The Periodic Law

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The Periodic Law

• Chapter 9
• Carmen Alex

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9.4 Metals and Nonmetals

• Metals are solid at 25C
• Exception mercury
• Nonmetals
• Solid
• i.e. carbon, sulfur
• Liquid
• i.e. bromine
• Gaseous
• Chlorine, oxygen, nitrogen
• Metals to nonmetals -gt 51

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Metals

• Metallic luster
• Opaque
• Pliable
• Conductors
• Heat
• Electricity
• Intermediate elements
• Carbon, silicon, germanium, arsenic

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9.5 Chemical Activity

• Activity Stability
• Active elements readily combine to form compounds
• i.e. sodium
• Inactive elements have little tendency to react
  chemically
• i.e. gold
• Level of Activities
• Measure heat output from chemical reactions
• Measure energy input to separate compounds

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9.6 Families of Elements

• Active nonmetals halogens
• Active metals alkali metals
• Inactive gases inert gases

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Halogens Salt Formers

• Corrosive (fluorine)
• Odorous (bromine)
• Brilliant color (chlorine)
• NaF ZnF2 AlF3
• NaCl ZnCl2 AlCl3
• NaBr ZnBr2 AlBr3

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Alkali Metals

• Soft
• Chemically active
• Loose luster
• Liberate hydrogen from water
• Low melting points
• Combine with active nonmetals
• Bromides
• Sulfides
• Hydroxides

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Inert Gases

• Very inactive
• helium, neon, krypton, xenon, radon
• Glow in various colors

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9.7 The Periodic Table

• Elements are listed in order of atomic number
• Elements with similar chemical and physical
  properties appear at regular intervals

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Dimitri Mendeleev

• First formulated the periodic law around 1869
• Professor of chemistry at University of St.
  Petersburg
• 63 known elements

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9.8 Groups and Periods

• Horizontal periods
• Active metal
• Less active metal
• Weakly active nonmetal
• Highly active nonmetal
• Inert gas
• Vertical groups
• Similar properties

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Periods

• Transition metals
• Periods 4 and 5
• Iron, nickel, copper, gold, etc.
• Rare-earth metals
• Actinides
• Period 7

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9.9 Shells and Subshells

• Shells contain electrons with similar energies
• Electrons
• Quantum number n
• Same distance from nucleus
• Similar energies
• Orbital quantum number l
• l influences the shape of the electrons
  probability cloud
• l influences the electrons average distance for
  the nucleus
• The higher the value of l, the higher the energy
  of the electron

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9.10 Shells and Subshells

• Period 1
• 1st shell 2 electrons max.
• Period 2
• 1st shell 2 electrons max.
• 2nd shell 8 electrons max.
• Period 3
• 1st shell 2 electrons max.
• 2nd shell 8 electrons max.
• 3rd shell 8 electrons max.
• Period 4
• 1st shell 2 electrons max.
• 2nd shell 8 electrons max.
• 3rd shell 18 electrons max.
• 4th shell 8 electrons max.

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Electron Structures
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Probability Distributions
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Electron Structure

• Inert Gas Atom
• All shells and subshells are closed
• Chemically passive elements
• Hydrogen and Alkali Metal Atoms
• Have single outer electrons
• Tend to loose outer electron in chemical reactions

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Electron Structure

• Halogen Atoms
• Outer shell 1 electron short of a closed shell
• Very reactive
• Metals
• Has one or several electrons outside closed
  shells or subshells
• Combines chemically by loosing these electrons
• Nonmetals
• Needs one or several electrons to achieve closed
  shells or subshells
• Combines chemically by picking up (from metals)
  or sharing (with nonmetals) electrons

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9.11 Types of Chemical Bonds

• What holds atoms to one another?
• Electric forces act in one the following ways
• Electrons are shared (covalent bonding)
• Electrons shift to another atom (ionic bonding)
• No bond forms and no interaction occurs

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9.12 Covalent Bonding

• Sharing electron pairs
• H H
• O O
• N N
• H Cl
• H O H

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9.13 Ionic Bonding

• Electron Transfer
• NaCL
• Na2S
• CaO

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9.14 Ionic Compounds

• Metals and nonmetals combine
• NaCl
• Na looses one electron
• Cl gains one electron
• Na2S
• S gains two electrons
• 2 Na atoms loose one electron each