The Particulate Nature of Matter

Concepts and Theories

Matter is made up of very small particles, which is fundamental to the particle theory of matter.
The properties of these particles (atoms, molecules, or ions) are dependent on the elements they are derived from.
Atoms are the smallest units of an element that can exist on their own or in combination.
These atoms can bond to form molecules, the smallest unit of a compound that can exist independently.
Understanding the properties and interactions of these particles is key to understanding this unit.

The State of Matter

Matter can exist in three states: solid, liquid, and gas. The state of matter is predominantly determined by the motion and arrangement of its particles.
Solids have closely packed particles in a fixed position, thus maintaining a stable, definite shape and volume.
Liquids have more loosely packed particles. They maintain a definite volume but not a definite shape.
Gases have widely spaced particles which move randomly. They can totally fill their container and do not have a set shape or volume.

Changes Between States

Changing from one state to another is achieved through melting, evaporating (including boiling), condensing, or freezing.
Melting point and boiling point are characteristic properties of substances and are dependent on the forces between particles.
Energy changes are associated with changes of state.

Mixture and Pure Substances

Pure substances contain only one type of particle (atoms, molecules, or ions) and have fixed melting and boiling points.
Mixtures contain two or more different types of particles and have variable melting or boiling points.

The Kinetic Particle Theory

The kinetic particle theory is key to understanding the properties and behaviour of matter in different states.
Fundamental concepts include that all matter is composed of particles (atoms, molecules or ions), particles are in perpetual motion, and energy transfer affects the motion of particles.

Brownian Motion

Brownian motion contributes to the understanding of the particulate nature of matter.
It provides evidence of the existence and behaviour of particles. It is observed as the random motion of small particles in a fluid (due to collisions with molecules of the medium).

Diffusion

Diffusion is the process of spreading of particles throughout a given volume until they are uniformly distributed.
Greater temperature and smaller particle size increase the rate of diffusion.

Mass Conservation

The principle of mass conservation states that matter can neither be created nor destroyed, only converted from one form to another (or rearranged).
This principle is especially important in understanding chemical reactions.

Experimental Techniques

Investigating the States of Matter

Experiments often enhance the understanding of the state of matter.
This could include heating or cooling a substance to observe the changes in state.

Measuring Mass

Separating Mixtures

Mixtures can be separated using several techniques including filtration, crystallisation, distillation, and chromatography.
The specific technique employed largely depends on the types of particles present in the mixture.

##Revision and Learning Tools

Flashcards

Writing down theories, concepts, and key definitions on flashcards can be a helpful learning tool.

Study Partner

Explaining complex theories or concepts to someone else can help embed understanding.

Past Paper Questions

Working through relevant past paper questions can help to apply understanding of this unit in an exam context.