Kinetic Theory of Matter: States, Properties, and Systems

Kinetic Model of Gases: Microscopic Behavior

For centuries, scientists sought a model to explain the behavior of gases at the microscopic level. The simplest model assumes that a gas consists mainly of empty space occupied by small particles in constant, chaotic motion. This model is called the Corpuscular Kinetic Model.

Key Characteristics of Gases

• When heated, gas temperature increases.
• Gases exert pressure.
• Gases tend to fill the entire volume available.
• A larger volume may result in less pressure (at constant temperature).
• Higher volume and higher temperature are related.
• At higher temperatures, gases diffuse more rapidly.

The Kinetic Theory of Matter

Matter consists of very small particles that cannot be seen. These particles are in continuous, random motion.

Evidence of Particle Motion

• Pollen grains are shaken (Brownian motion).
• Dissolved substances diffuse.
• Solids, liquids, and gases diffuse.
• Dust particles move randomly.

States of Aggregation and Kinetic Theory

Particle Behavior in Different States

• Solids: Particles vibrate in fixed positions.
• Liquids: Particles form groups that constantly change their relative positions.
• Gases: Particles move freely at high speed, widely separated.

Fundamental Properties and Systems of Matter

Matter is present in all bodies that surround us in the universe. It possesses:

• General Properties: Such as volume and mass.
• Characteristic Properties: Used to distinguish one substance from another, such as density, melting temperature, and boiling temperature.

Defining Material Systems

A Material System is a portion of matter isolated for experimental study.

Types of Material Systems

• Heterogeneous System: A system that does not present a uniform appearance at all points.
• Homogeneous System: A system that presents a uniform appearance at all points.

Characteristics of Mixtures and Solutions

Heterogeneous Mixtures

• The proportion of various substances that form a heterogeneous mixture is variable.
• The components of a heterogeneous mixture retain all their individual properties.

Solutions (Homogeneous Mixtures)

• The proportion of the chemical components that make up a solution varies.

Pure Substances: Elements and Compounds

Pure substances have a constant composition and constant characteristic properties.

• Compound: A pure substance consisting of two or more elements combined in fixed proportions. A compound can be decomposed into simpler substances (elements) through chemical processes. Example: Water is a compound as it breaks down into simpler substances via chemical processes.
• Simple Substance (Element): A pure substance that cannot be decomposed into other substances by chemical means. A simple substance is formed by a single type of atom.