Periodic Table

1 / 51

# Periodic Table - PowerPoint PPT Presentation

Periodic Table. Larry Scheffler Lincoln High School. The Periodic Table-Key Questions. What is the periodic table ? What information is obtained from the table ? How can elemental properties be predicted based on the Periodic Table ?.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Periodic Table' - tegan

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Periodic Table

Larry Scheffler

Lincoln High School

The Periodic Table-Key Questions
• What is the periodic table ?
• What information is obtained from the table ?
• How can elemental properties be predicted based on the Periodic Table?
The development of the periodic table brought a system of order to what was otherwise an collection of thousands of pieces of information

The periodic table is a milestone in the development of modern chemistry. It not only brought order to the elements but it also enabled scientists to predict the existence of yet undiscovered

elements.

Periodic Table
Early Attempts to Classify Elements
• Classified elements in sets of three having similar properties.
• Found that the properties of the middle element were approximately an average of the other two elements in the triad.

Note: In each case, the numerical values for the atomic mass and density of the middle element are close to the averages of the other two elements

Newland’s Octaves -1863
• John Newland attempted to classify the then 62 known elements of his day.
• He observed that when classified according to atomic mass, similar properties appeared to repeat for about every eighth element
• His Attempt to correlate the properties of elements with musical scales subjected him to ridicule.
• In the end his work was acknowledged and he was vindicated with the award of the Davy Medal in 1887 for his work.
Dmitri Mendeleev

Dmitri Mendeleev is credited with creating the modern periodic table of the elements.

He gets the credit because he not only arranged the atoms, but he made predictions based on his arrangement which were shown to be quite accurate.

Mendeleev’s Periodic Table
• Mendeleev organized all of the elements into one comprehensive table.
• Elements were arranged in order of increasing mass.
• Elements with similar properties were placed in the same row.
Mendeleev’s Periodic Table

Mendeleev left some blank spaces in his periodic table. At the time the elements gallium and germanium were not known. He predicted their discovery and estimated their properties

Periodic Table

The Periodic Table has undergone several modifications before it evolved in its present form. The current form is usually attributed to Glenn Seaborg in 1945

Periodic Table Expanded View
• The Periodic Table can be arranged by energy sub levels The s-block is Group IA and & IIA, the p-block is Group IIIA - VIIIA. The d-block is the transition metals, and the f-block are the Lanthanides and Actinide metals
• The way the periodic table usually shown is a compressed view. The Lanthanides and actinides (F block)are cut out and placed at the bottom of the table.
PeriodicTable: Metallic Arrangement
• Layout of the Periodic Table: Metals vs. nonmetals

Nonmetals

Metals

The Three Broad Classes Are Main, Transition, Rare Earth
• Main (Representative), Transition metals,
• lanthanides and actinides (rare earth)
• Nonmetals, Metals, Metalloids, Noble gases
Periodic Table: The electron configurations are inherent in the periodic table
• B
• 2p1

H

1s1

He

1s2

F

2p5

Be

2s2

B

2p1

C

2p2

N

2p3

Ne

2p6

O

2p4

Li

2s1

Na

3s1

Mg

3s2

Cl

3p5

Si

3p2

S

3p4

Ar

3p6

Al

3p1

P

3p3

K

4s1

Ca

4s2

Zn

3d10

As

4p3

Be

4p5

V

3d3

Mn

3d5

Fe

3d6

Co

3d7

Sc

3d1

Ti

3d2

Ga

4p1

Ge

4p2

Se

4p4

Cr

4s13d5

Kr

4p6

Ni

3d8

Cu

4s13d10

Sr

5s2

Rb

5s1

Nb

4d3

Ru

4d6

Rh

4d7

Mo

5s14d5

Cd

4d10

Sn

5p2

I

5p5

Xe

5p6

Zr

4d2

Tc

4d5

Y

4d1

In

5p1

Sb

5p3

Te

5p4

Ni

4d8

Ag

5s14d10

Hf

5d2

Cs

6s1

Ta

5d3

Re

5d5

Os

5d6

Ir

5d7

W

6s15d5

La

5d1

Rn

6p6

At

6p5

Ni

5d8

Ba

6s2

Hg

5d10

Tl

6p1

Pb

6p2

Bi

6p3

Po

6p4

Au

6s15d10

Mt

6d7

Bh

6d5

Hs

6d6

Fr

7s1

Rf

6d2

Ra

7s2

Db

6d3

Sg

7s16d5

Ac

6d1

Periodic Table Organization------ Groups or Families

Vertical columns in the periodic table are known as groups or families The elements in a group have similar electron configurations

Periodic Table Organization ---- Periods

Horizontal Rows in the periodic table are known as Periods The Elements in a period undergo a gradual change in properties as one proceeds from left to right

Periodic Properties
• Elements show gradual changes in certain physical properties as one moves across a period or down a group in the periodic table. These properties repeat after certain intervals. In other words they are PERIODIC

Periodic properties include:

-- Ionization Energy

--Electronegativity

-- Electron Affinity

Trends in Ionization Energy

Ionization energy is the energy required to

Remove an electron from an atom

• Ionization energy increases across a period because the positive charge increases.
• Metals lose electrons more easily than nonmetals.
• Nonmetals lose electrons with difficulty (they like to GAIN electrons).
Trends in Ionization Energy
• The ionization energy increases UP a group
• Atoms near the top of a group are effected less by the Shielding Effect.
Electronegativity

Electronegativity is a measure of the ability of an atom in a molecule to attract electrons to itself.

This concept was first proposed by Linus Pauling (1901-1994). He later won the Nobel Prize for his efforts

Periodic Trends: Electronegativity
• In a group: Atoms with fewer energy levels can attract electrons better (less shielding). So, electronegativity increases UP a group of elements.
• In a period: More protons, while the energy levels are the same, means atoms can better attract electrons. So, electronegativity increases RIGHT in a period of elements.
The Electron Shielding Effect
• Electrons between the nucleusand the valence electrons repel each other making the atom larger.
• The radius increases down a group.
• Because electrons are added further from the nucleus, there is less attraction. This is due to additional energy levels and the shielding effect. Each additional energy level “shields” the electrons from being pulled in toward the nucleus.
• The radius decreases on going across a period.

The radius decreases across a period owing to increase in the positive charge from the protons. Each added electron feels a greater and greater + charge because the protons are pulling in the same direction, where the electrons are scattered.

Large

Small

Core Charge
• The concept of core charge can be used to better understand trends in atomic radii.
• Core charge = nuclear charge (ie: number of protons) – number of inner-shell electrons.
• Eg: Na (s) 11p – 10e = +1
Core Charge
• The greater the core charge, the greater the attraction of protons to electrons.
• greater core charge means SMALLER atomic radii.
• Core charge increases across period 3 so atomic radii decreases.
Cations

Cations (positive ions) are smaller than their corresponding atoms

Ion Sizes

Does the size go up or down when gaining an electron to form an anion?

+

+

Li

, 78 pm

2e and 3 p

Forming a cation.

• CATIONS are SMALLER than the atoms from which they come.
• The electron/proton attraction has gone UP (increased core charge) and so the radius DECREASES.

Li,152 pm

3e and 3p

Positve ions or cations are smaller than the corresponding atoms.

Cations like atoms increase as one moves from top to bottom in a group.

Anions

Anions (negative ions) are larger than their corresponding atoms

-

-

F 64 pm

F

, 133 pm

9e- and 9p+

10 e- and 9 p+

• ANIONS are LARGER than the atoms from which they come.
• The electron/proton attraction has gone DOWN (core charge decreases) and so size INCREASES.
• Trends in ion sizes are the same as atom sizes.

Forming an anion.

Negative ions or anions are larger than the

corresponding atoms.

Anions like atoms increase as one moves from top to bottom in a group.

Ionic Radius for an Isoelectronic Group

Isoelectronic ions have the same number of electrons.

The more negative an ion is the larger it is and vice versa.

The Periodic Table--Summary

The periodic table is a classification system. Although we are most familiar with the periodic table that Seaborg proposed more than 60 years ago, several alternate designs have been proposed.