States of Matter: Properties, Kinetic Theory, and Elements
States of Matter: Properties and Characteristics
Solids
Solids have a definite mass, shape, and volume. They are generally difficult to compress, and their density is close to that of liquids. Key properties include elasticity, fragility, and hardness.
Liquids
Liquids have a definite mass and volume but take the shape of their container. They are difficult to compress and expand when heated. Important properties include surface tension, capillarity, and viscosity.
Gases
Gases have a definite mass but no definite shape or volume, occupying the entire container. They expand when heated and spread easily, mixing spontaneously with other gases without agitation.
Plasma
Plasma is the most abundant state of matter in the universe. It behaves like a fluid and gas, exhibiting low viscosity. Liquids, however, can slide and escape through ducts or small holes.
Kinetic Molecular Theory
The kinetic molecular theory describes matter as being composed of discontinuous particles in constant motion.
- Particles are extremely small and in continuous motion.
- Forces of attraction exist between particles, varying by substance.
Solids (Kinetic Molecular Theory)
Particles vibrate but do not move from place to place, preventing flow. Particles are in contact and cannot be compressed.
Liquids (Kinetic Molecular Theory)
Particles move continuously, allowing liquids to flow. Intermolecular forces are intermediate between gases and solids. Particles are in contact and cannot be compressed further.
Gases (Kinetic Molecular Theory)
Particles move in all directions, colliding with each other and the container walls. Intermolecular forces are practically nonexistent.
Changes of State
- Liquid to Solid: Freezing; Solid to Liquid: Melting (Fusion)
- Gas to Liquid: Liquefaction or Condensation; Liquid to Gas: Vaporization
- Gas to Solid: Sublimation (occurs at a constant temperature for pure substances)
General Properties of Matter
- Magnetism: Ability to be attracted by a magnet.
- Hardness: Resistance of a substance to being scratched.
- Tenacity: Resistance of solids to being broken.
- Conductivity: Ability to conduct electricity and heat.
- Solubility: Amount of a substance that dissolves in a solvent at a given temperature.
- Viscosity: Resistance of a substance to flow.
- Malleability: Ability to be transformed into thin layers without breaking.
- Fragility: Ease with which a substance breaks when force is applied.
- Density: Relationship between mass and volume.
- Odor and Color: Impressions produced on the senses of smell and sight.
Iron and pure substances have identifiable characteristics and properties.
Elements and Compounds
The universe is a heterogeneous mixture of pure substances.
Reactions
A pure substance can be broken down into simpler pure substances (decomposition). Electrolysis of water yields two pure substances. Elements cannot be decomposed further.
Compounds are formed from elements in fixed proportions. They are not simply mixtures of elements.
Elements are pure substances that cannot be broken down into other simple substances.
Abundance of Elements
Living organisms are composed of approximately 99% of six known elements (carbon, oxygen, nitrogen, hydrogen, calcium, and phosphorus). The Earth’s interior is primarily iron, while the crust is composed of oxygen and silicon. The universe is approximately 90% hydrogen and 9% helium.
Atoms and Molecules
An element is composed of atoms, and a compound is composed of molecules.
Matter is composed of units such as atoms and molecules.