Transcript THE PERIODIC TABLE and PERIODIC LAW

THE PERIODIC TABLE and
PERIODIC LAW
Essential Questions
* How can we organize all the different elements?
* How can the periodic table help us organize
our chemistry knowledge?
* What can we predict about elements based
on their classification &location on the
periodic table?
II. WHY IS THE PERIODIC
TABLE IMPORTANT?
III. WHAT DOES THE
WORD “PERIODIC”
MEAN?
A. DEFINITION-Happening or repeating at regular intervals
Cyclic - happening in a cycle
B. EXAMPLES OF OTHER EVENTS
THAT ARE PERIODIC- Phases of moon
 Tides
 Seasons
IV. HISTORICAL
DEVELOPMENT OF THE
PERIODIC TABLE
A.
How was the Periodic Table
developed?
• Done by many scientists
• Tried to arrange elements in groups of three
• Based on Dalton's atomic theory
• Not very successful
• Found that when arranged by mass, the
eighth element was similar in physical and
chemical properties
• Related it to a musical scale
• Called Newland's octaves
DMITRI MENDELEEV
Why is he considered the
“Father of the Periodic Table”?
LOTHAR MEYER
Worked at the same time as Mendeleev.
Both men demonstrated a connection between
atomic mass and properties of elements.
However, Mendeleev given more credit.
WHY???
He Published First!
Why the blanks?
Giant Wall Periodic Table erected
in St. Petersburg, Russia in 1934
2. ORGANIZATION OF MENDELEEV’S TABLE
3.
LEFT BLANKS
Mendeleev left spaces on the table where
he thought undiscovered elements should go.
4. ORIGINAL PERIODIC LAW-The physical and chemical properties of elements
are periodic functions of their atomic mass.
5. MODIFICATION OF PERIODIC LAW
Locate several elements on the current table
that are not arranged according to increasing
atomic mass.
Examples:
Co 58.93 & Ni 58.69
Te 127.60 & I 126.90
Th 232.04 & Pa 231.04
U 238.03 & Np 237.05
Mendeleev’s table not completely correct.
C. HENRY MOSELEY
1887-1915
1. In 1913, Henry Mosely discovered that atoms
of each element had a unique atomic number.
2. Arranged elements by
atomic number, not atomic mass.
3. Eliminated problems from Mendeleev's table
D. MODERN PERIODIC
LAW--
STATES THAT WHEN THE ELEMENTS ARE
ARRANGED BY INCREASING ATOMIC
NUMBER, THERE IS A PERIODIC
REPETITION OF THEIR CHEMICAL
AND PHYSICAL PROPERTIES
V. ELEMENTAL
INFORMATION ON THE
PERIODIC TABLE
A. READING SQUARES OF THE
PERIODIC TABLE
mass
35.45
Cl
chlorine
Atomic #
17
Squares of the Periodic Table
VI. ORGANIZATION OF THE
PERIODIC TABLE
A. PERIODS
1. Definition---a horizontal row of elements on the
Periodic Table
--also called a “Series”
2. Energy levels and periods---the number of the period is equal to the
number of “rings” of electrons around the atom
**How many energy levels are in each element in Period 5?
B. GROUPS
1. Definition---a vertical column of elements on the Periodic
Table
--also called a “Family”
2. Valence electrons and group number---each element within a group has the same
number of valence electrons
--In general, the group number is equal to the
number of valence electrons
--For group numbers greater than 10, the number
of valence electrons is the ones place
B. GROUPS
**How many valence electrons are
in Group 2 elements?
**How many valence electrons are
in Group 16 elements?
3. CLASSIFYING THE ELEMENTS
a. Alkali Metals--
 Group 1 elements except Hydrogen.
 Most reactive metals on the Table.
 Have 1 valence electron.
b. Alkaline Earth Metals- Group 2 elements.
 Very active metals.
 Have 2 valence electrons.
c. Transition Metals- Groups 3-11 elements.
 Typically less reactive than Alkali and
Alkaline Earth Metals.
Produce colored solutions.
d. Halogens- Group 17 elements.
 Most nonmetallic elements
on the table.
 Have 7 valence electrons
e. Noble Gases- Group 18 elements.
 Extremely unreactive.
 Often called “inert”.
 Have 8 valence electrons except
He which has only 2.
f. Two Rows at the Bottom--
 Lanthanide Series-Elements 57 – 71.
 Actinide Series-Elements 89 - 103
VII. PERIOIDIC TRENDS
•As we can see, elements are grouped on the
Periodic Table according to their physical and
chemical properties as well as their electron
configurations.
•This creates the periodic repetition on the table,
and allows us to see certain trends in these
properties.
Trends on the Table
• Atomic radius
• Ionization energy
• Electronegativity
• Each of these show trends as you move
across a period AND down a group
Major Element Grouping
• The combination of periodic characteristics
creates three broad categories of elements
on the table:
• Metals
• Nonmetals
• Metalloids
Major Element Grouping
• Described in relationship to the staircase
that runs on the right-hand side of the table
• Elements to the RIGHT of the staircase =
NONMETALS
• Elements to the LEFT of the staircase =
METALS
• Elements touching staircase (except Al) =
METALLOIDS
F. Metallic and Nonmetallic Properties
Can help us characterize an element simply
by knowing its placement on the PT
Metals
• Lose electrons easily to get to "magic
number" of 8
• "Metals are losers"
• Losing electrons makes them form an ION
= charged atom
• Most metallic elements = lower left of table
REVIEW:
What is an Ion?
An atom that has lost or gained electrons and thus
has acquired a charge.
Cation-A positively charged atom
PLUSSY CATS!!
Nonmetals
• Gain electrons easily to get to "magic
number" of 8
• Nonmetals are "gainers"
• Most non-metallic elements - upper right
side of table
Anion-A negatively charged atom
"Cat chaser"