Chapter 6
Periodic Table
World of Chemistry
Harry potter sings the element song
Periodic Table
• a chart that organizes information about
the elements
• knowing an elements location in the table
allows you to predict properties
• scientists have placed elements with
similarities in the same groups on the
table
History:
Joseph Dobereiner – Triads (1829)
• made chart of groups of three elements
that had similar properties
• ex. Ca, Ba, Sr (found Sr mass is half way
between the other two)
Dobereiner’s Triads
Triad 1
Triad 2
First
element
Calcium 40.1
Chlorine
35.3
Sulfur
Third
element
Average
Barium
Iodine
126.9
Tellurium
88.7
81.2
Second
Element
Strontium 87.6
Bromine
137.3
Triad 3
32.1
127.6
79.9
79.9
Selenium
79.0
John Newlands – Law of Octaves (1863)
• arranged in order of atomic mass
• appeared to be a repetition of properties
every eighth element
• arranged elements into groups of 7
• Law of Octaves – same properties repeat
every 8th element
• (but it didn’t account for Noble gases and
transition metals)
Law of Octaves
1
2
3
Li Be B
Na Mg Al
K
4
C
Si
5
N
P
6
O
S
7
F
Cl
Song-elemental Funkiness
Mendeleev’s Periodic Table
1869- Dmitri Mendeleev and Lothar Meyer
both demonstrated a connection between
atomic mass and properties
-Mendeleev published his table first and
better demonstrated its usefulness
Video
-placed elements with similar properties in
vertical columns called groups or families
-horizontal rows are periods
-if no known element fits in a particular
place, he left a blank (predicted the
properties of it for someone to discover
later)
Mendeleev’s Prediction
Ekasilicon (Es)
(predicted properties)
• Atomic Mass: 72
• High Melting Point
• Density: 5.5 g/ml
• Dark gray metal
• Will obtain from K2EsF6
• Slightly dissolved by HCl
• Will form EsO2
• Density of EsO2: 4.7 g/ml
Germanium (Ge) (1886)
(actual properties)
• Atomic Mass: 72.61
• Melting Point: 945° C
• Density: 5.323 g/ml
• gray metal
• Will obtain from K2GeF6
• Not dissolved by HCl
• Will form GeO2
• Density of GeO2:4.7 g/ml
Mendeleev’s Periodic
Law
• physical and chemical properties of
elements were periodic functions of their
atomic mass
• by arranging by atomic mass he did find
he had some elements in groups with
different properties (ex. Te and I, Co and
Ni)
Modern Periodic Table
-Henri Moseley’s discovery of the atomic
number corrected Mendeleev’s problems
and led to the modern table
Modern Periodic Law
• properties of elements are periodic
functions of their Atomic numbers
• found atoms of similar electron
configurations found in similar groups
• The Development of the Periodic Table
Chinese Periodic Table
German Table
(Periodensystem der
Elemente )
Russian
Norwegian
• http://no.wikipedia.org/wiki/Periodesystem
et_i_stor_utgave
• Romanian
Parts of the Periodic Table
Groups or Families
- vertical column of elements w/ similar
properties
Elemental Funkiness
Group 1- Alkali Metals
Group 2 – Alkaline Earth Metals
Group 16- Chalcogens
Group 17 – Halogens
Group 18 – Noble or Inert gases
3-12 – Transition metals
Staircase- metalloids
Bottom rows- Rare earth metals
(Lanthanoids & Actinoids or Lathanides &
Actinides)
Periods
- horizontal rows (of elements w/ common
outer energy level)
Properties of Elements
Metals:
-left side of staircase
-hard, shiny, conduct heat or electricity
well, malleable, ductile
-have 3 or fewer electrons in outer level
(3 or less dots in dot diagram)
Nonmetals
-right side of staircase
-gases or brittle solids, dull surfaces,
used as insulators
-have 5 or more electrons in outer energy
level
Metalloids
-have properties of both metals and non
metals
-found on staircase
Reading the Periodic Table
Organizing elements by
electron configuration
• Atoms in same group have similar
chemical properties because they have
similar electron configurations and similar
# of valence electrons
• Period numbers  tell us the outer most
energy levels
• The periodic table not only has rows &
columns but sections or blocks
representing the sublevels
Outer energy
levels
1
2
3
4
5
sblock
pblock
d - block
6
7
f -block
• The energy level number in front of (s) is
always the period number
• The energy level number in front of the
(p) is the period number
• The energy level number in front of the
(d) is one less than the period number
• The energy level number in front of the (f)
is 2 less than the period number
Periodic Trends
• Properties of elements change in
predictable ways depending on their
location on the periodic table because of
their electron configuration
Atomic Radius
-half the distance between adjacent nuclei
in two atoms of the element bonded
together
Trends:
Ionic Radius
• when elements lose or gain electrons to
form ions their size increase and
decreases
• an atom that loses electrons and
becomes positively charged gets smaller
• an atom that gains electrons and
becomes negatively charged gets larger
Trends:
Positive ions decrease
Generally
decreases
Negative ions decrease
Ionization Energy
-energy required to remove an electron
from a gaseous atom
Trends:
Electronegativity
• the relative ability of the atoms to attract
electrons in a chemical bond
Electronegativity Trends:
Chemical Reactivity
• Tendency of a substance to undergo a
chemical change
• Metals- reactivity increase moving
towards bottom left (Cesium)
• Nonmetals- reactivity increase moving
towards top right (fluorine)
Quest
•
•
•
•
16 multiple choice
3 going from element to configuration
7 going from configuration to name
Short answer- id elements as
metal/non/metalloid, and the group name
• Know: History (Triads, octaves,
Mendeleev), Modern periodic law=atomic
mass, trends, families)