Agenda: 2/19• Warm-up: Origin of the Elements
•
• Review of Radioactive Isotopes • Half Life Calculations • Fission and Fusion
• Mole Practice
Review: Isotopes• What does the “235” in Uranium-235 mean?
• What is another way to represent the isotope Uranium -235?
• How do Carbon-12 and Carbon-14 differ?
Review: Radioactive IsotopesA radioactive isotope has an __________nucleus that
undergoes _____________ changes. - Emits particles
- 1.- 2.
- Emits energy in the form of __________ waves. - Transmutates (changes) into another element
Fill in the missing symbols & identify the type of particle emitted
Answers
• Write a balanced nuclear equation for each decay process indicated.
• a. The isotope Th-234 decays by an alpha emission. • • • • b. The isotope Fe-59 decays by a beta emission
Answers
Half life Calculations• How much of a 100g sample of an unstable isotope
remains after 25 years if the half life is 5 years?• Determine how many “half life intervals”. • Calculate the amount of original sample remaining after
each ½ life• Simplify the calculations
• 100g
Half Life Problems• How much of a 60g sample of an unstable isotope
remains after 2 days if the half life is 12 hours?
7.5 g
Half Life Problems• How much of a 20 g sample of an unstable isotope
remains after 3 sec if the half life is 0.5 seconds?
Nuclear Fission – Example: Catawba Nuclear Energy Plant – Lake Wylie
For Student notes:
Nuclear FusionExample: Sun’s (Star’s) Energy
ORIGINS OF ELEMENTReading Analysis:
Teachers' Domain: The Origin of the Elements
Teachers' Domain: The Elements: Forged in Stars
• Moles: a counting unit in chemistry• Mole calculation review & practice• Molar Mass of Compounds
Mole Flow Chart
Mole
MassGas volume
Atoms Compounds
Practice problems: Moles and Mass
• What is the mass of 0.5 moles of S?
• How many grams is equivalent to 0.137 moles of Fe?
• 4.63 mol P = ? grams P
Practice problems
• How many moles are in 84.3 grams of Si?
• 50 grams of Ne = ? moles of Ne
Mole and Atom Conversions• How many atoms of Al are in 2.5 moles?
• How many atoms of Ag are in 0.26 moles?
• How many atoms of He are in 0.0023 moles?
Moles and Volume (Gases only)• How many Liters of He are in 0.023 moles?
• How many moles are in 60 L of Neon?
Molar Mass of Compounds• NaOH H₃PO₄
• H₂O PCl₃
• MgCl₂ H₂SO₄
Mole Conversion of Compounds• How many grams are in 5 moles of CO₂?
• How many atoms are in 5 moles of CO₂?
• How many liters are in 5 moles of CO₂?