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Periodic Table Periods

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Periodic Table Periods Atoms in a period have the same number of energy levels. Periodic Table Groups Many groups have special names that describe their characteristics. – PowerPoint PPT presentation

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Title: Periodic Table Periods


1
Periodic Table Periods
  • Atoms in a period have the same number of energy
    levels.

2
Periodic Table Groups
  • Many groups have special names that describe
    their characteristics.
  • Atoms in a group have same number of valence
    electrons so they behave similarly.
  • Roman numerals represent the number of valence
    electrons.

3
Terms to Know
  • Cations refer to the elements that lose electrons
    and form a positive ion.
  • Anions refer to the elements that gain electrons
    and form a negative ion.

4
Alkali Metals
  • All form 1 cations
  • Very reactive with water
  • Highly reactive in general

5
Alkaline Earth Metals
  • All form 2 Cations
  • Somewhat reactive with water
  • Highly reactive with acids.

6
Halogens
  • All form -1 Anions
  • Aggressive Oxidizers
  • Used in Halogen bulbs.

7
Noble Gases
  • Non-reactive
  • Fulfilled Octet Rulehave 8 valence electrons in
    the outer most energy level and considered stable.

8
Other Groups
  • Group 13 (IIIA) Boron Family
  • Form 3 Cations
  • Group 14 (IVA) Carbon Family
  • Form 4 Cations or Anions
  • Group 15 (VA) Nitrogen Group
  • Form -3 Anions
  • Group 16 (VIA) Oxygen Family
  • Form -2 Anions

9
Periodicity
  • When elements are arranged in order of increasing
    atomic number, there is a periodic repetition of
    their physical and chemical properties.
  • An important consequence is that the elements
    with similar chemical and physical properties end
    up in the same column.
  • Trends on the periodic table govern how elements
    behave chemically.
  • All elements are unique, but follow these
    trends.generally.

10
Atomic Size/Atomic Radius
  • Atomic radius is ½ the distance between the
    nuclei of identical atoms that are bonded
    together.
  • Group Trend size INCREASES as you move down
    (added energy levels electrons farther from
    nucleus).
  • Period Trend size DECREASES as you move left to
    right (more protons and electrons pulling harder
    on one another).
  • Due to increasing energy levels and shielding by
    inner electrons. Inner electrons shield the
    outermost electrons from the nucleus.

11
Atomic Size Cont.
12
Examples
  • Which atom has the larger radius?

Be or Ba Ca or Br
Ba Ca
13
Ionic Size/Ionic Radius
  • Ionic Radius is the relative size of the most
    common ion of an atom.
  • Group Trend INCREASE top to bottom due to
    shielding.
  • Cations are always smaller than their neutral
    atom
  • Loss of electrons increase attraction
  • Anions are always bigger than their neutral atom.
  • Gain of electrons decrease attraction
  • Period Trend DECREASE left to right.

14
Electronegativity
  • Electronegativity is a measure of the ability of
    an atom in a chemical compound to attract
    electrons when they are chemically combined with
    atoms of another element.
  • Group Trend DECREASE as you move down due to
    increasing number of energy levels.
  • Period Trend INCREASE from left to right right
    due to switch from cat ions to anions.
  • Fluorine has an electronegativity of 4.0,
    everything below and to the left is lower.

15
Electronegativity
16
Electronegativity
17
Ionization Energy
  • Ionization Energy is the energy required to
    overcome the attraction of the protons and remove
    one electron from a neutral atom of an element .
  • The energy required to remove the 1st outermost
    electron is call the 1st ionization energy. And
    the energy for the 2nd outermost electron to be
    removed is called 2nd ionization energy.
  • Atoms may have 2nd or 3rd ionization energies
    depending on number of valence electrons and
    adherence to octet rule.

18
Ionization Energy
  • Group Trend ionization energy DECREASES as you
    move down (electrons further from the pull of the
    nucleus are easier to remove).
  • Period Trend ionization energy INCREASES as you
    move left to right (greater attraction of the
    nucleus for electrons).

19
Ionization Energy Cont.
20
Examples
  • Which atom has the higher 1st I.E.?

N or Bi Ba or Ne
N Ne
21
Summary of Periodic Trends
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