Chemistry

• Chemistry - study of the compositions, structure, and properties of matter and the changes it undergoes.
• The two properties of matter: mass and volume.
• Mass- amount or quantity of matter
• Volume- amount of space occupied
• Atom - Extremely small chemically indivisible particle
• Atom is Greek for "that which cannot be divided"
• Composition- the types and amounts of atoms that make up a sample of matter
• Properties- the characteristics that give each substance a unique identity.
• Properties of matter allow us to distinguish between substances and classify them
• Physical properties - a characteristic that can be observed or measured without changing the identity or composition of the substance
• Example of physical properties: color, odor, taste, size, physical state, boiling point, melting point, density
• EXTENSIVE- depends on the amount of matter
• INTENSIVE- depends on the type of matter, not the amount present
• types of physical properties: extensive and intensive
• Chemical properties - ability or inability of a substance to combine with or change into one or more other substances
• Example of chemical properties: Charcoal burning in air, Iron rust decomposition of food, or Burn, Rot, Rust, Decompose
• Matter can be classified according to its physical state and its composition.
• SOLID - Has a definite shape and volume closely packed
• solids have very rigid, ordered structures, in fixed positions
• Liquids - Has a definite volume, atoms are not widely separated, therefore high density and small compressibility
• liquid - No definite shape i.e. follows the shape of its container
• gases - also known as vapor
• gases - molecules are far apart and move quickly in all directions
• gases - Moving at high speeds, colliding with container, moderate thermal expansion.
• Matter is anything that has mass and takes up space.
• Composition - the types and amounts of atoms that make up a sample of matter.
• Physical change - occurs when a substance alters its state (phase change) but does not change its chemical composition
• Phase change- transition of a substance from one state to another
• Exothermic - heat is given off
• endothermic - absorption of heat
• Melting - solid to liquid
• Freezing - liquid to solid
• Evaporation/Boiling - liquid to gas
• Condensation - gas to liquid
• Sublimation - solid to gas
• Reverse Sublimation - gas to solid
• chemical change - occurs when a substance is converted into a new or different substance
• Energy in physics is the capacity for doing work
• Energy - It may exist in potential, kinetic, thermal. Electrical, chemical.
• Potential energy is stored energy and the energy of position.