chemistry unit 3

• Qualitative information is non numerical information (descriptions).
• Quantitative information is numerical data.
• An observation is qualitative information gathered through the senses.
• An interpretation is an attempt to put meaning to an observation.
• a description is a list of the properties of something
• date is quantitative information experimentally determined or obtained from references
• an experiment is a test or procedure thats carried out to discover a result
• a hypothesis is a single, unproven assumption or idea which attempts to explain why nature behaves in a specific way
• a theory is a set of hypotheses that tie together a large number of observations into a logical pattern
• a law is a broad generalization or summary statement which describes a large amount of experimental evidence stating how nature behaves when a particular situation occurs
• Hypotheses are normal single assumptions and narrow in scope
• matter is defined as anything that has mass and volume
• substances are things that have a unique and identifiable set of properties
• physical property of a substance is a property that can be found without creating a new substance
• chemical property is the ability of a substance to undergo chemical reactions and change into new substances
• intensive property is a physical property that doesn't depend on how much of the substance is present
• extensive property is a physical property that depends on how much of the substance is present
• solids are rigid and don't readily change shape. under heat or pressure, solids only have small changes in volume
• liquids have fixed volume and take shape of the container
• gases don't have fixed shapes or volume.
• element is a substance which cannot be separated into simpler substances
• atom is the smallest unit of the element that has the properties of the element
• molecule is a group of atoms joined together by chemical bonds
• ion is an atom/molecule with electric charge
• particle is a general term for describing atoms, molecules or ions
• a homogeneous substance has only one phase
• a heterogeneous substance has multiple phases
• a pure substance has unchanging compositions, all particle are the same
• a mixture is made up of two or more substances with variable compositions
• a mechanical mixture is a heterogeneous mixture with clear different parts
• a solution is a homogeneous mixture. Solutions in water have the symbol aq
• compounds are substances composed of two or more types of atoms bonded together
• Hand separation- used for solids in liquid or solid in solid when solid is large enough or has magnetic properties to be removed from mixture
• Filteration- solids in large amounts of liquids, liquid drawn through filter paper leaving solid behind
• Evaporation- Solids in liquid, heat is applied to heat liquid above boiling point. Liquid evaporates leaving solid behind. Used when liquid is not need
• Distillation- solid in liquid or liquid in liquid, is separated by boiling liquids, all liquid is collected
• Crystallisation- solid in liquid, heating until it dissolves then cooling so that crystals form
• Chromatography- solid in gas, gas passes over stationary phase (paper) with spots appearing on paper where substance was present
• Chromatography- mixtures with different colours can be seperated using chromotography