Download The Periodic Table - Ms. Dormer

Chapter 4
THE PERIODIC TABLE
HOW ARE ELEMENTS ORGANIZED?

Groups of elements share certain properties
PERIODIC PATTERN

Newlands (1865) – Arranged elements
according to increasing atomic mass
 Properties
repeated every 8 elements
 Law of octaves

Dobereiner (early 1800s)
 Groups
 Triads
of 3 elements have similar properties
MENDELEEV
First periodic table
 63 known elements at the
time
 Mendeleev’s table contains
gaps that unknown
elements should fill
 He predicted the properties
of these unknown elements
& gave them names

MOSELEY
Arranged elements according to atomic number
 Erased the discrepancies in Mendeleev’s table

OTHER CONTRIBUTIONS
Seaborg – pulled out inner transition elements
to condense periodic table
 Ramsey – discovered noble gases

PERIODIC LAW

Elements with similar properties appear at
regular intervals (when arranged by atomic #)

Valence electrons – outermost electrons in an
atom of an element
 Electrons
that participate in chemical reactions
with other atoms
GROUPS/FAMILIES & PERIODS

Group/family = vertical column on the periodic
table
 Elements
have similar chemical properties because
of same # of valence electrons

Period = horizontal row
 Elements
have same number of occupied energy
levels (i.e. energy level 2)
GROUPS AND PERIODS
THE PERIODIC TABLE



Main Group elements
Transition elements
Inner transition elements
METALS, NONMETALS, METALLOIDS

Metals – occupy the majority of the periodic
table
 Located
to the left of the “staircase”
 Lustrous, Malleable, Ductile, Conductors
 Alloy = a solid or liquid mixture of 2 or more metals
Nonmetals – generally opposite properties of
metals
 Metalloids – have properties of both, located
along the “staircase”

METALS, NONMETALS, METALLOIDS
TRANSITION METALS
d-block elements
 Groups 3-12
 Do NOT have identical outer electron
configurations
 May lose different #’s of valence electrons
 Good conductors, ductile, malleable

LANTHANIDE & ACTINIDE SERIES
f-block elements
 Lanthanides – first row of inner transition
elements

 Shiny
metals, similar in reactivity to alkaline earth
metals

Actinides – second row
 Radioactive
4f
5f
ns2np6
ns2np5
ns2np4
ns2np3
ns2np2
ns2np1
d10
d5
d1
ns2
ns1
Ground State Electron Configurations of the Elements
ALKALI METALS – GROUP 1A (GROUP 1)




React with water to make alkaline solutions
One valence electron = VERY reactive
Lose their 1 valence electron to achieve noble gas
configuration (octet)
Soft texture, dull or shiny, good conductors
Group 1A Elements (ns1, n  2)
ALKALINE EARTH METALS – GROUP 2A (GROUP
2)
Highly reactive
 2 valence electrons
 Harder and have higher melting points than
alkali metals

Group 2A Elements (ns2, n  2)
COMMON GROUP ELEMENTS – 3A TO 5A
(GROUPS 13-15)
3, 4, or 5 valence electrons (depending on group)
 Some metals, some metalloids, some nonmetals

Group 3A Elements (ns2np1, n  2)
Group 4A Elements (ns2np2, n  2)
Group 5A Elements (ns2np3, n  2)
CHALCOGENS – GROUP 6A (GROUP 16)
Oxygen group
 6 valence electrons
 Name means “ore former”
 Nonmetals, metalloids, metals

Group 6A Elements (ns2np4, n  2)
HALOGENS – GROUP 7A (GROUP 17)
Highly reactive nonmetals
 7 valence electrons (1 short of a noble gas
configuration)
 Often react with alkali metals
 “Salt maker”

Group 7A Elements (ns2np5, n  2)
NOBLE GASES – GROUP 8A (GROUP 18)
Inert = unreactive
 8 valence electrons (full set); except He (2 e-)

HYDROGEN
Most common element in
the universe
 1 electron
 Extremely flammable
 Reacts unlike any other
element

PERIODIC TRENDS
Predictable change in a particular direction
 Reactivity of Alkali metals

 Increases

as you down the group
Reactivity of Halogens
 Increases
as you go up the group
IONIZATION ENERGY

Energy supplied to remove an electron
IE + X (g)
X+(g) + e-
Electron Shielding – outermost electrons
are not held as tightly to the nucleus due
to the inner electrons “shielding” them
Filled n=1 shell
Filled n=2
shell
Filled n=3
shell
Filled n=4 shell
Filled n=5
shell
General Trend in Ionization Energies
Increasing First Ionization Energy
Increasing First Ionization Energy
ATOMIC RADIUS
Atomic radius = ½ the distance from the center to the center of
2 like atoms that are bonded
Atomic Radii
ELECTRONEGATIVITY
Ability of an atom in a compound to attract
electrons
 Fluorine has highest electronegativity value

ELECTRON AFFINITY

Electron affinity = energy change when a
neutral atom gains an electron
ION SIZE
Cation is always smaller than atom from which it
is formed.
Anion is always larger than atom from which it is
formed.
Comparison of Atomic Radii with Ionic Radii