Periodic table
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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 ?.

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Periodic table

Periodic Table

Larry Scheffler

Lincoln High School


The periodic table key questions

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?


Periodic table1

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

Early Attempts to Classify Elements

  • Dobreiner’s Triads (1827)

    • 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.


Dobreiner s triads

Dobreiner’s Triads

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

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

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’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 table1

Mendeleev’s Periodic Table


Mendeleev s periodic table2

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 table2

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

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.


Periodic table metallic arrangement

PeriodicTable: Metallic Arrangement

  • Layout of the Periodic Table: Metals vs. nonmetals

Nonmetals

Metals


The three broad classes are main transition rare earth

The Three Broad Classes Are Main, Transition, Rare Earth

  • Main (Representative), Transition metals,

  • lanthanides and actinides (rare earth)


Reading the periodic table classification

Reading the Periodic Table: Classification

  • Nonmetals, Metals, Metalloids, Noble gases


Periodic table the electron configurations are inherent in the periodic table

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

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

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

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

-- Atomic Radius

-- Ionic Radius


Trends in ionization energy

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 energy1

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.


Ionization energies

Ionization Energies


Ionization energies are periodic

Ionization Energies are Periodic


Electronegativity

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

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.


Trends in electronegativity

Trends in Electronegativity


Electronegativity1

Electronegativity


Electronegativity2

Electronegativity


The electron shielding effect

The Electron Shielding Effect

  • Electrons between the nucleusand the valence electrons repel each other making the atom larger.


Atomic radius

Atomic Radius

  • 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.


Atomic radius1

Atomic Radius

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

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 charge1

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.


Atomic radius2

Atomic Radius


Atomic radius3

Atomic Radius


Trends in ion sizes

Trends in Ion Sizes

Radius in pm


Cations

Cations

Cations (positive ions) are smaller than their corresponding atoms


Ion sizes

Ion Sizes

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


Ionic radius

+

+

Li

, 78 pm

2e and 3 p

Ionic Radius

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


Ionic radius for cations

Ionic Radius for Cations

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

Anions (negative ions) are larger than their corresponding atoms


Ionic radius anions

-

-

F 64 pm

F

, 133 pm

9e- and 9p+

10 e- and 9 p+

Ionic Radius-Anions

  • 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.


Ionic radii for anions

Ionic Radii for Anions

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

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.


Summary of periodic trends

Summary of Periodic Trends


Properties of the third period oxides

Properties of the Third Period Oxides


Properties of the third period chlorides

Properties of the Third Period Chlorides


The periodic table summary

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.


Alternate periodic tables

Alternate Periodic Tables


Alternate periodic tables ii

Alternate Periodic Tables II


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