Lecture Notes: Electrical Nature of Matter

Introduction to Electrical Nature of Matter

• Matter has mass and takes up shape.
• Atoms: Composed of protons (positive charge) and electrons (negative charge).
• Movement of electrons causes matter to be charged (positive or negative).

Static Electricity and Electrostatics

• Static Electricity: Charge remains on a substance.
  • Example: Rubbing a balloon and sticking it on a wall.
• Electrostatics: Study of static charges.

Charged Objects

• Negatively Charged: More electrons than protons.
• Positively Charged: More protons than electrons.
• Neutral: Equal protons and electrons.

Law of Charges

1. Like Charges Repel: Similar to magnets with the same pole.
   • Positively charged objects repel each other.
   • Negatively charged objects repel each other.
2. Opposite Charges Attract: Positive attracts negative and vice versa.
3. Charged Attract Neutral: A charged object can attract a neutral object.

Methods of Charging Objects

1. Charging by Friction: Two objects rubbed together transfer electrons.

   • Example: Balloon and hair.
   • Use of Electrostatic Series to predict charge tendency of materials.
     • Materials with strong electron hold become negatively charged.
     • Materials with weak electron hold become positively charged.
   • Conductors (e.g., gold, platinum) allow electron passage.

2. Charging by Contact: A charged object touches a neutral object, passing on the charge.

   • Example: Touching a doorknob after walking on carpet.
   • Illustrated through an electroscope with a pith ball.
     • Transfer of negative charge leads to a negatively charged pith ball.
     • Transfer of positive charge leads to a positively charged object.

3. Charging by Induction: A charged object is near a neutral object, causing induced charge separation.

   • Does not involve direct contact.
   • Example: Lightning causing induction between cloud and ground.
   • Induces a temporary opposite charge.

Summary

• Understanding the nature of electric charge is essential in chemistry.
• Methods of charging include friction, contact, and induction.
• Application examples: Everyday phenomena like static electricity, lightning.