Chapter 1: Chemistry: The Study of Change

Question 1

Chemistry

Answer 1

the study of matter and the changes it undergoes

Question 2

scientific method

Answer 2

a systematic approach to research

Question 3

qualitative

Answer 3

data consisting of general observations about the system

Question 4

quantitative

Answer 4

data comprising numbers obtained by various measurements of the system

Question 5

hypothesis

Answer 5

a tentative explanation for a set of observations

Question 6

law

Answer 6

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

Question 7

theory

Answer 7

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

Question 8

matter

Answer 8

anything that occupies space and has mass: water, earth, trees, air, etc

Question 9

substance

Answer 9

a form of matter that has a definite (constant) composition and distinct properties

differ from one another in composition and can be identified by their appearance, smell, taste, and other properties

Question 10

mixture

Answer 10

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

do not have constant composition

can be created and then separated by physical means into pure components without changing the identities of the components

Question 11

homogeneous mixture

Answer 11

the composition of the mixture is the same throughout: spoonful of sugar dissolves in water

Question 12

heterogeneous mixture

Answer 12

the composition of the mixture is not uniform: sand mixed with iron fillings

Question 13

element

Answer 13

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

114 elements identified; 82 naturally occurring, 32 created by scientists

Question 14

compound

Answer 14

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

can only be separated by chemical means into pur componenets

Question 15

physical property

Answer 15

can be measured and observed without changing the composition or identity of a substance: color, melting point, boiling point, etc

Question 16

chemical property

Answer 16

to observe such property, must carry out a chemical change: burning, etc

cannot recover original substance via physical change

Question 17

extensive property

Answer 17

measured value dependent on how much matter is being considered: mass, length, volume, etc

values of same extensive property can be added together

Question 18

mass

Answer 18

the quantity of matter in a given sample of a substance

Question 19

volume

Answer 19

length cubed

Question 20

intensive property

Answer 20

measured value not dependent on how much matter is being considered: density, temperature, etc

values of same intensive property are not additive

Question 21

density

Answer 21

the mass of an object divided by its volume

Question 22

macroscopic properties

Answer 22

properties determined directly with the eye

Question 23

microscopic properties

Answer 23

properties on the atomic or molecular scale that require detection by an indirect method

Question 24

SI

Answer 24

International System of Units

Systeme Internationale d’Unites

Question 25

weight

Answer 25

the force that gravity exerts on an object

Question 26

liter

Answer 26

the volume occupied by one cubic decimeter

Question 27

kelvin

Answer 27

the SI base unit for temperature

absolute temperature scale; lowest temperature attainable is 0K, cannot have negative value

does not have degree sign

Question 28

significant figures

Answer 28

the meaningful digits in a measured or calculated quantity

when used, the last digit is understood to be uncertain

Question 29

accuracy

Answer 29

how close a measurement is to the true value of the quantity that was measured

highly accurate measurements are usually precise too

Question 30

precision

Answer 30

how closely two or more measurements of the same quantity agree with one another

measurements deviate less from averaged measurement

highly precise measurements do not necessarily guarantee accurate results