Compounds, Chemical Formulas,

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Compounds, Chemical Formulas, Bonding
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Unstable Atoms

• In order for an atom to be stable, it must have
  at least 8 valence electrons in its outermost
  energy level
• If an atoms outermost energy level is the first,
  then it must have 2 valence electrons (Hydrogen
  Helium)
• In order to become stable, atoms react with other
  atoms by forming chemical bonds
• Most atoms are naturally unstable, and are always
  found bonded with other atoms

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The Noble Gases

• Group 8 elements
• Have full outer levels
• Dont form bonds

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When Atoms Stick Together

• If bonded atoms are all the same type, the
  substance is considered an element
• EX. O2 2 bonded oxygen atoms
• If bonded atoms are 2 or more different types,
  the substance is considered a compound
• EX. H2O 2 hydrogen atoms bonded to 1 oxygen
  atom
• Molecule smallest unit of most chemical
  compounds that retains the properties of that
  compound

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Chemical Formulas

• Chemical formulas give 2 pieces of information
  about a substance
• What types of atoms make up the substance
• How many atoms of each type
• EX. C6H12O6 is the formula for the sugar glucose
  1 molecule of glucose contains
• 6 carbon atoms
• 12 hydrogen atoms
• 6 oxygen atoms

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Ionic Bonds What are they?

• Ionic bond a bond formed by the attraction
  between positive and negative ions
• Ion an atom that gains or loses one or more
  electrons giving it a positive or negative charge
• Ionic bonds occur between metals and non-metals
• Metal atom forms the positive ion (gives e-)
• Non-metal atom forms the negative ion (takes e-)

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Ionic Bonds How do they form?

• A non-metal atom with more than 4 valence
  electrons takes electrons from a metal atom
• The non-metal becomes negative
• The metal becomes positive
• The opposite ions attract forming an ionic bond
• Ionic compounds are generally solids with high
  melting points (Ex. NaCl Salt)

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More Chemistry Humor
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Covalent Bonds What are they?

• Covalent bond A bond formed when atoms share
  one or more pairs of valence electrons in order
  to become stable
• EX. H2O
• Atoms that share more than one pair of electrons
  may form double or triple bonds
• EX. O2
• Covalent bonds form between atoms of non-metals

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Covalent Compounds

• Solids, liquids, or gases with low melting points
• Organisms are built almost entirely out of 4
  important types of covalent compounds
• Carbohydrates
• Proteins
• Lipids
• Nucleic Acids