Chapter 5: Atoms

1
Chapter 5 Atoms Bonding

• Stuff we still need to cover!

2
Ionic Bonds (5-2)

• Polyatomic ions - ions that are made of more than
  one atom. poly means many. The group of atoms
  act as a unit. Ex. Bicarbonate HCO3- (a
  component of baking soda)
• Subscript - Tells you the ratio of elements that
  comprise the compound. In the above polyatomic
  ion there is 1 H to 1 C to 3
  Oxygen atoms.

3
Naming ionic compounds

• In ionic compounds, the name of the positive ion
  comes first, then the negative ion. (metal then
  non-metal)
• If the negative ion is a single element the name
  changes to ide ex. MgO is Magnesium Oxide (not
  Oxygen)
• If the negative ion is polyatomic the name
  usually ends in -ate or -ite
• Ex. Ca(NO3)2 calcium nitrate

4
Covalent Bonds 5-3

• Polar bonds - A covalent bond in which electrons
  are shared unequally. This causes one side of
  the molecule to have a positive charge and the
  other to have a negative charge. Water is an
  example.
• Nonpolar bonds - A covalent bond in which the
  electrons are shared equally. There is no
  resulting charge on the molecule. Carbon
  dioxide is an example.

5
Covalent Bonds

• The number of covalent bonds that a non-metal
  atom can form is equal to the number of electrons
  it needs to get to 8.
• A double bond forms when atoms share two pairs of
  electrons.
• A triple bond forms when atoms share three pairs
  of electrons. (see overhead)

6
Bonding in Metals 5-4

• An alloy is a mixture of 2 or more elements, at
  least one of which is a metal. Ex. Brass is a
  mixture of copper and zinc. Fe,C,Ni, and Cr
  Stainless Steel
• Metal atoms combine in regular patterns with the
  positive ions packed together and the electrons
  bobbing and weaving around them. (forming a sea
  of electrons)

7
Metallic Properties

• The sea of electrons model of metallic bonding
  explains metallic properties, such as
• Malleability, ductility, luster, high electrical
  conductivity, and high thermal (heat) conductivity