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The Periodic Table
Introduction
Mendeleev’s Periodic Table
Dmitri Mendeleev
Mendeleev’s Table
 Grouped elements in columns by similar
properties in order of increasing atomic
mass.
 Found some inconsistencies - felt that the
properties were more important than the
mass, so switched order.
 Found some gaps.
 Must be undiscovered elements.
 Predicted their properties before they were
found.
Modern Russian Table
Chinese Periodic Table
A Spiral Periodic Table
“Mayan”
Periodic
Table
The modern table
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
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Elements are still grouped by properties.
Similar properties are in the same column.
Order is in increasing atomic number.
Added a column of elements Mendeleev
didn’t know about.
 The noble gases weren’t found because
they didn’t react with anything.
Orbital filling table
Group 1: Alkali Metals
 Most active metals, only found in compounds in
nature
 React violently with water to form hydrogen gas and
a strong base: 2 Na (s) + H2O (l)  2 NaOH (aq) +
H2 (g)
 1 valence electron
 Form +1 ion by losing that valence electron
 Form oxides like Na2O, Li2O, K2O
Group 2: Alkaline Earth
Metals
 Very active metals, only found in compounds
in nature
 React strongly with water to form hydrogen
gas and a base:
 Ca (s) + 2 H2O (l)  Ca(OH)2 (aq) + H2 (g)
 2 valence electrons
 Form +2 ion by losing those valence electrons
 Form oxides like CaO, MgO, BaO
Groups 3-11: Transition
Metals
 Many can form different possible charges of ions
 If there is more than one ion listed, give the charge
as a Roman numeral after the name
 Cu+1 = copper (I) Cu+2 = copper (II)
 Compounds and solutions containing these metals
can be colored.
Group 17: Halogens
 Most reactive nonmetals
 React violently with metal atoms to form
halide compounds: 2 Na + Cl2  2 NaCl
 Only found in compounds in nature
 Have 7 valence electrons
 Gain 1 valence electron from a metal to form
-1 ions
 Share 1 valence electron with another
nonmetal atom to form one covalent bond.
Group 18: Noble Gases
 Are completely nonreactive since they have
eight valence electrons, making a stable
octet.
 Kr and Xe can be forced, in the laboratory, to
give up some valence electrons to react with
fluorine.
 Since noble gases do not naturally bond to
any other elements, one atom of noble gas is
considered to be a molecule of noble gas.
This is called a monatomic molecule. Ne
represents an atom of Ne and a molecule of
Ne.
Properties of Metals
 Metals are good
conductors of heat and
electricity
 Metals are malleable
 Metals are ductile
 Metals have high tensile
strength
 Metals have luster
Properties of Metals
 Lose electrons easily
 Low ionization energy and
electronegativity.
 Form positive ions when combining with
other atoms by losing electrons.
 Elements with the most metallic
properties are in the lower left of the
periodic table.
Examples of Metals
Potassium, K
reacts with
water and
must be
stored in
kerosene
Copper, Cu, is a relatively soft
metal, and a very good electrical
conductor.
Zinc, Zn, is
more stable
than potassium
Mercury, Hg, is the only
metal that exists as a
liquid at room temperature
Properties of Nonmetals
Carbon, the graphite in “pencil lead” is a great
example of a nonmetallic element.
 Nonmetals are poor conductors of heat and
electricity
 Nonmetals tend to be brittle
 Many nonmetals are gases at room
temperature
Nonmetals
 Gain electrons easily.
 High ionization energies and
electronegativities.
 Form negative ions when combining with
metal atoms by gaining electrons.
 Produce covalent bonds by sharing electrons
with other nonmetals.
 Exist as gases, molecular solids, or network
solids at room temp. (Bromine exception).
Nonmetals Con’t
 Do not/are not have luster, good
conductors, ductile.
 Many are diatomic molecules (Br2, I2,
N2, Cl2, H2, O2, F2).
 Elements with nonmetallic properties
appear in the upper right of the periodic
table.
Examples of Nonmetals
Sulfur, S, was
once known as
“brimstone”
Graphite is not the only
pure form of carbon, C.
Diamond is also carbon;
the color comes from
impurities caught within
the crystal structure
Microspheres
of phosphorus,
P, a reactive
nonmetal
Metals & Nonmetals
Properties of Metalloids
KNOW
THESE!
Metalloids straddle the
border between metals
and nonmetals on the
periodic table.
 They have properties of both metals and
nonmetals.
Metalloids are more brittle than metals, less
brittle than most nonmetallic solids
 Metalloids are semiconductors of electricity
 Some metalloids possess metallic luster
Silicon, Si – A Metalloid
 Silicon has metallic luster
 Silicon is brittle like a nonmetal
 Silicon is a semiconductor of
electricity
Other metalloids include:
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Boron, B
Germanium, Ge
Arsenic, As
Antimony, Sb
Tellurium, Te
Metalloids
Determination of Atomic Radius:
Half of the distance between nucli in
covalently bonded diatomic molecule
"covalent atomic radii"
Periodic Trends in Atomic Radius
Radius decreases across a period
Increased nuclear charge, more protons; electrons
do not get further from nucleus.
Radius increases down a group
Addition of principal energy levels
Table of
Atomic
Radii
Ionic Radii
Cations
Anions
Positively charged ions
Smaller than the corresponding
atom
Negatively charged ions
Larger than the corresponding
atom
Table of Ion Sizes
Ionization Energy
 The energy required to remove the most loosely held
valence electron from an atom in the gas phase.
 High electronegativity means high ionization energy
because if an atom is more attracted to electrons, it
will take more energy to remove those electrons.
 Metals have low ionization energy. They lose
electrons easily to form (+) charged ions.
 Nonmetals have high ionization energy but high
electronegativity. They gain electrons easily to form
(-) charged ions when reacted with metals, or share
unpaired valence electrons with other nonmetal
atoms.
Another Way to Look at Ionization
Energy
Electronegativity
A measure of the ability of an atom in a chemical
compound to attract electrons
Electronegativities tend to increase across
a period
Why:
Electronegativities tend to decrease down a
group or remain the same
Why: Electrons farther from the
nucleus experience less nuclear attraction
Periodic Table of Electronegativities
Summation of Periodic Trends