Download Periodicity The Periodic Table

Dmitri Mendeleev
…arranged
elements in order
of their atomic
numbers,
such that
elements with
similar properties
fell into the same
column or group.
Periodicity
and the Periodic Table
the result…
The Periodic Table
Periods
Horizontal Rows
Groups
Metals vs. Non-Metals
Vertical Columns
Nonmetals
Metals
“Metalloids”
(Semi-conductors)
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Metals:
Non-metals
Good conductors of heat and electricity
Malleable, Ductile, Shiney
Nonconductors (insulators)
Dull, Brittle
Family: The Alkali Metals
Families of Elements
Elements grouped together by similar properties
Group 1:
Li, Na, K, Rb, Cs, Fr.
Highly Reactive
All have only 1 valence electron in s orbital
Alkali Metals
Alkaline Earth Metals
Transition Metals
Semi-Conductors
Halogens
Noble Gases
Other Non-Metals
Form
+1
cations
Family: The Alkaline Earth Metals
Family: The Transition Metals
Group 2: Be, Mg, Ca, Sr, Ba, Ra.
Groups 3 through 12
Somewhat Reactive
Generally less reactive than groups 1 and 2
All have 2 valence electrons in s orbital
d-orbital filling region of the table
Form
+2
cations
*everything
else in the
periodic
table is often
referred to
as the
Main
Group
Elements
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“Sub-Family”: The Lanthanide and
Actinide Series
Part of the transition metals
f-orbital filling region of table
Also called “Rare Earth Metals”
All
actinides
are
radioactive
Family: The “Metalloids”
(Semi-Conductors)
Intermediate conductors of heat and electricity
Silicon is used for computer chips because of its conductive
properties
Family: The Halogens
Group 17:
F, Cl, Br, I, At
Highly Reactive
All have 7 valence electrons
Form
-1
anions
Family: The Noble Gases
Group 18:
He, Ne, Ar, Kr, Xe, Rn.
Family: The Other Non-Metals
The 6 leftover elements:
Least Reactive Elements (most stable)
C, N, O, P, S, Se
O, S, Se, form –2 anions
All have full valence shell
N, P, form –3 anions
C generally does not form ions
Do not
form
ions
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Family: The Other Metals
The 8 leftover metals:
Al, Ga, In, Sn, Tl, Pb, Bi, Po
Form the same ions as the other elements in their group.
Special Case: Hydrogen
Hydrogen is in a class of its own…
it does not belong to any other family.
Often, Hydrogen occurs as a H+ ion, which is really is just a
proton!
Periodic Law
“the physical and chemical properties
of elements are periodic functions of
their atomic number”
for
example…
Electronegativity
Ionization Energy
Density
Atomic Radius
all of these properties exhibit
Periodic Trends
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Electronegativity
Electronegativity
= “electron hogging”
= the tendency of an atom
to attract electrons
“Electron Hogging”
Electronegativity
Ionization Energy
= the amount of energy needed to
remove an electron from an atom.
So it is like “cationization” energy
In general, electronegativity values increase
across a period and decrease down a group.
Ionization Energy
Sodium (Z=11) tends to lose its one
Ionization Energy
e-.
It has a low ionization energy…
…because little energy is needed
to remove the electron.
Fluorine (Z=9) tends to gain one e-.
It has a very high ionization energy…
…because a massive amount of energy
would be needed to remove an electron!
A high ionization energy…
…means the atom does not lose electrons easily
A low ionization energy…
…means the atom loses electrons easily
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Ionization Energy
Ionization Energy
1st ionization energy =
amount of energy needed to remove
the first electron from an atom.
2nd ionization energy =
amount of energy needed to remove
a second electron from an atom.
etc..
Atomic Radius
= electrons in
unbonded atoms
are constantly
moving, so it is
difficult to measure
the radius or
diameter of a
single atom…
In general, ionization energies increase across
a period and decrease down the groups.
Atomic Radius
???
so, we look
at bonded
atoms…
Atomic Radius
= one half the
distance between the
nuclei of 2 identical
atoms that are
bonded together
Usually measured in
angstroms (Å) or picometers (pm)
1 angstrom (Å) = 10–10 meters
1 picometer (pm) = 10–12 meters
Density
mass …
depends on
the number of
protons and
neutrons.
In general, atomic radii decrease across a
period and increase down a group.
= mass ÷ volume
volume …
depends on the
electron
configuration.
so,a complex pattern emerges …
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Periodic Table
You must
memorize the
following 45
element
names and
symbols.
I suggest you
make some
flash cards.
A Review;
Classification of Elements
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