the periodic table and periodic law essential questions * how can the periodic table help us...

THE PERIODIC TABLE and PERIODIC LAW

Essential Questions

* How can the periodic table help us organize our chemistry knowledge?

* How can we organize all the different elements?

* 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?

B. EXAMPLES OF OTHER EVENTS THAT ARE PERIODIC--

A. DEFINITION--Happening or repeating at regular intervalsCyclic - happening in a cycle

Phases of moon Seasons Tides

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!

Giant Wall Periodic Table erectedin St. Petersburg, Russia in 1934

Why the blanks?

2. ORGANIZATION OF MENDELEEV’S TABLE

3. LEFT BLANKS

4. ORIGINAL PERIODIC LAW--

Mendeleev left spaces on the table wherehe thought undiscovered elements should go.

The physical and chemical properties of elements are periodic functions of their atomic mass.

5. MODIFICATION OF PERIODIC LAW

Mendeleev’s table not completely correct.

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 126.90Th 232.04 & Pa 231.04U 238.03 & Np 237.05

C. HENRY MOSELEY1887-1915

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

Atomic #

mass 35.45

Cl17

chlorine

Squares of the Periodic Table

VI. ORGANIZATION OF THE PERIODIC TABLE

A. PERIODS1. Definition--

2. Energy levels and periods--

--a horizontal row of elements on the Periodic Table--also called a “Series”

--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--

2. Valence electrons and group number--

--a vertical column of elements on the Periodic Table

--also called a “Family”

--each element within a group has the samenumber 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--

Actinide Series--

Elements 57 – 71.

Elements 89 - 103

VII. PERIOIDIC TRENDS•As we can see, elements are grouped on the Periodic Table according to their physical andchemical 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 simplyby 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

Cation--

What is an Ion?REVIEW:

A positively charged atom

An atom that has lost or gained electrons and thushas acquired a charge.

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"