CEM 137

1
CEM 137

• Chapter 2

2
Quiz 2

• 1. A patient has a temperature of 102 oF. What
  is this temp in oC?
• 2. What is 52.0 oC in oF?
• 3. An object has a mass of 1.31 x 107 mg. What
  is this mass in grams?

3
Atomic Weight

• Atomic Weight is the weighted average of all
  isotopes for an element.
• Ex The element gallium exists as two isotopes
  gallium-69 with an abundance of 60.16 and
  gallium-71 with an abundance of 39.84. What is
  galliums atomic weight?

4
The Periodic Table

• The periodic table is probably the most useful
  and predictive tool in all of chemistry. It
  consists of groups and periods.
• Groups Vertical Columns
• Periods Horizontal Rows

5
Periodic Table

• Metals Left side, metallic luster, conduct heat
  and electricity, ductile and malleable, react by
  losing e-.
• Nonmetals Right side, dull luster, brittle,
  react by gaining or sharing electrons.
• Semimetals/metalloids On line between metals
  and nonmetals, have properties of both metals
  and nonmetals

6
Periodic Table

• Alkali Metals (Group IA or 1)
• Alkaline Earth Metals (Group IIA or 2)
• Halogens (Group VIIA or 17)
• Noble Gases (Group VIIIA or 18)

7
The Mole

• Mole
• a counting number
• 6.02 x 1023

8
Atomic Weight Again

• The Atomic Weight is the mass in grams of 1 mol
  of an element.
• Record Atomic Weights to the nearest 0.1 g/mol.