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Section 1: Matter and Thermal Energy

Overview of States of Matter

• There are four primary states of matter: solid, liquid, gas, and plasma.

Essential Questions

• What is the kinetic theory of matter?

• How do particles move in the different states of matter?

• How do particles behave at the boiling and melting points?

Vocabulary Review

• Kinetic Energy: The energy associated with the motion of particles.

Kinetic Theory of Matter

• The Kinetic Theory, also known as Kinetic Molecular Theory, explains the behavior of particles in gases based on several assumptions:

  1. All matter consists of tiny particles (atoms, molecules, and ions).

  2. Particles are in constant, random motion.

  3. Particles collide with each other and the walls of their container.

  4. Energy lost during collisions is negligible.

Changes of State

• When water molecules collide with ice particles, energy transfers from water to ice, causing the ice's surface particles to vibrate faster and transfer energy to adjacent ice particles.

Plasma State

• Plasma is an energetic state of matter where particles have enough energy to overcome attractive forces both between particles and within atoms.

• In plasma, atoms lose electrons due to intense collisions.

• Most ordinary matter in the universe exists in the plasma state, including stars and interstellar matter.

Thermal Expansion

• As temperature increases, particles move faster and spread apart, leading to thermal expansion, which is the increase in size of a substance due to heating.

• Conversely, substances contract upon cooling.

Solid or Liquid? - Amorphous Solids

• Amorphous solids, such as butter and glass, soften gradually over a temperature range rather than having a specific melting point.

• They lack a crystalline structure.

Solid or Liquid? - Liquid Crystals

• Liquid crystals have a unique state; they start to flow while retaining some ordered geometric structure during the melting process.

• Used widely in LCD technology for devices like phones, TVs, and MP3 players.

Assessments

1. What is the temperature at which vapor pressure equals external pressure?

   • Answer: Boiling Point

2. What is the most common state of matter in the universe?

   • Answer: Plasma

3. What energy amount is needed to change a solid to liquid at its melting point?

   • Answer: Heat of Fusion