Chapter 1

The Study of Change

Chemistry

the central science studying the composition, structure, properties, and changes of matter

Health and Medicine

• Sanitation systems

• Surgery with anesthesia

• Vaccines and antibiotics

• Gene therapy

Energy and the Environment

• Fossil fuels

• Solar energy

• Nuclear energy

Materials and Technology

• Polymers, ceramics, liquid crystals

• Room-temperature superconductors

Food and Agriculture

• Genetically modified crops

• “Natural” pesticides

• Specialized fertilizers

Macroscopic

Observation of large scale phenomenon

Microscopic

Explanations lie in the microscopic world of atom and molecules

Chemical Reaction

bonds between atoms break and form, resulting in different substances with different properties.

scientific method

a systematic approach to research.

Observation - Representation - Interpretation

hypothesis

a tentative explanation for a set of observations.

Tested -

law

a concise statement of a relationship between phenomena that is always the same under the same conditions

Force = mass x acceleration

theory

a unifying principle that explains a body of facts and/or those laws that are based on them.

Chemistry

the study of matter and the changes it undergoes.

Matter

anything that occupies space and has mass.

substance

a form of matter that has a definite composition and distinct properties.

mixture

a combination of two or more substances in which the substances retain their distinct identities.

Homogenous mixture

composition of the mixture is the same throughout

Heterogeneous mixture

composition is not uniform throughout

Physical means

can be used to separate a mixture into its pure components.

element

a substance that cannot be separated into simpler substances by chemical means.

compound

a substance composed of atoms of two or more elements chemically united in fixed proportions.

• only be separated into their pure components (elements) by chemical means.

physical change

does not alter the composition or identity of a substance.

chemical change

alters the composition or identity of the substance(s) involved.

extensive property of a material

depends upon how much matter is being considered.

• mass

• length

• volume

intensive property of a material

does not depend upon how much matter is being considered.

• density

• temperature

• color

Matter

anything that occupies space and has mass

mass

measure of the quantity of matter

kilogram (kg)

weight

force that gravity exerts on an object weight

= a x mass

Volume

cubic meter (m3)

Density

kg/m3

K to C

K = 0C + 273.15

F to C

0F = 9/5 x 0C + 32

Any digit that is not zero

significant

Zeros between nonzero digits

significant

Zeros to the left of the first nonzero digit

not significant

If a number is greater than 1, then all zeros to the right of the decimal point

significant

If a number is less than 1, then only the zeros that are at the end and in the middle of the number

significant

1.234 - how many figure?

4

606 - how many figure?

3

0.08 - how many figure?

1

2.0 - how many figure?

2

0.00420 - how many figure?

3

478

3

6.01

3

0.825

3

0.043

2

1.310 × 10²²

4

7000

may be four (7.000 × 103), three

(7.00 × 103), two (7.0 × 103), or one (7 × 103).

Accuracy

how close a measurement is to the true value

Precision

how close a set of measurements are to each other

accurate & precise

precise but not accurate

not accurate & not precise