chapter 1 &2

Question 1

No experiment is a failure because _____

Answer 1

all observations of events in the natural world can be used to revise a hypothesis and to plan tests of a different variable.

Question 2

variable

Answer 2

a factor that changes in an experiment in order to test a hypothesis

Question 3

scientific method

Answer 3

a series of septs followed to solve problems including collecting data, formulating hypothesis, testing the hypothesis, and stating conclusions.

Question 4

Scientific Theory

Answer 4

an explanations of some phenomenon that is based on observation, experimentation, and reasoning.

Question 5

scientific law

Answer 5

a summary of many experimental results and observations; a law tells you how things work

Question 6

Laws and theories are supported by____

Answer 6

experimental results.

Question 7

chemistry

Answer 7

the scientific study of the composition, structure, and properties of matter and the changes that matter undergoes

Question 8

matter

Answer 8

anything that occupies space and has mass.

Question 9

element

Answer 9

a substance that cannon be separated or broken down into simpler substances by chemical means.

Question 10

atom

Answer 10

the smallest unit of an element that maintains the properties of the element.

Question 11

compound

Answer 11

a substance made of atoms of two, or more, different elements that are chemically combined. ex. Nylon is a compound.

Question 12

Molecule

Answer 12

the smallest unit of a substance that keeps all the physical and chemical properties of that substance.

Question 13

compound vs molecule

Answer 13

A molecule is a compound, I think. A compound is made of atoms of two or more different elements, but a molecule may be of the same elements or different elements.
H2O — molecule and a compound, because it’s made of atoms of different elements.
O2 — molecule, not a compound, because it’s made of atoms of the same element.
Compounds are always made of the same elements in the same proportions. I like to think of a substance as simply STUFF.

Question 14

A pure substance

Answer 14

a sample of matter, either a single element or a single compound, that has definite chemical and physical properties. Compounds are subset of substances, therefore.

Question 15

Mixture

Answer 15

a combination of two or more substances that are NOT chemical combined, i.e. pure substances.
mixtures can be homogenous or heterogeneous. Steel is actually a mixture.

Question 16

Atoms can combine to form _____

Answer 16

molecules or compounds.

Question 17

Chemical formulas

Answer 17

representation of the atoms in compounds or molecules.

Question 18

Melting point

Answer 18

the temperature at press at which a solid becomes a liquid.

Question 19

Boiling point

Answer 19

the temperature at which a liquid becomes a gas.

Question 20

Density

Answer 20

D = m/V.

Question 21

Reactivity

Answer 21

(chemical property) the ability of a substance to combine chemically with another substance.

Question 22

Flammability

Answer 22

the ability of a substance to react in the presence of oxygen and burn when exposed to flame.

Question 23

Physical Properties can be observed or measured without changing the composition of matter.

Answer 23

Physical Properties help determine how substances are used.

Question 24

Chemical Properties describe how a substance reacts;

Answer 24

they can be observed when on substance reacts with another.

Question 25

Physical Change affects one or more physical property of a substance without changing its identity, e.g. breaking a piece of chalk in two — it’s still chalk.

Answer 25

Dissolving is a physical change.

Question 26

Compounds can be broken down ONLY through ____

Answer 26

chemical changes

Question 27

Chemical Change

Answer 27

a change that occurs when a substance changes composition by forming one or more new substances.

Question 28

Chemical changes cannot be reversed by _____

Answer 28

physical changes. Chemical changes form new substances that have different properties.

Question 29

_____ changes are often easily reversed.

Answer 29

Physical

Question 30

chemical changes can ONLY be reversed through ________

Answer 30

Chemical Process

Question 31

Melting

Answer 31

from solid to liquid

Question 32

Sublimation

Answer 32

from solid directly to gas

Question 33

freezing

Answer 33

from liquid to solid

Question 34

deposition

Answer 34

from gas directly to solid

Question 35

vaporization

Answer 35

from liquid to gas

Question 36

condensation

Answer 36

from gas to liquid

Question 37

ionization

Answer 37

from gas to plasma

Question 38

deionization

Answer 38

from plasma to gas