Ch2

Question 1

Who discovered electrons?

Answer 1

J.J. Thompson in 1897

Discovered through cathode ray experiment.

Question 2

What did R.A. Millikan determine in 1909?

Answer 2

Mass of the electron using the oil drop experiment

Mass of electron: 9.109 × 10−31 kg, Charge: e = −1.602 × 10−19 C.

Question 3

What significant model did Earnest Rutherford propose in 1911?

Answer 3

The nucleus of the atom

Proposed through the gold foil experiment.

Question 4

Describe Thomson’s Plum-Pudding Model.

Answer 4

Electrons are distributed throughout a positively charged sphere.

Question 5

What was the outcome of Rutherford’s Gold Foil Experiment?

Answer 5

Disproved the plum-pudding model, leading to the nuclear atom model.

Question 6

What does the atomic model assume about the nucleus?

Answer 6

Contains nearly all the mass of the atom and is positively charged.

Question 7

What particles make up the nucleus of an atom?

Answer 7

Protons and neutrons.

Question 8

What is the charge and mass of protons?

Answer 8

Charge: +1, Mass: about 1.0 u.

Question 9

What does the atomic number (Z) represent?

Answer 9

The number of protons in an atom.

Question 10

What is the charge and mass of electrons?

Answer 10

Charge: -1, Mass: about 1/2000 of protons.

Question 11

What are neutrons and their role in the nucleus?

Answer 11

Neutral particles that hold protons together.

Question 12

What is the mass number (A)?

Answer 12

The sum of protons and neutrons in an atom’s nucleus.

Question 13

What are isotopes?

Answer 13

Atoms with identical atomic numbers but different mass numbers.

Question 14

What defines the element in a neutral atom?

Answer 14

The number of protons equals the number of electrons.

Question 15

Fill in the blank: The atomic number defines the _______.

Answer 15

element.

Question 16

What is the significance of unified atomic mass units (u)?

Answer 16

Expresses masses of atoms and subatomic particles.

Question 17

What are the categories of elements in the periodic table?

Answer 17

Metals, Nonmetals, Metalloids.

Question 18

What is the arrangement of elements in Mendeleev’s periodic table?

Answer 18

Ordered by increasing atomic mass and similar properties.

Question 19

What defines the modern periodic table?

Answer 19

Elements arranged by increasing atomic number.

Question 20

What are the properties of metals?

Answer 20

Shiny, solid, conductive, malleable, ductile.

Question 21

What is the charge of monoatomic ions in Group 1?

Answer 21

1 plus.

Question 22

What is the charge of monoatomic ions in Group 2?

Answer 22

2 plus.

Question 23

Identify the group and period of aluminum.

Answer 23

Group 13, Period 3.

Question 24

What is the group 16 element with the smallest atomic number?

Answer 24

Oxygen.

Question 25

What is the third-row metalloid?

Answer 25

Silicon.

Question 26

What is the fourth-row alkaline earth element?

Answer 26

Calcium.

Question 27

True or False: The mass number (A) is always greater than or equal to the atomic number (Z).

Answer 27

True.

Question 28

What do the symbols of nuclides represent?

Answer 28

Protons and neutrons in an atom's nucleus.

Question 29

What is the average atomic mass?

Answer 29

The weighted average of masses of all isotopes of an element ## Footnote It takes into account the natural abundance of each isotope.

Question 30

Which element has the lowest atomic number in its group?

Answer 30

Aluminum (Al) in group 13, row 3

Question 31

What is the only metalloid in row 3?

Answer 31

Silicon (Si) in group 14

Question 32

Where are alkaline earth metals located in the periodic table?

Answer 32

Group 2 ## Footnote Includes calcium (Ca) in row 4.

Question 33

How many natural isotopes does Neon have?

Answer 33

Three

Question 34

What is the mass of Neon-20?

Answer 34

19.924 u

Question 35

What is the formula for calculating average atomic mass?

Answer 35

m_Ne = (19.9924 u × 0.904838) + (20.9940 u × 0.002696) + (21.9914 u × 0.092465)

Question 36

What is the molecular mass?

Answer 36

The sum of all average atomic masses of the atoms that are chemically bonded together

Question 37

What is the formula mass used for?

Answer 37

Ionic compounds

Question 38

What is the approximate number of atoms in a copper penny?

Answer 38

27,373,000,000,000,000,000,000

Question 39

What is the mole used for?

Answer 39

To simplify a particle count

Question 40

What is Avogadro's constant?

Answer 40

6.022 × 10^23 particles

Question 41

Fill in the blank: 1 mole is the number of atoms in exactly _______ grams of carbon-12.

Answer 41

12

Question 42

What is molar mass?

Answer 42

The mass (in grams) of one mole of a substance

Question 43

How do you convert milligrams to grams?

Answer 43

Divide by 1000

Question 44

What is the molar mass of calcium carbonate (CaCO3)?

Answer 44

100 g/mol ## Footnote Estimated using whole-number values for Ca, C, and O.

Question 45

What is the number of formula units in a mole of an ionic compound?

Answer 45

Equal to Avogadro's constant (6.022 × 10^23)

Question 46

How many moles are in 502 mg of CaCO3?

Answer 46

0.00502 mol

Question 47

How many carbon atoms are in 4.00 g of butane (C4H10)?

Answer 47

1.66 × 10^23 C atoms

Question 48

Which statement describes elements in a periodic group?

Answer 48

They have similar chemical properties.

Question 49

How many moles of carbon are in 5 moles of ethylene (C2H4)?

Answer 49

10 moles of C

Question 50

What is the value of Avogadro's number?

Answer 50

6.022 × 10^23 ## Footnote Avogadro's number is the number of atoms or molecules in one mole of a substance.

Question 51

What is the relationship between elements in a periodic group?

Answer 51

A) chemical properties. ## Footnote Elements in the same group of the periodic table exhibit similar chemical properties.

Question 52

How many moles of carbon (C) are in 5 moles of ethylene (C2H4)?

Answer 52

10 ## Footnote Ethylene contains 2 moles of carbon per mole of ethylene.

Question 53

Which statement does not describe a physical property of chlorine?

Answer 53

A) Chlorine combines with sodium to form table salt. ## Footnote This statement describes a chemical property, not a physical property.

Question 54

Which element is classified as a semimetal?

Answer 54

B) germanium ## Footnote Semimetals have properties intermediate between metals and nonmetals.

Question 55

What defines isotopes?

Answer 55

An atom that has an atomic number of 34 and a mass number of 76 is an isotope of an atom that has B) an atomic number of 34 and a mass number of 80. ## Footnote Isotopes have the same number of protons but different mass numbers due to varying numbers of neutrons.

Question 56

Which one of the following elements is a poor conductor of heat and electricity?

Answer 56

B) phosphorus ## Footnote Phosphorus is classified as a nonmetal and is known for its poor conductivity.