Bell ringer

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Bell ringer

• 2nd period
• (Molly, Timmy)(Kiersten, Michael)(Caitlin,
  John)(Kaitlyn, Ariel)( Morgan, Sherman)
  (Cheyenne, Emily)(Racheal, Courtney M)(Jenna,
  Courtney L)
• 8th period
• (Kaitlyn, Destanie)(Tim, Morgan)(Jen, Chelsey)
  (William, Hannah)

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Electronegativity

• Electronegativity is a chemical property that
  describes the ability of an atom to attract
  electrons (or electron density) towards itself
• Electronegative atoms love electrons

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Polar bonds

• Polar covalent bonds are
• When electrons between two atoms are not shared
  equally
• Nonpolar covalent bonds are
• When electrons between two atoms are shared
  equally

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Polar examples

• HCl
• H2O

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How to tell if something is polar

• Use electronegativity
• the difference in electronegativity will tell
  you how polar a bond is.
• E.g. HF F2

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Bell ringer

• List the following bonds in order of polarity?
• HF HCl HBr NaF

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Polarity

• Polar molecules are
• Molecules that have one end of the molecule more
  slightly negative then its other end.
• A molecule that has two poles are called Dipoles
• Not all molecules with polar bonds are polar
  molecules

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Nonpolar examples

• CCl4
• CO2

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Intermolecular forces

• Intermolecular forces are attractions between
  molecules that are weaker than ionic and covalent
  bonds
• There are several different types of these
  forces. Two main types are van der Waals forces
  and hydrogen bonds

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Van der Waals

• Van der Waals forces are named after a Dutch
  chemistry. There are two types of van der Waals
  forces, Dispersion forces, and dipole
  interactions.
• Dispersion forces are the weakest of all
  molecular forces and are caused by the motion of
  the electrons.

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Dipole interactions
These occur when polar molecules are attracted to
each other. The positives will be attracted to
the negatives and negatives will be attracted to
the positives
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Hydrogen bonds

• When a hydrogen is bonded covalently to a very
  electronegative atom it leaves its protons
  unshielded.
• These protons will then from small bonds with
  lone pairs of electrons on a nearby atom.

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Other Lewis stuctures

• The most common way to draw Lewis structures is
  with dots but there is a different way.
• A bonding pair of electrons can be represented by
  a line (-)
• -
• E.g. NH3 CH3OH

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• Practice using lines instead of dots for the
  following Lewis structures.
• HF CCl4 C2H4

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