Chemistry (Combined)
Principles of Chemistry
States of Matter
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States of Matter
States of Matter
- Matter exists in four states, namely solid, liquid, gas and plasma.
- These different states of matter have distinct properties which can be used to identify them.
Solids
- Solids hold a fixed shape and volume.
- The particles of solids are tightly packed together, causing them to vibrate on the spot.
- Crystalline solids have regular repeating patterns in their particle arrangement. For example, salt and diamond.
- Amorphous solids have irregular particle arrangements. For example, glass and plastic.
Liquids
- Liquids have a definite volume but no definite shape. They take the shape of the container they are in.
- Liquid particles are less closely packed than solids but more so than gases. Their particles slide past each other.
- Viscosity is a property of fluids (liquids and gases) that indicates the resistance to flow. A liquid like honey, which flows slowly, has a high viscosity.
Gases
- Gases have no definite shape or volume.
- The particles of a gas move freely in all directions, which means the gas spreads out and fills any container it is placed in.
- Pressure in gases is caused by gas molecules colliding with the walls of its container.
Changes in States
- Changes in states of matter are caused by varying the temperatures and pressures.
- The names of the state changes are: melting (solid to liquid), freezing (liquid to solid), evaporation (liquid to gas), condensation (gas to liquid), sublimation (solid to gas), and deposition (gas to solid).
The Kinetic Particle Theory
- This theory helps to explain changes in states of matter.
- It considers the movement of particles in solids, liquids and gases - in a solid, the particles have the least kinetic energy, while in a gas, they have the most.
- As one state changes to another (for example, when a solid is heated and turns into a liquid), the average kinetic energy of the particles increases.
