Arrangement and Movement of Molecules
Arrangement and Movement of Molecules
The States of Matter and their Characteristics
- Recognize that all matter is made up of atoms, molecules, and/or ions.
- Understand the characteristics of solids. In a solid, the particles are tightly packed together and vibrate in place, leading to a definite shape and volume.
- Know the characteristics of liquids. Particles in a liquid are less tightly packed and can slide past each other, giving liquids a definite volume but not a definite shape.
- Grasp the characteristics of gases. In a gas, the particles are far apart and move freely, meaning gases have neither a definite shape nor volume.
Particle Motion and Energy
- Understand that particles are always moving, and this motion is determined by their amount of kinetic energy.
- Realize that adding energy, often in the form of heat, to particles will make them move faster, often causing a state change such as melting or boiling.
- Recognize that removing energy slows down particle motion, often leading to a state change like freezing or condensation.
Diffusion and Concentration Gradients
- Understand the concept of diffusion, which involves the movement of particles from an area of high concentration to an area of low concentration.
- Appreciate that diffusion continues until the concentration of particles is equal in all areas (equilibrium is reached).
- Learn that temperature, concentration gradient, particle size, and the presence of a barrier can all affect the rate of diffusion.