Chemical Compounds

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Chemical Compounds

• Chapter 19

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The Octet Rule

• Elements will react by gaining or losing
  electrons so as to acquire the stable electron
  structure of a noble gas, usually eight valence
  electrons.
• Or
• atoms react in a way to fill their outer energy
  level with electrons(8)
• atoms will bond in a way to accomplish this
• ions will form to accomplish this

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Chemical BondingA marriage between atoms

• Chemical Bond a force that holds together the
  atoms in a compound
• - losing, gaining or sharing electrons are all
  forms of bonding
• Atoms of different elements will bond to form
  compounds.

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Types of Chemical Bonds

• Bond, James Bond infamous 007, but not chemical
• IONIC BONDS the attraction between ions of
  opposite charge in an ionic compound
• occurs between a Metal and a Non-Metal
• Ion a positively or negatively charged atom
• results from the electrical attraction between
  large numbers of cations and anions

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• Covalent Bonding chemical bonding that results
  from the sharing of electron pairs between two
  atoms
• - occurs between two Non-Metals
• In many compounds the atoms are covalently bound
  together to form a molecule.
• Molecule an electrically neutral group of atoms
  that act as a unit

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Why Atoms Combine

• Atoms have a natural tendency to become stable.
• - in order to do this they form compounds
• Compounds substance made from two or more
  elements which has properties unlike those to the
  elements.

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Types of Compounds

• Molecular compound compounds that are composed
  of molecules - many exist as gases or liquids at
  room temp.
• composed of two or more non-metals
• Ex Water, Carbon Dioxide
• Ionic compound compounds that are composed of
  positive cations and negative anions.
• formed by a metal and a non-metal
• Ex Sodium Chloride(table salt

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Electronegativity

• the tendency for an atom of an element to attract
  electrons when they are chemically combined with
  another element.
• On the Periodic Table
• increases from left to right
• decreases from top to bottom

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• Bonds are usually never 100 covalent or 100
  ionic, they are a combination of them
• The larger the difference in electronegativity
  the more Ionic the bond
• The smaller the difference in electronegativity
  the more covalent the bond

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Electron Dot Diagrams

• What are they?
• a very simple way of showing an elements valence
  electron configuration
• An electron configuration notation in which only
  the valence electrons of an atom of a particular
  element shown, indicated by DOTS placed around
  the elements symbol

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How to Write Dot Diagrams

• Write the elements symbol
• Place dots around the symbol just like they fill
  orbitals
• 4 sides 4 orbitals
• Two dots per side two electrons per orbital

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Oxidation State

• How many electrons are lost, gained or shared
  when bonding occurs.
• We can use the Periodic table to help predict
  what the Oxidation State for a particular element
  will be.

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