121 - Final Exam

Question 1

Define pure substance

Answer 1

A form of matter that always has a definite and constant composition

Question 2

Define element

Answer 2

The simplest type of a substance with unique physical and chemical properties

Question 3

Define molecule

Answer 3

A structure that consists of two or more atoms that are chemically (covalently) bonded together

Question 4

Define compound

Answer 4

A substance composed of two or more elements which are chemically combined

Question 5

How are an atom and molecule different?

Answer 5

Atoms are single units of substance, and molecules are the smallest stable unit.

Question 6

Define chemical formula

Answer 6

Comprised of element symbols and numerical subscripts the type and number of each atom present

Question 7

Define molecular formula

Answer 7

The true or actual number of atoms in the molecule

Question 8

Define empirical formula

Answer 8

The simplest whole number ratio of the atoms

Question 9

Define and give examples of physical properties

Answer 9

Properties that can be observed without changing the substance into another substance (color, density, conductivity, etc.)

Question 10

Define and give examples of chemical properties

Answer 10

Properties that can only be observed by changing the substance into another substance (corrosiveness, flammability, etc)

Question 11

Define intensive properties

Answer 11

Properties that are independent of the amount of substance

Question 12

Define extensive properties

Answer 12

Properties that depend on the amount of substance being observed

Question 13

What is the first law of thermodynamics?

Answer 13

Energy is neither created nor destroyed.

Question 14

Who is the father of modern medicine?

Answer 14

German Paracelsus Theophrastus Bombastus von Hohenheim

Question 15

What is the scientific method?

Answer 15

The process scientists use to explain observations in nature

Question 16

What are the steps of the scientific method?

Answer 16

1. Observation
2. Generalizations / laws
3. Hypotheses / theories
4. Predictions based on theories
5. Experimentation

Question 17

Can theories be proven true?

Answer 17

No, only supported / rejected (contradicted)

Question 18

What is temperature by definition?

Answer 18

A measure of the average kinetic energy of the particles in a sample

Question 19

What is the conversion factor of F to C?

Answer 19

F = 9/5C + 32

Question 20

What is heat?

Answer 20

A measure of the quantity of energy due to molecular motion

Question 21

What is accuracy?

Answer 21

The proximity of a measurement to the “true” value of a quantity

Question 22

What is precision?

Answer 22

The proximity of several measurements to each other

Question 23

What is the law of conservation of mass?

Answer 23

The total mass of substances do not change in chemical reactions.

Question 24

Who is the father of modern chemistry?

Answer 24

Antoine Lavoisier

Question 25

What is the law of definite (or constant) composition?

Answer 25

The elemental composition of a pure substance is always the same. (First proposed by Joseph Proust)

Question 26

What is the law of multiple proportions?

Answer 26

If elements A and B react to form more than one compound, the different masses of A that combined with a fixed mass of element B can be expressed as a ratio of small whole numbers.

Question 27

Who discovered the electron?

Answer 27

J.J. Thompson w/ cathode rays

Question 28

Who discovered the charge of electrons?

Answer 28

Robert Milikan w/ the oil drop experiment

Question 29

What model of the atom did J.J. Thompson propose?

Answer 29

“Plum pudding model” | All electrons are embedded in the jelly-like sphere of positively charged electricity.

Question 30

Who discovered radioactivity?

Answer 30

Henri Becquerel

Question 31

Who named radioactivity?

Answer 31

Marie Curie

Question 32

What is radioactivity?

Answer 32

The spontaneous emission of radiation by an atom.

Question 33

Who discovered the nature of radioactive emissions?

Answer 33

Ernest Rutherford

Question 34

Who discovered the nucleus?

Answer 34

Ernest Rutherford w/ the gold foil experiment

Question 35

Who discovered protons?

Answer 35

Rutherford (he also predicted neutrons)

Question 36

Who confirmed the presence of neutral particles in the nucleus?

Answer 36

James Chadwick

Question 37

Which weighs more, protons or neutrons?

Answer 37

They have about the same mass.

Question 38

Do electrons have mass?

Answer 38

Yes, but it’s so small we ignore it.

Question 39

Who arranged the first periodic table?

Answer 39

Henry Moseley

Question 40

What is an element's atomic number?

Answer 40

The number of protons in the nucleus or the number of electrons in a neutral atom

Question 41

What is an element’s mass number?

Answer 41

The total number of protons and neutrons in an atom’s nucleus

Question 42

Which varies - the amount of protons or neutrons?

Answer 42

Neutrons (elements always have the same number of protons)

Question 43

What are isotopes?

Answer 43

Atoms of the same element that have different number of neutrons and therefore different mass numbers

Question 44

What are hydrates?

Answer 44

Molecules with a specific number of water molecules associated with each formula unit

Question 45

Who is the father of the periodic table?

Answer 45

Mendeleev

Question 46

What is the periodic law of the elements?

Answer 46

When elements are arranged in a particular order (increasing atomic number), elements of similar properties occur at periodic intervals

Question 47

What are columns in a periodic table?

Answer 47

Groups

Question 48

What are rows in a periodic table?

Answer 48

Periods

Question 49

How do ionic bonds form?

Answer 49

Bonds formed by charge structure

Question 50

How do covalent bonds form?

Answer 50

Bonds formed by shared electrons

Question 51

What is the oxidation number for an element?

Answer 51

0

Question 52

What is the oxidation number for a simple monatomic ion?

Answer 52

Equals its charge

Question 53

What should the sum of all neutral molecules be?

Answer 53

0

Question 54

What is H’s oxidation number?

Answer 54

1

Question 55

What is O’x oxidation number?

Answer 55

-2 (except in peroxides where it is -1)

Question 56

What is F’s oxidation number?

Answer 56

-1

Question 57

What are the main points of Dalton’s atomic theory?

Answer 57

1. Each element is composed of extremely small particles called atoms. 2. All atoms of a given element are identical, but the atoms of one element are different from the atoms of all other elements. 3. Atoms of one element cannot be changed into atoms of a different element by chemical reactions, and they are neither created nor destroyed in chemical reactions. 4. Compounds are formed when atoms of more than one element combine, a given compound always has the same relative number and kind of atoms.

Question 58

What is the charge of an electron?

Answer 58

1.602 x 10^-19

Question 59

What are diatomic molecules?

Answer 59

Molecules made up of two atoms

Question 60

What happens in combination reactions?

Answer 60

Two or more substances react to form one product

Question 61

What happens in decomposition reaction?

Answer 61

A single reactant breaks apart to form two or more substances

Question 62

What are combustion reactions?

Answer 62

Rapid reactions that produce a flame, typically involving oxygen

Question 63

What is the formula weight of a compound?

Answer 63

The sum of the atomic weights (AW) of the atoms in the chemical formula of the substance Also called the molecular weight