Chemistry Lecture: Metal Activities and Reactivity

Key Concepts

• Metal Activities/Reactivity: Focus on single replacement reactions and whether a reaction occurs based on metal activity.
• Single Replacement Reactions: Involves the replacement of a metal in a compound by a free metal.

Natural Occurrence of Metals

• Metals occur naturally in two forms:
  • As an Ore: In a compound.
  • Free Metal: In a pure form.
• Less Active Metals: Usually appear as free metals (e.g., silver, gold, platinum, copper).
• More Active Metals: Usually found in compounds (e.g., alkaline metals).
• Transition Metals: Intermediate activity; some appear in compounds over time (e.g., iron, aluminum).

Activity Series

• Metals are ranked by activity; more active metals are higher on the activity series.
• Most Active Metal: Lithium.
• Least Active Metal: Gold.
• Medium Activity Metals: Aluminum, magnesium, zinc, chromium, iron.

Activity Series and Reactions

• More active metals are more willing to give up electrons, making them more reactive.
• Metals give away electrons; they are oxidized when they lose electrons.

Example Reaction

• Calcium and Gold Ion Reaction:
  • Calcium (more active) can give electrons to gold, causing gold to become a solid metal (reduction).
  • Calcium loses electrons to become calcium 2+ (oxidation).
  • Gold 3+ gains electrons to become neutral (reduction).

Concepts of Oxidation and Reduction

• Oxidation: Loss of electrons; "OIL" - Oxidation Is Losing.
• Reduction: Gain of electrons; "RIG" - Reduction Is Gaining.

Agents in Reactions

• Reducing Agent: The substance that donates electrons (Calcium in this example).
• Oxidizing Agent: The substance that gains electrons (Gold in this example).

Writing Half Reactions

• Oxidization Half Reaction: Calcium becomes calcium 2+ by releasing electrons.
• Reduction Half Reaction: Gold 3+ gains electrons to become neutral gold.

Additional Resources

• Reference to page 145 in the "Chemistry in the Community" textbook for the activity series chart.
• Digital notebook assignments with further examples and half reaction writing exercises.

General Questions

• Students are encouraged to ask questions about determining reactions and writing half reactions.