The Particulate Nature of Matter Flashcards
(7 cards)
Kinetic theory of matter
The kinetic theory of matter states that matter is made of tiny particles (i.e. atoms and molecules) and that they are always in constant motion.
Solids
Solids have particles that are packed closely together. The atoms are arranged in a regular pattern due to the strong attractive forces that exists between the particles. These particles therefore cannot move. Instead, they vibrate constantly on the spot.
By giving a solid energy (i.e. heating), the particles will begin to vibrate more vigorously as they gain more energy. Eventually, the particles begin to separate as they start to overcome attractive bonds. Eventually, the particles will have enough separation to move past one another, but still kept relatively close (as attractive forces between particles still exist). The solid has now officially become a liquid.
Liquids
Liquids therefore have particles that are loosely arranged (i.e. can move past one another). They therefore take up the shape of the container in which they’re in. The particles themselves are constantly moving in constant, random motion.
By further heating the liquid, the particles gain even more energy! This will separate the particles even more as they overcome most of the remaining forces of attraction that exists.
Gases
Gases therefore have particles that are very far apart. Again, the particles will be moving in constant, random motion and also take up the shape of its container. Unlike solids and liquids, gases can be compressed.
Bear in mind that if you start to take energy away from a gas (i.e. cooling) then individual particles will have less energy to overcome attractive forces, and will eventually turn back into a liquid. Similarly, by cooling a liquid, it will turn into a solid.
Brownian Motion
Brownian motion is therefore defined as the erratic random movement of microscopic particles in a fluid (i.e. pollen), as a result of continuous bombardment from molecules of the fluid (i.e. water molecules).
Diffusion
Diffusion is the net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient.
The constant random movement of particles (and their kinetic energy) allows diffusion to occur. Ultimately this means that particles will spread out from one place to another.
Factors that affect the rate of diffusion
Concentration gradient, size of the particles that are diffusing, and temperature of the system affect the rate of diffusion. Some materials diffuse readily through the membrane, but others require specialized proteins, such as channels and transporters, to carry them into or out of the cell.
