periodic Table
• How is the table organized?
– Elements are arranged in order of increasing
mass.
• What do the long dashes represent?
– They represent undiscovered elements.
• Why are masses listed with some of the dashes,
but not with all of them?
– He was able to predict properties for some
unknown elements based on the properties
of neighboring elements.
Development of the Modern Periodic Table
The Modern Periodic Table
•
The modern periodic table contains boxes that contain the element's name,
symbol, atomic number, and atomic mass.
Development of the Modern Periodic Table
The Modern Periodic Table
•
Columns of elements are called groups.
•
Rows of elements are called periods.
•
Elements in groups 1,2, and 13–18 possess a wide variety of chemical and
physical properties and are called the representative elements.
•
Elements in groups 3–12 are known as the transition metals.
Development of the Modern Periodic Table
The Modern Periodic Table
•
Elements are classified as metals, nonmetals, and metalloids.
•
Metals are elements that are generally shiny when smooth and clean, solid
at room temperature, and good conductors of heat and electricity.
•
Alkali metals are all the elements in group 1 except hydrogen, and are very
reactive.
•
Alkaline earth metals are in group 2, and are also highly reactive.
Development of the Modern Periodic Table
The Modern Periodic Table
•
The transition elements are divided into transition metals and inner
transition metals.
•
The two sets of inner transition metals are called the lanthanide series and
actinide series and are located at the bottom of the periodic table.
Development of the Modern Periodic Table
The Modern Periodic Table
•
Nonmetals are elements that are generally gases or brittle, dull-looking
solids, and poor conductors of heat and electricity.
•
Group 17 is composed of highly reactive elements called halogens.
•
Group 18 gases are extremely unreactive and commonly called noble
gases.
•
Metalloids, such as silicon and germanium, have physical and chemical
properties of both metals and nonmetals.
Development of the Modern Periodic Table
Staircase
• Left side is metals: Elements to the left of the semimetal line on the periodic table are malleable (can be
hammered into a shape), ductile (can be stretched into
a wire) and good conductors of heat and electricity.
These elements tend to lose electrons to form cations.
• Right side is nonmetals: Elements to the right of the
semi-metal line on the periodic table (and hydrogen)
are brittle and insulators of heat and electricity. These
elements tend to gain electrons to form anions or
share electrons as bonds to form molecules.
• On the steps is metaloids
The Modern Periodic Table
Development of the Modern Periodic Table
"The Elements"
Essential Questions
• How was the periodic table developed?
• What are the key features of the periodic table?
Development of the Modern Periodic Table
Section 2
Classification of the Elements
The PT Song
Section 2: Classification of the Elements
Elements are organized into different blocks in the periodic table
according to their electron configurations.
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What I Know
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What I Want to Find Out
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What I Learned
Organizing the Elements by Electron Configuration
• Recall electrons in the highest principal energy level are called
valence electrons. All group 1 elements have one valence electron.
Classification of the Elements
Organizing the Elements by Electron Configuration
• Group 2 elements have
two valence electrons.
The number of valence
electrons for elements
in groups 13–18 is ten
less than their group
number. The energy
level of an element’s
valence electrons
indicates the period on
the periodic table in
which it is found.
Classification of the Elements
The s-, p-, d-, and f-Block Elements
•
The shape of the periodic table becomes clear if it is divided into blocks
representing the atom’s energy sublevel being filled with valence electrons.
Classification of the Elements
The s-, p-, d-, and f-Block Elements
•
s-block elements consist of group 1 and 2, and the element helium.
•
Group 1 elements have a partially filled s orbital with one electron.
•
Group 2 elements have a completely filled s orbital with two electrons.
Classification of the Elements
The s-, p-, d-, and f-Block Elements
•
Groups 13–18 fill the p orbitals. In group 18, both the s and p orbitals of the
period’s principal energy level are completely filled.
Classification of the Elements
The s-, p-, d-, and f-Block Elements
•
The d-block contains the transition metals and is the largest block.
•
There are exceptions, but d-block elements usually have filled outermost s
orbitals, and filled or partially filled d orbitals.
•
The five d orbitals can hold 10 electrons, so the d-block spans ten groups on
the periodic table.
Classification of the Elements
The s-, p-, d-, and f-Block Elements
•
The f-block contains the inner transition metals.
•
f-block elements have filled or partially filled outermost s orbitals and filled or
partially filled 4f and 5f orbitals.
•
The 7f orbitals hold 14 electrons, and the inner transition metals span 14
groups.
Classification of the Elements
Alkali Metals
Element
Symbol
Hyperlink
Lithium
Li
Sodium
Na
• One Valence Electron
• Found in nature only in a
compound.
• Form +1 ions because they
will easily give up 1 electron
for stability.
Potassium
K
Rubidium
Rb
Cesium
Cs
•
http://www.youtube.com/watch?v=Ft4E1eCUItI
•
http://www.youtube.com/watch?v=eCk0lYB_8c0
Francium
Fr
• Group 1A
• Most reactive metals
– Reactivity increases from the
top to the bottom.
– So reactive many are kept
under oil to prevent reacting
with water or oxygen.
Alkaline Earth Metals
• Group 2A
• Have 2 Valence Electrons
• Harder than the metals in
1A.
• Form +2 Ions because they
easily give up 2 electrons for
stability.
• Magnesium used in
photosynthesis within the
chlorophyll.
• Calcium used in teeth and
bone.
•
Element
Symbol
Hyperlink
Beryllium
Be
Magnesium
Mg
Calcium
Ca
Strontium
Sr
Barium
Ba
Radium
Ra
http://www.youtube.com/watch?v=B2ZPrg9IVEo
Boron Family
 Group 3A
 Have 3 Valence electrons
 Form +3 Ions because they
easily give up 3 electrons
for stability.
 1 metalloid (Boron)
 Six metals
 Aluminum is the most
abundant metal in the
Earth’s crust.
 People are encouraged to
recycle aluminum because
it doesn’t take that much
energy to do so.
Element
Symbol
Hyperlink
Boron
B
Aluminum
Al
Gallium
Ga
Indium
In
Thallium
Tl
Ununtrium
Uut
Carbon Family
 Group 4A
 Have 4 Valence Electrons
 Form +/- 4 Ions because it
will easily lose or gain 4
electrons for stability.
 1 Nonmetal (Carbon)
 2 Metalloids
 3 Metals
 Metallic nature increases
from top to bottom.
 With the exception of water,
most of the compounds in
your body contain carbon.
 Silicon is the second most
abundant metal in the
earth’s crust.
Element
Symbol
Hyperlink
Carbon
C
Silicon
Si
Germanium
Ge
Tin
Sn
Lead
Pb
Ununquadium Uuq
Nitrogen Family
• Group 5A
• Have 5 Valence
Electrons
• Forms -3 Ions because
it will easily gain 3
electrons for stability.
• 2 nonmetals
• 2 metalloids
• 2 Metals
• Nitrogen and
Phosphorus are used
in fertilizers.
Element
Symbol
Hyperlink
Nitrogen
N
Phosphorus
P
Arsenic
As
Antimony
Sb
Bismuth
Bi
Ununpentium
Uup
Oxygen Family
 Group 6A
 Have 6 Valence Electrons
 Forms -2 Ions because it will
easily gain 2 electrons for
stability.
 3 nonmetals
 2 metalloids
 1 metal
 Oxygen is the most abundant
element in the Earth’s Crust.
 Ozone is another from of oxygen.
At ground level it can irritate your
eyes and lungs. At higher levels
it absorbs harmful radiation from
the sun.
Element
Symbol
Hyperlink
Oxygen
O
Sulfur
S
Selenium
Se
Tellurium
Te
Polonium
Po
Ununhexium Uuh
Halogens
 Group 7A
 Have 7 Valence electrons
 Form -1 Ions because it will
easily gain 1 electron for
stability.
 Most reactive nonmetals
increase from bottom to top.
 Known as “Salt Formers”
 5 nonmetals
 1 Unknown
 Fluorine is the most reactive.
 React easily with most metals.
 http://www.youtube.com/watch?v=u2ogMUDBaf4
 http://www.youtube.com/watch?v=yP0U5rGWqdg
•
Element
Symbol
Hyperlink
Fluorine
F
Chlorine
Cl
Bromine
Br
Iodine
I
Astatine
At
Ununspetium Uus
Noble Gases
• Group 8A
• 8 Valence Electrons
• Helium is the exception
with only 2 valence
electrons.
• Extremely Un-reactive (Do
not form Ions)
• Odorless and colorless.
• Used in light bulbs.
• All are used in neon lights
except argon.
• Have the most stable
electron configuration.
•
http://www.youtube.com/watch?v=QLrofyj6a
2s
Element
Helium
Symbol
Hyperlin
k
He
Neon
Ne
Argon
Ar
Krypton
Kr
Xenon
Xe
Radon
Rn
Ununoctium
Uuo
Electron Configuration and the Periodic Table
SOLVE FOR THE UNKNOWN
Use with Example Problem 1.
•
Problem
Strontium, which is used to produce red
fireworks, has an electron configuration of
[Kr]5s2. Without using the periodic table,
determine the group, period, and block of
strontium.
Response
ANALYZE THE PROBLEM
• You are given the electron configuration
of strontium.
KNOWN
Electron configuration =
UNKNOWN
[Kr]5s2
Group = ?
Period = ?
Block = ?
For representative elements, the
number of valence electrons can
indicate the group number.
The s2 indicates the strontium’s valence
electrons fill the s sublevel. Thus,
strontium is in group 2 of the s-block.
•
The number of the highest energy
level indicates the period number.
The 5 is 5s2 indicates that strontium is
in period 5.
EVALUATE THE ANSWER
The relationships between electron
configuration and position on the
periodic table have been correctly
applied.
Classification of the Elements
Essential Questions
• Why do elements in the same group have similar properties?
• Based on their electron configurations, what are the four blocks of the
periodic table?
Classification of the Elements
Section 3
Periodic Trends
Section 3: Periodic Trends
Trends among elements in the periodic table include their sizes
and their abilities to lose or attract electrons.
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What I Know
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What I Want to Find Out
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What I Learned
Periodic Table Crash Course
http://www.youtube.com/watch?v=0
RRVV4Diomg
Atomic Radius
•
Atomic size is a periodic trend
influenced by electron configuration.
•
For metals, atomic radius is half the
distance between adjacent nuclei in
a crystal of the element.
Periodic Trends
Atomic Radius
•
For elements that occur as molecules,
the atomic radius is half the distance
between nuclei of identical atoms that
are chemically bonded together.
Periodic Trends
Atomic Radius
•
Atomic radius generally decreases from left to right, caused by increasing
positive charge in the nucleus.
•
Valence electrons are not shielded from the increasing nuclear charge
because no additional electrons come between the nucleus and the valence
electrons.
•
Atomic radius generally increases as you move down a group.
•
The outermost orbital size increases down a group, making the atom larger.
Periodic Trends
Atomic Radius
Periodic Trends
Interpret Trends in Atomic Radii
Use with Example Problem 2.
Problem
Which has the largest atomic radius:
carbon (C), fluorine (F), beryllium (Be),
or lithium (Li Explain your answer in
terms of trends in atomic radii.
Response
ANALYZE THE PROBLEM
You are given four elements. First,
determine the groups and periods the
elements occupy. Then apply the
general trends in atomic radii to
determine which has the largest atomic
radius.
SOLVE FOR THE UNKNOWN
•
Determine the periods.
From the periodic table, all the elements
are found to be in period 2.
•
Apply the trend of decreasing radii
across a period.
Ordering the elements from left-to-right
across the period yields: Li, Be, C, and F.
The first element in period 2, lithium, has
the largest radius.
EVALUATE THE ANSWER
The period trend in atomic radii has been
correctly applied. Checking radii values in
Figure 11 (slide 7) verifies the answer.
Periodic Trends
Ionic Radius
•
An ion is an atom or bonded group of atoms with a positive or negative
charge.
•
When atoms lose electrons and form positively charged ions, they always
become smaller for two reasons:
1.
The loss of a valence electron can leave an empty outer orbital, resulting in a
smaller radius.
2.
Electrostatic repulsion decreases allowing the electrons to be pulled closer to the
nucleus.
Periodic Trends
Ionic Radius
•
When atoms gain electrons, they can become larger, because the addition of
an electron increases electrostatic repulsion.
Periodic Trends
Ionic Radius
•
The ionic radii of positive ions generally decrease from left to right.
•
The ionic radii of negative ions generally decrease from left to right,
beginning with group 15 or 16.
•
Both positive and negative ions increase in size moving down a
group.
Periodic Trends
Ionic Radius
Periodic Trends
Ionization Energy
•
Ionization energy is defined as the energy required to remove an electron
from a gaseous atom.
•
The energy required to remove the first electron is called the first ionization
energy.
Periodic Trends
Ionization Energy
Periodic Trends
Ionization Energy
•
Removing the second electron requires more energy, and is called the
second ionization energy.
•
Each successive ionization requires more energy, but it is not a steady
increase.
Periodic Trends
Ionization Energy
•
First ionization energy increases from left to right across a period.
•
First ionization energy decreases down a group because atomic size
increases and less energy is required to remove an electron farther from the
nucleus.
Periodic Trends
Ionization Energy
• The ionization at which the large increase in energy occurs is
related to the number of valence electrons.
• The octet rule states that atoms tend to gain, lose or share
electrons in order to acquire a full set of eight valence
electrons.
• The octet rule is useful for predicting what types of ions an
element is likely to form.
Periodic Trends
Electronegativity
•
The electronegativity of an element indicates its relative
ability to attract electrons in a chemical bond.
•
Electronegativity decreases down a group and increases left
to right across a period.
Periodic Trends
Patterns on the Periodic Table
1.
2.
3.
4.
5.
6.
7.
8.
9.
Atomic # L to R.
Atomic mass L to R.
Energy level and orbitals in rows from T to B.
(Physical Properties) metals
metalloids
nonmetals from L to R.
Columns atomic mass from T to B.
Columns are based on chemical properties
(reactivity).
Valence Electrons from L to R.
Most reactive metals are on the left side.
Most reactive non-metals are on the right side.
Periodic Table Trends Rap
Essential Questions
• What are the period and group trends of different properties?
• How are period and group trends in atomic radii related to
electron configuration?
Periodic Trends