Transcript Periodic Table History & Organization

Periodic Trends: All Arrows point to increases
Electronegativity, Ionization Energy, Electron Affinity
Atomic Radius, Ionic Radius, Metallic Character
Melting & Boiling Point
Reactivity
Periodic Table
Follow along in
your text
Chapter 4
Sections 1 & 2
Pages 116 - 131
I
II
III
Newlands
John Newlands (1865, English)
Organized elements
by increasing atomic mass.
Elements with similar properties were
grouped together.
Created Law of Octaves.
Every 8 elements, there is a similarity.
Mendeleev
Dmitri Mendeleev (1869, Russian)
Used Newlands’ Law of Octaves to
create the first Periodic Table.
There were some
discrepancies.
Mendeleev
Predicted properties of undiscovered
elements.
Moseley
Henry Mosely (1913, British)
Organized elements by increasing
atomic number.
Resolved discrepancies in Mendeleev’s
arrangement.
Periodic Blocks
Main Group Elements (s &p)
Transition Metals (d)
Inner Transition Metals (f)
Blocks of the Periodic Table
Periodic Law
When elements are arranged in order of
increasing atomic #, elements with similar
properties appear at regular intervals.
Atomic Radius (pm)
250
200
150
100
50
0
0
5
10
Atomic Number
15
20
Let’s Get Organized!
Vertical columns are called
“groups” or families
Same group = same number of
valence electrons
Let’s Get Organized!(cont.)
Horizontal rows are called
“periods”
Elements in each row have the
same amount of principal energy
levels occupied
Main-Group Elements
Are in s & p blocks
Silicon & oxygen account for
4 of every 5 atoms found on or
near Earth’s surface
4 groups have special names
Group 1: Alkali Metals
React with water to make alkaline
solutions (reactive)
Never in nature as lone elements
but are in compounds
1 valence electron
Li, Na, K, Ru, Cs, Fr
Group 2: Alkaline-Earth Metals
Hardly in nature as lone
elements but are usually in
compounds (highly reactive
but not as much as Group 1)
2 valence electrons
Be, Mg, Ca, Sr, Ba, Ra
Groups 3 - 12: Transition Metals
Called d-block elements because in
the center of the table
Do not always have the same outer
configurations but their outer s & d
orbitals will have the total amount of
electrons as their group number
Can 1, 2, or 3 valence e- depending
on the element with which it reacts
Group 17: Halogens
Most reactive nonmetals
7 valence electrons
F, Cl, Br, I, At
Group 18: Noble Gases
Once call inert gases because
once thought to be nonreactive
Full set of electrons in outermost
energy level
Except He, all have config of
ns2np6
He, Ne, Ar, Kr, Xe, Rn
Lanthanides & Actinides
(La # 57 - 70 & Ac #89 -102)
Called the f-block elements
Lanthanides are similar in
reactivity to alkaline-earth metals
Actinides are all radioactive due
to their unique nuclear structure
Lonely Hydrogen
Most common element in
universe (3 of 4 atoms)
Only 1 electron so reacts with
just about anything
Metals
Most elements are metal
Excellent conductors of electricity &
heat
Some are brittle; others are ductile
(can be made into wire) & malleable
(can be hammered into sheets)
Can be mixed with other elements to
form alloys (mixtures that improve
disadvantages of metals)
Metallic Characteristics
Metals
Nonmetals
Metalloids
Chemical Reactivity
Families
Similar valence e- within a group result
in similar chemical properties
1
2
3
4
5
6
7
Chemical Reactivity
1
2
3
4
5
6
7
Alkali Metals
Alkaline Earth Metals
Transition Metals
Halogens
Noble Gases
Periodic Properties
Atomic Radius
size of atom
Measured by half of
bond distance
First Ionization Energy
© 1998 LOGAL
Energy required to remove one efrom a neutral atom.
Melting/Boiling Point
© 1998 LOGAL
Atomic Radius
Atomic Radius
Increases to the LEFT and DOWN
1
2
3
4
5
6
7
Atomic Radius
Atomic Radius (pm)
250
K
200
Na
150
Li
100
Ar
50
Ne
0
0
5
10
Atomic Number
15
20
Atomic Radius
Why radius larger going down?
Higher energy levels have larger
orbitals
Shielding - core e- block the attraction
between the nucleus and the valence eWhy smaller to the right?
Increased nuclear charge without
additional shielding pulls e- in tighter
Ionization Energy
First Ionization Energy
Increases UP and to the RIGHT
1
2
3
4
5
6
7
Ionization Energy
First Ionization Energy
He
1st Ionization Energy (kJ)
2500
Ne
2000
Ar
1500
1000
500
Li
Na
K
0
0
5
10
Atomic Number
15
20
Ionization Energy
Why opposite of atomic radius?
In small atoms, e- are close to the
nucleus where the attraction is
stronger
Why small jumps within each group?
Stable e- configurations don’t want to
lose e-
Melting/Boiling Point
Melting/Boiling Point
Highest in the middle of a period.
1
2
3
4
5
6
7
Ionic Radius
Ionic Radius
Cations (+)
lose esmaller
Anions (–)
gain elarger
© 2002 Prentice-Hall, Inc.
Ionic Radius
Increases DOWN and to the LEFT
for each type of ion
1
2
3
4
5
6
7
Examples
Which atom has the larger radius?
Be or Ba
Ba
Ca or Br
Ca
Examples
Which atom has the higher 1st Ionization
Energy?
N or Bi
N
Ba or Ne
Ne
Examples
Which atom has the higher melting/boiling
point?
Li or C
C
Cr or Kr
Cr
Examples
Which particle has the larger radius?
S or
2S
2S
Al or
3+
Al
Al
Electronegativity
Numerical value of how much an
atom in a molecule attracts
electrons
Scale created by Linus Pauling
Flourine is 4.0 & other elements
are calculated relative to this value
Electronegativity
Increases UP and to the RIGHT
Same as Ionization Energy
1
2
3
4
5
6
7
Electron Affinity
The energy change that occurs
when a neutral atom gains an
electron
This is also due to increasing
nuclear charge
Literally means “love of
electrons”
Electron Affinity
Increases UP and to the RIGHT
Same as Ionization Energy &
Electronegativity
1
2
3
4
5
6
7
Examples
Which atom is most electronegative?
N or Bi
N
Ba or Rb
Ba
Examples
Which atom has the highest
electron affinity?
Be or Ba
Be
Ca or Br
Br
Examples
Which atom is more metallic?
S or Fr
Fr
Al or Ge
Ge
Summary of Trends
Ionization Energy, Electronegativity,
Electron Affinity all Increase UP &
RIGHT
Atomic Radius & Ionic Radius all
Increase DOWN & LEFT
Boiling/Melting point Increases then
Decreases across blocks
Metals are to the left of the “stairs” &
non-metals are to the right