Chm 151 exam 1

Question 1

Physical Change

Answer 1

-identity is maintained
- can change appearance, size, shape
- make up is the same

Question 2

Chemical Change

Answer 2

• Make up has changed
  -one or more substances (reactants) transform into other substances (products)
• what we start with we don’t end with

Question 3

Extensive Properties

Answer 3

-value depends on “how much is there”
-quantity of matter”
- DOES NOT identify type of matter, just says how much there is

Question 4

Intensive properties

Answer 4

-value DOES NOT depend on quantity
-Often used to identify type of matter

Question 5

Heterogenous

Answer 5

• a physical combination of substances that is not uniform throughout
• when different samples are taken from the same mixture it may result in different compositions

Question 6

Homogenous

Answer 6

• a physical combination of substances that are uniform
• when different samples are taken, both will have identical compositions

Question 7

2 substances present
2 phases

Answer 7

Heterogenous

Question 8

2 substances
1 phase

Answer 8

Homogenous

Question 9

Elements

Answer 9

a substance that cannot be broken down into simpler substances by chemical means
- has distinct physical + chemical properties

Question 10

Compound

Answer 10

• a chemical combination of elements that has a definite composition and its own set of properties

Question 11

Pure Substances

Answer 11

-a substance in which all of the particles that make up that substance are exactly the same kind

Question 12

What are pure substances?
1. elements
2. compounds
3. mixtures

Answer 12

Elements + compounds are pure substances

Question 13

Mixture

Answer 13

• a physical combination of substances that has a nondefinite composition
  -its properties are characteristics of its compounds

Question 14

density

Answer 14

How much mass something has relative to its volume

Question 15

Empirical Formula

Answer 15

Chemical formula of a compound that used the SMALLEST whole number ratio of atoms

Question 16

Molecular Formula

Answer 16

• the actual whole number of atoms of each element in one molecules of a covalent compound

Question 17

How are isotopes of an element related to each other?

Answer 17

• if 2 atoms have the same number of protons but different number of neutrons –> they are isotopes of each other
• isotopes are still elements of the same element because they have the same atomic number, but they have different masses because of different number of neutrons.

Question 18

Isotopic Abundance

Answer 18

the relative proportion of each different isotope of an element that exists naturally
-usually expressed as a percentage
- tells us how much of each type of isotope is found in a sample

Question 19

Ionic Bond

Answer 19

• occurs when one atom completely transfer electrons to another atom, creating oppositely charger ions that attract each other

Question 20

Which bonds “donate” electrons

Answer 20

Ionic Bonds

Question 21

Which bond “shares” electrons

Answer 21

Covalent/Molecular Bond

Question 22

Covalent Bond

Answer 22

• forms when atoms SHARE electrons to acheive stability

Question 23

Metal + non-metal

Answer 23

IONIC

Question 24

Nonmetal + Nonmetal

Answer 24

Covalent/ Molecular

Question 25

Examples of extensive properties

Answer 25

• mass, length, volume

Question 26

Examples of intensive properties

Answer 26

-color, melting/boiling point, solubility, density

Question 27

J.J. Thompson

Answer 27

cathode ray experiments, discovered electron: has negative charge, charge to mass ratio, has v. light mass

Question 28

Robert Millikan

Answer 28

oil drop experiments, calculated actual charge on electron and its mass (using Thompson’s charge to mass ratio)