LEQ: How do molecules form from atoms?

1
LEQ How do molecules form from atoms?

• Assignment Reading 2.1, 32.1 (next unit)
• Activator electromagnetism
• The electrical and magnetic properties of matter
  are related. What happens when you place like
  ends of a magnet together?
• Predict what do you think will happen when you
  place a like charge near a like charge?
• Key terms compound, molecule, ion

2

• Protons determine the element (type of atom)
• () charge
• Neutrons - nuclear stability and decay
• no charge
• Electrons participate in electromagnetism and
  bonding
• (-) charge

3
Dozens of elements are essential to life
4

• Compounds consist of atoms of different elements
  bonded together.

• water (H2O)
• carbon dioxide (CO2) shown below
• Overlap in energy levels indicates bonding

5
Atoms share pairs of electrons in covalent bonds.

• Covalent bonds are key features of molecules
• atoms share a pair(s) of electrons.

• multiple covalent bonds possible

6
Ions form when atoms gain or lose electrons.

• Ionic bonds (compounds) form between oppositely
  charged ions.
• Weaker than covalent bonds

• positive ions cations
• negative ions anions

7
Summary

• Compare and contrast
• What are the similarities and differences between
  covalent bonds and ionic bonds?
• How does a molecule differ from an atom?