Molecules and Matter

Molecules and Matter Study Guide for GCSE

1. Definitions

   • Matter: Anything that has mass and occupies space.

   • Molecule: A group of two or more atoms that are chemically bonded together.

   • Element: A substance that cannot be broken down into simpler substances by chemical means.

   • Compound: A substance formed when two or more elements are chemically bonded together.

2. States of Matter

   • Solid:

     • Fixed shape and volume.

     • Particles are closely packed together and vibrate in place.

   • Liquid:

     • Fixed volume but takes the shape of the container.

     • Particles are less tightly packed than in solids and can flow past each other.

   • Gas:

     • Neither fixed shape nor fixed volume.

     • Particles are far apart and move freely.

   • Properties of Substances

   • Conductivity: Ability to conduct electricity or heat.

   • Density: Mass per unit volume.

   • Solubility: The ability of a substance to dissolve in a solvent, such as water.

3. Important Concepts

   • Mixtures vs Compounds: Mixtures are made of two or more substances that are not chemically bonded, while compounds are chemically bonded.

   • Solutions: A homogeneous mixture of solute and solvent.