The Periodic Table and Its Trends

1
The Periodic Table and Its Trends

• Chapters 6 10

2
The need for organization

• How do you know where to find various products in
  a supermarket?
• Arranged by food typebreads, produce, dairy,
  meats, etc.
• This allows for easy comparing and finding of
  products.

3
Relation to elements.

• Chemical elements are arranged in groups that
  have similar chemical and physical properties.

4
Development of the Periodic Table

• Johann Dobereiner-German chemist
• Found that the properties of the metals Calcium,
  Barium, and Strontium were very similar and that
  the atomic mass of Strontium was in between the
  other 2.
• Grouped into a triad
• John Newlands-English Chemist
• Arranged elements according to their atomic
  masses in octaves.
• Repetition of properties every 8th element.

5
Development-Dmitri Mendeleev

• Properties of elements were a function of their
  atomic masses and repeated in a periodic fashion.
• 1869-First Periodic Table with 8 columns along
  with blank spaces
• Arranged the columns so that elements with the
  most similar properties were arranged side by
  side.
• Blank spaces for undiscovered elements.
• He even predicted the properties of these unknown
  elements and was pretty close.

6
The problem

• Tellerium and Iodine were in the wrong
  column-their properties were NOT similar to the
  column they were in.
• Similar to the element in an adjacent column.
• Mendeleev thought it was because the masses were
  inaccurately measured and just switched them to
  the next column.

7
Henry Moseley

• Used X-ray experiments in 1913 to show that the
  nucleus of each element has an integral positive
  charge-
• The Atomic Number
• Periodic Table was revised according to his
  findings.

8
The Periodic Law

• Properties of elements are a periodic function of
  their Atomic Numbers.
• Sothis means that when you arrange the elements
  according to their atomic numbers, you see a
  repetition of their physical and chemical
  properties.

9
Modern Periodic Table
Atomic Number
Li
3
6.941
Atomic Mass
10
Arrangement

• Elements are arranged in rows or periods
  (horizontal arrangement).
• 7 periods in all.
• Vertical Columns are called groups or families.
• Elements that have similar chemical and physical
  properties end up in the same column.
• Elements with similar electron configurations are
  placed in the same column. They can also be
  listed in order of increasing principal quantum
  numbers.

11
Activity Creating your own Periodic Table

• Using the cards provided and the information just
  provided, place these cards in periods and
  groups.
• After you have them arranged, write down the
  common chemical and physical properties of each
  group.

12
Electron Configurations

• Way in which electrons are arranged around the
  nuclei of atoms.
• Uses the
• Aufbau Principle
• Pauli Exclusion Principle
• Hunds Rule

13
Electron Configuration

• Aufbau Princple Electrons enter orbitals of
  lowest energy first.

14
Energy Levels

• Below is a chart to help you know which orbitals
  will fill up first.

7s 7p 6s 6p 6d 5s 5p 5d 5f 4s 4p 4d
4f 3s 3p 3d 2s 2p 1s
Increasing Energy Level
15
Pauli Exclusion Principle

• An atomic orbital may describe at most 2
  electrons
• So for the 1s orbital, there can be at most 2
  electrons located here.

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Electron Configurations for Hydrogen

• Hydrogen has Z1
• Fill the lowest energy level first.
• Electron Conf. equals 1s1
• The orbital contains less than 2 electrons
  occupies the lowest energy level possible.

7s 7p 6s 6p 6d 5s 5p 5d 5f 4s 4p 4d
4f 3s 3p 3d 2s 2p 1s
Increasing Energy Level
17
Try Helium

• What is Heliums
• Atomic ?
• Start w/ orbital in the lowest Energy level.
• Remember to only put 2 electrons in each orbital.

7s 7p 6s 6p 6d 5s 5p 5d 5f 4s 4p 4d
4f 3s 3p 3d 2s 2p 1s
Increasing Energy Level
18
Try Helium

• Heliums Z2
• So the lowest energy level is 1s.
• You can put both electrons in this orbital.
• Electron conf. 1s2

7s 7p 6s 6p 6d 5s 5p 5d 5f 4s 4p
4d 4f 3s 3p 3d 2s 2p 1s
Increasing Energy Level
19
Practice Write the electron configurations for
the following

• Lithium
• Beryllium
• Boron

1s22s1
1s22s2
1s22s22p1
20
Hunds Rule

• When electrons occupy orbitals of equal energy
  (for example, the three 2p orbitals), then 1
  electron enters each orbital until all the
  orbitals contain 1 electron with parallel spins.
  After each equal energy orbital has 1 electron,
  an electron of opposite spin is filled in.

3px
3py
3pz
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Relation of orbitals to periodic Table
1s
1s
2s
2p
3s
3p
4s
4p
3d
5s
5p
4d
6s
6p
5d
7s
6d
4f
5f
22
Activity

• Complete the worksheet for extra practice in
  completing electron configurations.
• Answer the questions at the bottom.

23
Importance of Electrons

• The chemical and physical properties of an
  element are determined by electron
  configurations.
• The outer energy level is considered full when
  the highest energy s and p orbitals are filled
  with electrons.
• When they are filled, they have 8 outer electrons
  (except He and H). These outer electrons are
  called the valence electrons.
• Filled energy sublevels are more stable or less
  reactive than partially filled levels.

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Octet Rule

• When an atom has 8 outer electrons (the highest
  energy s and p orbitals filled), an atom is
  rendered unreactive.
• Helium is full with 2 valence electrons.
• These elements are called noble gases and make up
  Group VIIIA. Noble gases undergo few chemical
  reactions.

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Metals vs. Nonmetals

• Metals are located on the left side of the
  periodic table.
• General properties hard, shiny, conduct heat
  and electricity well
• Metals generally only have a few electrons in the
  outer level.
• Link to Periodic table

27
Metals

• The elements in Group 1 (IA) except for Hydrogen
  are called the Alkali metals.
• The elements in Group 2 (IIA) are called the
  Alkaline Earth metals.
• The elements in groups 3-12 are called the
  transition metals.
• The Lanthanide and Actinide Series are called
  Inner Transition metals.

28
Nonmetals

• Located on the right side of the Periodic Table.
• General Properties include generally gases or
  brittle solids at room temperatures. If solid,
  they are generally dull and good insulators
• Have more electrons in the outer level of
  electrons. Periodic Table

29
Nonmetals

• Again, Noble Gases are located in group 18 or
  VIIIA
• The Halogens consist of Group 17 or Group VIIA

30
The Metalloids

• The heavy stair step line divides the metals and
  nonmetals. These elements in the middle are
  considered metalloids. Metalloids are elements
  that have intermediate properties between a metal
  and a nonmetal.
• General rule elements with 3 or fewer electrons
  in the outer level are considered metals.
  Elements with 5 or more electrons in the outer
  level are considered to be nonmetals.