Download The Periodic Table

Periodicity &
the Periodic Table
The Atom in 1869 – Dmitri Mendeleev
The First “Modern” Periodic Table
The Atom in 1869 – Dmitri Mendeleev
Mendeleev’s “Periodic” Atomic Theory
• Elements of similar atomic mass
display similar properties
• Elements with atomic masses that
increase in equal increments display
similar properties
• The elements can be arranged 2dimensionally by their properties to
predict “missing” elements.
Think you’re as smart as Mendeleev?
Periodicity
I’m a
genius!
Elements display repeating
patterns based on their
properties when arranged
into a 2-dimensional grid
Think you’re as smart as Mendeleev?
The basic idea: arrange cards so that patterns and trends follow
logical orders across and up/down your table. Find missing boxes by
finding "gaps" in the trends. Predict what's missing.
B1
C1
A2
B2
C2
B3
A1
D1
D3
D2
A3
The basic idea: arrange cards so that patterns and trends follow
logical orders across and up/down your table. Find missing boxes by
finding "gaps" in the trends. Predict what's missing.
A1 B1 C1 D1
A2 B2 C2 D2
A3 B3
D3
The basic idea: arrange cards so that patterns and trends follow
logical orders across and up/down your table. Find missing boxes by
finding "gaps" in the trends. Predict what's missing.
A1 B1 C1 D1
A2 B2 C2 D2
A3 B3
C3
D3
Alien Periodic Table
• Arrange the cards you have been given into a grid- It will
be a rectangle
• Aliens that demonstrate similar properties are adjacenteither side to side or under and over.
The Modern Periodic Table
The Modern Periodic Table
What it REALLY looks like!
GROUPS
Group
Numbers
Remember periodicity? How do
Groups relate to periodicity?
NO Group
Numbers
(Names Only)
PERIODS
Period
Numbers
And how does periodicity relate to
periods?
6.2 Classification of the Elements
• Elements can be classified into four categories based upon
their electron configurations
1.Noble gases
• He, Ne, Ar, Kr, Xe, and Rn
• Full outer s and p sublevels
2. Representative elements
• Groups 1A – 8A (this includes Noble Gases)
• Partially filled s and p sublevels
6.2 Classification of the Elements
3.
Transition metals
•
•
4.
d block
Outer s and nearby d sublevel contain electrons
Inner transition metals
•
•
f block
Outer s and nearby f sublevel contain electrons
Noble Gases
Transition Metals
Representative Elements
Inner Transition Metals
GENERAL CATEGORIES
Yeah. You gotta know ‘em.
General Properties
Usually, metals are:
• Conductive
• Shiny
• Malleable
• Ductile
• Solid at room temperature
(can you think of an exception?)
The Alkali Metals are particularly interesting:
• Very soft, cut with a knife
• Highly reactive with air and water
General Properties
Usually, non-metals are:
• Insulators
• Dull
• Brittle
• Often gaseous at room temperature
The Noble Gasses are particularly interesting:
• Exceptionally Nonreactive
The Halogens are also very interesting:
• Tend to form diatomic molecules
• Highly reactive with almost everything
General Properties
Metalloids:
• Some are like metals
• Some are like non-metals
• Properties vary greatly within a group
FAMILIES
Yeah. You gotta know ‘em.
What is similar for all elements in a group or
family?
These have 1
These have 3
They have the same number of outer level
Classification of the Elements
Electrons, particularly the
valence electrons, control many of
the chemical and physical
properties of atoms!
6.3 Periodic Trends
• Because the arrangement of elements on the
periodic table is closely linked to the electron
configuration, there are a number of trends
that can be used to predict chemical and
physical behavior.
• In order to understand and use these trends,
you must first understand how NUCLEAR
CHARGE and SHELLS AND SHIELDING
influence electron behavior.
ALL TRENDS ARE EXPLAINED BY NUCLEAR CHARGE AND
SHELLS AND SHIELDING
6.3 Periodic Trends
• Nuclear Charge
• As you move across a period or down a group, the atomic number
increases.
• This means the number of protons in the nucleus is increasing.
• With more protons, the positive pulling strength (nuclear charge) of
the nucleus is increasing
Nuclear Strength
Increases
Increases
6.3 Periodic Trends
• Shells
• Energy levels
• The higher the level, the farther from the nucleus
• Across – highest energy does not change
• Down – energy levels increase
• Shielding
• Inner level electrons interfere or shield the valence electrons
from the nucleus
• Across – shielding is constant
• Down – shielding increases
Shells and Shielding
Constant
Increases
Nuclear Charge verses Shells and
Shielding
• Period Trend
• Nuclear Strength Wins!!!
• Because Shells and Shielding are constant across
a period they don’t affect period trends
• Therefore, ALL PERIOD TRENDS are caused by
increasing nuclear charge.
Nuclear Charge verses Shells and
Shielding
• Group Trend
• Shells and Shielding Win
• Even though nuclear charge is increasing, more
Shells (your farther from the nucleus) and Shielding
(inner level electron interference) decreases the
effective nuclear strength.
• Therefore, ALL GROUP TRENDS are caused by
shells and shielding or their effect on the nuclear
charge.
Nuclear Charge verses Shells and
Shielding
S/S Increases lowering
effective Nuclear Strength
Nuclear Strength Increases
Atomic Radius
• Atomic radius – estimated as ½ the distance between
the nuclei of 2 like atoms in a diatomic molecule.
As atomic radius increases, the element
increases in size.
Atomic Size
Atomic Size
Size Decreases
Size Increases
Ion Formation
• Octet Rule – atoms will gain or lose electrons (sometimes
even sharing like in molecules) to acquire a full set of 8
valence electrons.
• Metals will lose electrons
• Nonmetals gain electrons
Two hydrogen atoms are walking down
the street.
Hey, I think I just
lost an electron!
Are you
sure!
Yeah!
I’m POSITIVE!
Ion Formation
• Cation – formed when electrons are removed from a
neutral atom
• Nucleus has a stronger pull on the remaining electrons
decreasing the size
The Cation is
smaller than the
neutral atom!
Ion Formation
• Anion – formed when electrons are added
to a neutral atom
• Nucleus has a weaker hold on the increased
number of valence electrons and the ion size
increases
The Anion is
larger than
the neutral
atom!
Ion Size
• Period Trend
• Cations and Anions both decrease in size across a period
• Group Trend
• Cations and Anions both increase in size down a group
Ionic Size
Cations decrease
Anions
decrease
Both increase
Ionization Energy
• Ionization energy – energy needed to remove an
electron from an atom
Na(g)  Na+(g) + e-
Ionization Energy
• To remove an electron you have to overcome the
nucleus’ hold on the electron.
• 1st Ionization Energy – Energy needed to remove first electron.
• 2nd Ionization Energy – Energy needed to remove a second
electron.
• This is always higher than the 1st ionization energy.
• When an electron is removed, the nucleus has a stronger hold on the
remaining electrons.
• When you have a noble gas electron configuration it becomes very
difficult to remove an electron.
Ionization Energy
Ionization Energy
•
Group Trend
•
Decreases as you go down a group
1.
2.
•
The farther the outer electrons are farther from the nucleus, the
weaker the pull.
The inner level electrons block the nucleus’ ability to attract the
valence electrons.
Period Trend
•
Increase as you go across a period
Ionization Energy
1st Ionization Energy decreases
1st Ionization Energy increases
Electronegativity
• Electronegativity – attraction of one atoms
nucleus to another atoms electrons when
they are chemically bonded
H
O
H
Water Molecule
Measure of how
strong the oxygen
nucleus attracts
the hydrogen’s
electron
Electronegativity
H
2.1
Li
1.0
Be
1.5
B
2.0
C
2.5
N
3.0
O
3.5
F
4.0
Na
0.9
Mg
1.2
Al
1.5
Si
1.8
P
2.1
S
2.5
Cl
3.0
K
0.8
Ca
1.0
Ga
1.6
Ge
1.8
As
2.0
Se
2.4
Br
2.8
Rb
0.8
Sr
1.0
In
1.7
Sn
1.8
Sb
1.9
Te
2.1
I
2.5
Cs
0.7
Ba
0.9
Tl
1.8
Pb
1.9
Bi
1.9
Electronegativity
• Period Trend
• Increases across a period
• Greater hold on electrons
• Group Trend
• Decreases down a group
• Weaker hold on the electrons
Electronegativity
Electronegativity increases
Electronegativity decreases
Designing A Periodic Table Activity
• Arrange the cards you’ve been given into a grid.
Your grid may or may not be perfectly square.
• Atoms with similar properties are adjacent, either
side to side or over and under.
• There may be “gaps” where an element should
be to make the similarity of properties make
sense. Put your blank card in the gap.
• When you’ve found the missing element,
interpolate its properties from its neighbors