CHEM 1102

ASPECTS OF CHEMISTRY

Dr. BILIN PAULA TSAI

Dr. SANGEETA MEREDDY

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