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CHEMISTRY
• THE CENTRAL SCIENCE– Explains all aspects of daily life
• A QUALITATIVE SCIENCE– Make and record observations
• A QUANTITATIVE SCIENCE– How much, how many?
CHEMISTRY
• AN EXPERIMENTAL SCIENCE– Observe and test; laboratory requirement
• INTELLECTUAL PURSUIT– Scientific method (observe, hypothesize, test,
theorize, predict, retest and refine, develop law)
• METHOD OF INQUIRY– To probe the world around us and to enable
advances in our quality of life
CHEMISTRY APPLIED TO ALL ASPECTS OF LIFE
• Health care including diagnostics (MRI, CAT, X-rays), medicine (pharmaceuticals) and prevention (cholesterol, heart, osteoporosis)
• Materials for buildings, clothing, roads, consumer products (nylon, kevlar, composites)
• Transportation fuel (ethanol-gas blends)• Agriculture and food (fertilizers, pesticides,
additives, sugar substitutes)• Communication, electronics and computers
CHEMISTRY
• Study of Matter– Matter is characterized by mass and volume– Matter has physical and chemical properties– There are three states of matter: Gas, Liquid,
Solid
• Study of how matter changes• Figure 1.8 shows how matter is classified.
MIXTURE
• A mixture consists of one or more substances present in no fixed proportion.
• Can be separated into substances by physical means; purification.
• Homogeneous mixtures or solutions have uniform properties throughout – Solution of water and sugar, air we breathe
• Heterogeneous mixtures or solutions have nonuniform properties throughout– Oil and vinegar, concrete, colloids (T 1.2)
PURE SUBSTANCE
• In chemistry, a pure substance has characteristic physical and chemical (phys/chem) properties.
• Cannot be broken down by physical means.
• Pure substances are elements or compounds.
ELEMENT
• Fundamental type of matter that cannot be chemically broken down.
• There are 116 known elements with 90 occurring naturally; shown on the Periodic Table
• Building blocks for all substances.• Classified as metals (75%), nonmetals (20%) or
metalloids (5%).• Elements have characteristic phys/chem properties
COMPOUND
• A chemical substance made up of two or more elements in fixed ratio.
• More than 20 million compounds are known.
• Compounds have characteristic phys/chem properties.
• Cannot be resolved into its constituent elements via physical means.
PHYSICAL PROPERTIES
Characteristics of a substance that do not result in a change in the identity of the substance– Examples: color, boiling point, freezing point,
solubility, density, hardness, conductivity, odor
Physical changes (Chapter 2)– Change in form of matter without changing its
chemical identity. E.g. boiling is a change from liquid to vapor
CHEMICAL PROPERTIES
Characteristics of a substance that result in a change in the identity of the substance– Examples: Reactivity; tendency to burn in oxygen,
explode; behave as an acid or base, corrode, decompose
Chemical changes (Chemical Reactions; Chapter 2)– Rearrangement of atoms to give new chemical species