The Kinetic Theory of Matter

The Kinetic Theory of Matter

• Matter is anything that has mass and occupies space, composed of tiny particles (atoms, molecules, or ions) in constant motion due to kinetic energy.
• The amount of kinetic energy held in matter is determined by temperature and the state of matter (solid, liquid, or gas).

Diffusion

• Diffusion is the movement of particles from an area of high concentration to an area of low concentration, until the particles are evenly distributed.
• Occurs in both liquids and gases, resulting in a gradient of concentration.

Osmosis

• Osmosis is the movement of water particles from an area of high water concentration to an area of low water concentration, through a semipermeable membrane.
• Occurs in all living cells because water is needed for biological reactions and cell membranes are semi-permeable membranes.

Brownian Motion

• Brownian motion is the constant irregular motion of particles (e.g., pollen grains) floating on water, observed by Robert Brown in 1827.
• Explained by kinetic theory, where air and water particles constantly move and collide with heavier particles, causing them to move irregularly.

States of Matter

• Matter can be divided into three main states: solids, liquids, and gases, with a recently proposed fourth state called plasma (at high temperatures).
• Properties of solids, liquids, and gases are summarized in Table 1.1, showing their differences in volume, shape, and compressibility.

Solid State

• Particles are close together in an orderly fashion, with strong forces of attraction between particles, limiting movement to vibrating around a fixed point.

Liquid State

• Particles are further apart than in a solid, with less orderly arrangement, and weaker forces of attraction between particles, allowing particles to slip slowly over each other.

Gas State

• Particles are very far apart, with random arrangement, and very weak forces of attraction between particles, allowing particles to move freely in all directions at high speeds.

Sublimation

• Sublimation is the process of a solid changing directly into a gas without turning into a liquid first, e.g., dry ice, iodine, and ammonium chloride.

Transitions between States

• Melting: a solid changes into a liquid by gaining heat energy.
• Freezing: a liquid changes into a solid by losing heat energy.
• Boiling or Evaporation: a liquid changes into a gas by gaining heat energy.
• Condensation: a gas changes into a liquid by losing heat energy.
• Sublimation: a solid changes directly into a gas by gaining heat energy.

Heating and Cooling Curves

• Heating curves are obtained by measuring the temperature of a solid at regular intervals as it is heated.
• Cooling curves are obtained by measuring the temperature of a gas as it is cooled.
• Melting point is the temperature at which a solid melts to form a liquid or a liquid freezes to form a solid.
• Boiling point is the temperature at which a liquid boils to form a gas or a gas condenses to form a liquid.