lecture 1

Question 1

How do scientists know that it is extraterrestrial glycine and not contamination from Earth?

Answer 1

They measured the atomic isotopes contained in the sample.

Question 2

Law of Conservation of Mass

Answer 2

the total mass remains constant during a chemical reaction

Question 3

A _______is a tentative explanation of some regularity of nature

Answer 3

hypothesis

Question 4

If a hypothesis successfully passes many tests, it becomes known as a

Answer 4

thoery

Question 5

a theory is

Answer 5

a tested explanation of basic natural phenomena.

Question 6

two principal ways of classifying matter: are

Answer 6

its physical state and chemical constitution

Question 7

physical states are

Answer 7

Solid
Liquid
Gas

Question 8

chemical constitution is

Answer 8

Element
Compound
Mixture

Question 9

solid form of matter characterized by rigidity; a solid is relatively _________ and has a fixed _____&______

Answer 9

incompressible,shape and volume.

Question 10

liquid matter that is a relatively ________ fluid; liquid has a fixed_____ but no fixed _____

Answer 10

incompressible, volume, shape.

Question 11

Gas matter that is an easily _____ fluid; a given quantity of gas will fit into a ______

Answer 11

compressible, container of almost any size or shape.

Question 12

Intensive Properties

Answer 12

Are independent of the amount of the substance that is present.
Density, boiling point, color, etc.

Question 13

Extensive Properties

Answer 13

Depend upon the amount of the substance present.

Mass, volume, energy, etc.

Question 14

Physical Changes

in matter that do not change the______ of a substance. examples

Answer 14

composition ,state, temperature, volume

Question 15

Chemical changes result in _______ _____ and are usually ________ , examples

Answer 15

new substances, irreversible Combustion, oxidation, decomposition,

Question 16

A physical property is a

Answer 16

characteristic that can be observed for a material without changing its chemical identity.

Question 17

examples of physical property

Answer 17

are physical state (solid, liquid,or gas), melting point, color, etc.

Question 18

A chemical property is

Answer 18

characteristic of a material involving its chemical change.

Question 19

examples of chemical property

Answer 19

corrosiveness).

Flammability,reactivity with acid,

Question 20

An element is

Answer 20

a substance that cannot be decomposed by any chemical reaction into simpler substances.

Question 21

The smallest unit of an element

Answer 21

is the atom.

Question 22

A compound is a

Answer 22

substance composed of two or more elements chemically combined.

Question 23

The smallest unit of a compound is the

Answer 23

molecule.

Question 24

law of definite proportions states

Answer 24

that a pure compound, whatever its source, always contains definite or constant proportions of the elements by mass.

Question 25

A mixture is a material that

Answer 25

can be separated by physical means into two or more substances.

Question 26

Unlike a pure compound, a mixture has _____ ______

Answer 26

variable composition.

Question 27

Mixtures are classified as:

2 way

Answer 27

heterogeneous, homogeneous

Question 28

heterogeneous mixtures consist of

Answer 28

physically distinct parts (such as a mixture of sugar and salt crystals)

Question 29

homogeneous mixtures are

Answer 29

when the properties are uniform throughout (such as sodium chloride dissolved in water)

Question 30

Homogenous mixtures are often called

Answer 30

solutions