Chemical Compounds

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Chemical Compounds
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Stability and Reactivity

• Stability Complete Last Orbital
• (like the noble gases).
• How is it done?
• By losing or gaining electrons.
• When an atom loses or gains electrons it becomes
  an ion.
• The easiest it is to lose or gain electrons, the
  more reactive is the element.

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O
Ne
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Metals Electron Givers

• Metals are more likely to lose electrons.
• They form positive ions called cations.
• Reactivity of metals can be predicted in the
  following way 
• As we go down in a family, the reactivity
  increases because the valence electrons are
  farther away from the nucleus.

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Non-Metals Electron Takers

• Non-metals are more likely to gain electrons.
• They form negative ions called anions.
• Reactivity of non- metals can be predicted in the
  following way 
•   As we go down in a family, the reactivity
  decreases because the attraction of the nucleus
  is reduced

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Reactivity TrendMetals Non-metals
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Bohrs diagrams of ions

O
O
Oxygen atom Oxygen ion O O2-
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Compound Formation

• There are three ways for an atom to become more
  stable 
• 1.  Lose electrons
• 2.  Gain electrons
• 3.  Share electrons

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Types of Compound

• There are two main types of chemical compounds
• Ionic Compounds
• and
• Molecular Compounds

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Ionic Compounds

• Ionic Bond Attraction between cations and
  anions.
• Electrons are transferred.

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Ionic Compounds
Br
K
Br
K
1
1 -
KBr

Br
K
Br
K
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Molecular Compounds

• Covalent Bond Attraction between non-metal
  atoms.
• Electrons are shared.

H
O
H
O
H
H
H20
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Properties of Compounds

• Ionic Molecular
• Ionic network Molecule
• With Charge No charge

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Properties of Compounds

• Ionic Molecular

High melting point Low melting point (All solid
at 25C)
Good conductors Bad conductors in water
solution in water solution
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Diatomic Elements

• Hydrogen H2 These elements
• Nitrogen N2 form molecules
• Oxygen O2 of two atoms.
• Fluorine F2
• Chlorine Cl2
• Bromine Br2
• Iodine I2

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Polyatomic Ions

• Some elements combine to form small groups acting
  like a single element.
• They carry a charge and can combine with other
  elements to forme a compounds.
• Most of them act like non-metals as electons
  takers.