Chemistry Midterm Exam

Front 1

A chemical can be defined as

Back 1

any substance that has a definite composition

Front 2

Biochemistry is the study of

Back 2

the chemistry of living things

Front 3

Which of the following is an extensive property of matter?

Back 3

volume

Front 4

The two most important properties of all matter are

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taking up space and having mass

Front 5

An atom is

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the smallest unit of matter that maintains its chemical identity

Front 6

A compound is

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a substance, made of two or more atoms that are chemically bonded, that can be broken down into simpler, stable substances

Front 7

A measure of the quantity of matter is

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mass

Front 8

A chemical change occurs when

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a leaf changes color in the fall

Front 9

Noble gases are in Group 18, and are best known because they are

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unreactive

Front 10

Under ordinary conditions of temperature and pressure, the particles in a gas are

Back 10

very far from one another

Front 11

The liquid state of matter can be described as

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having a definite volume but not a definite shape

Front 12

A solid substance is

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always the same shape regardless of its container

Front 13

What happens to the energy in a substance when it changes state?

Back 13

It changes from, but is neither destroyed nor increased.

Front 14

The only pure substance listed below is

Back 14

vitamin C (ascorbic acid)

Front 15

A mixture is

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a blend of any two or more kinds of matter, as long as each maintains its own unique properties

Front 16

If a mixture is uniform in composition, it is said to be

Back 16

homogeneous

Front 17

A homogeneous mixture is also called

Back 17

a solution

Front 18

If a mixture is not uniform throughout, it is called

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heterogeneous

Front 19

All known chemical elements are organized into groups based on similar chemical properties in the

Back 19

periodic chart

Front 20

The vertical columns on the periodic table are called

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groups

Front 21

The horizontal rows on the periodic table are called

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periods

Front 22

A nonmetal is usually

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brittle

Front 23

Metalloids are often

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semiconductors

Front 24

Nitrogen monoxide and oxygen, both colorless gases, form a red-brown gas when mixed. Nitrogen monoxide and oxygen are called

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reactants

Front 25

A physical change occurs when a

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glue gun melts a glue stick

Front 26

What is 1.245 633 501 x 10^8 rounded to four significant figures?

Back 26

1.246 x 10^8

Front 27

Using a metric ruler with 1 mm divisions, the sides of a rectangular piece of plywood were measured as 3.54 cm and 4.85 cm, which corresponds to an area of 17.1690 cm^2. Which of these shows the area expressed correctly?

Back 27

17.2 cm^2

Front 28

These values were recorded as the mass of products when a chemical reaction was carried out three separate times: 8.83 g; 8.84 g; 8.82 g. The mass of products from that reaction is

Back 28

precise, but not accurate

Front 29

Which of the following does not describe a direct proportionality between x and y?

Back 29

xy=k

Front 30

If repeated measurements agree closely but differ widely from the accepted value, these measurements are

Back 30

precise, but not accurate

Front 31

The standard base unit for mass is the

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kilogram

Front 32

A change in the force of gravity on an object will affect its

Back 32

weight

Front 33

When 1.92 x 10^-6 kg is divided by 6.8 x 10^2 ml, the quotient equals

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2.8 x 10^-9 kg/mL

Front 34

The graphs of two variables that are inversely proportional to one another is

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a hyperbola

Front 35

The result of dividing 10^7 by 10^-3 is

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10^10

Front 36

Standards of measurement are chosen because they

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are reproducible in another laboratory

Front 37

Which of these measurements has only nonsignificant zeros?

Back 37

0.0037 mL

Front 38

Which of these is a measure of the amound of material?

Back 38

mass

Front 39

How would 0.00930 m be expressed in scientific notation?

Back 39

9.30 x 10^-3 m

Front 40

A measurement that closely agrees with an accepted value is best described as

Back 40

accurate

Front 41

The quantity of matter per unit volume is

Back 41

density

Front 42

The relationship between the mass m of a material, its volume V, and its density D is

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D=m/V

Front 43

A statement that can be tested experimentally is a

Back 43

hypothesis

Front 44

If values for x and y vary as an inverse proportion

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their product is a constant

Front 45

What is the density of 37.72 g of material whose volume is 6.80 cm^3?

Back 45

5.55 g/cm^3

Front 46

Two variables are directly proportional if their what has a constant value

Back 46

quotient

Front 47

When adding numbers, the sum should be rounded so that the final digit is in the same place as the

Back 47

leftmost digit of the numbers added

Front 48

The graph of two variables that are directly proportional to one another is

Back 48

a straight line

Front 49

The number of significant figures in the measurement 2010 cm is

Back 49

3

Front 50

Three samples of 1.12 g, 1.8 g, and 1.562 g are mixed together. The combined mass of the three samples, expressed to the correct number of significant figures, would be recorded as

Back 50

4.5 g

Front 51

A numerical result is said to have good precision if

Back 51

repeated measurements agree closely

Front 52

All of the following are steps in the scientific method except

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discarding data inconsistent with the hypothesis

Front 53

The symbols for units of length in order from largest to smallest are

Back 53

km, m, cm, mm

Front 54

The measurement 0.035550 g rounded off to two significant figures would be

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0.036 g

Front 55

Which of the following observations is quantitative?

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The liquid boils at 100 degrees Celsius

Front 56

100 mL is equivalent to

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1 deciliter

Front 57

A chemist obtained the values 5.2246 g, 5.2353 g, and 5.2501 g for the mass of a sample. Without knowing the true mass of the sample, it can be said that these values have

Back 57

poor precision

Front 58

Two variables are inversely proportional if their what has a constant value

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product

Front 59

Which of these is not an SI base unit?

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liter

Front 60

Which of these measurements has been expressed to three significant figures?

Back 60

0.202 g

Front 61

Dalton incorporated the law of conservation of mass into his atomic theory by asserting that

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atoms are indivisible

Front 62

If each atom of element D has 3 mass units and each atom of element E has 5 mass units, a molecule composed of one atom each of D and E has

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8 mass units

Front 63

If 4.0 g of element A combine with 10. g of element B, then 12 g of element A combine with how many grams of element B?

Back 63

30

Front 64

In oxides of nitrogen, such as N2O, NO, NO2, and N2O3, atoms combine in small whole-number ratios. This evidence supports the law of

Back 64

multiple proportions

Front 65

If 63.5 g of copper combine with 16 g of oxygen to form the compound CuO, how many grams of oxygen will be needed to combine with the same amount of copper to form the compound CuO2?

Back 65

32

Front 66

According to the law of definite proportions, any two samples of KCl have

Back 66

the same ratio of elements

Front 67

According to the law of conservation of mass, when sodium, hydrogen, and oxygen react to form as compound, the mass of the compound is what the sum of the masses of the individual elemtns.

Back 67

equal to

Front 68

The principles of atomic theory recognized today were conceived by

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Dalton

Front 69

According to Dalton's atomic theory, atoms

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of each element are identical in size, mass, and other properties

Front 70

Which of the following is not part of Dalton's atomic theory?

Back 70

The number of protons in an atom is its atomic number

Front 71

Dalton's atomic theory agrees with modern atomic theory except for the statement that

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atoms are not divided in chemical reactions

Front 72

Which of the following statements is true according to modern atomic theory?

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Atoms of the same element may have different masses

Front 73

Which concept in Dalton's atomic theory has been modified?

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Atoms cannot be divided

Front 74

The atomic theory proposed by Dalton has been

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expanded and modified

Front 75

In early experiments on electricity and matter, an electrical current was passed through a glass tube containing

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gas under low pressure

Front 76

When an electrical current passed through a glass tube, it caused the surface of the tube directly across from the cathode to glow. Scientists concluded that

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the particles of the beam were negatively charged

Front 77

Experiments with cathode rays led to the discovery of the

Back 77

electron

Front 78

After measuring the ratio of the charge of a cathode ray particle to its mass, Thomson concluded that the particles

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had a very small mass

Front 79

Because any element used in the cathode produced electrons, scientists concluded that

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all atoms contained electrons

Front 80

The deflection of cathode rays in Thomson's experiments was evidence of the what nature of electrons

Back 80

charged

Front 81

Whose series of experiments identified the nucleus of the atom?

Back 81

Rutherford

Front 82

In Rutherford's experiments, most of the particles

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passed through the foil

Front 83

Because most particles fired at metal foil passed straight through, Rutherford concluded that

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atoms were mostly empty space

Front 84

Because a few alpha particles bounced back from the foil, Rutherford concluded that they were

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repelled by densely packed regions of positive charge

Front 85

Rutherford's experiments led him to conclude that atoms contain massive central regions that have

Back 85

a positive charge

Front 86

A positively charged particle with mass 1.673 x 10-24 g is an

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proton

Front 87

A nuclear particle that has about the same mass as a proton, but no electrical charge is an

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neutron

Front 88

The nucleus of an atom has all the following characteristics except that it

Back 88

contains nearly all of the atom's volume

Front 89

Which part of an atom has a mass of approximately equal to 1/2000 of the mass of a common hydrogen atom?

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electron

Front 90

An atom is electrically neutral because

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the numbers of protons and electrons are equal

Front 91

Nuclear forces exists because the particles in the nucleus are

Back 91

close together

Front 92

Most of the volume of an atom is occupied by the

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electrons

Front 93

The charge due to the electrons of a neutral atom

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balances the charge on the nucleus

Front 94

The smallest unit of an element that can exist either alone or in combination with other such particles of the same of different elements is the

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atom

Front 95

The radius of an atom extends to the outer edge of the

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region occupied by the electrons

Front 96

Isotopes are atoms of the same element that have different

Back 96

masses

Front 97

The most common form of hydrogen has

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no neutrons

Front 98

The tritium atom consists of

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one proton, two neutrons, and one electron

Front 99

How many isotopes of hydrogen are known?

Back 99

3

Front 100

All isotopes of hydrogen contains

Back 100

one proton

Front 101

The total number of protons and neutrons in the nucleus of an atom is its

Back 101

mass number

Front 102

As the mass number of an element's isotopes of an element increases, the number of protons

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remains the same

Front 103

As the atomic number increases, the number of electrons in a neutral atom

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increases

Front 104

All atoms of the same element have the same

Back 104

atomic number

Front 105

In determining the atomic mass of elements, the standard is teh

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C-12 atom

Front 106

The relative atomic mass of an atom can be found by comparing the mass of the atom to the mass of

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one atom of carbon-12

Front 107

The carbon-12 atom is assigned a relative mass of exactly

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12 amus

Front 108

The average atomic mass of an element is the average of the atomic masses of its

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naturally occurring isotopes

Front 109

The atomic mass of an element listed in the periodic table is the

Back 109

average atomic mass

Front 110

An aluminum isotope consists of 13 protons, 13 electrons, and 14 neutrons. Its mass number is

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27

Front 111

Neon-22 contains 12 neutrons. It also contains

Back 111

10 protons

Front 112

The number of atoms in 1 mol of carbon is

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6.022 x 1023

Front 113

The number of atoms in a mole of any pure substance is called

Back 113

Avogadro's constant

Front 114

The atomic number of neon is 10. The atomic number of calcium is 20. Compared with a mole of neon, one mole of calcium contains

Back 114

an equal number of atoms

Front 115

To determine the molar mass of an element, one must know the element's

Back 115

average atomic mass

Front 116

Avogadro's number is

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the number of particles in 1 mole of a pure substance

Front 117

Molar mass

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Both a and b

Front 118

The mass of 2.0 mol of oxygen atoms (atomic mass 16.00 amu) is

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32 g

Front 119

The mass of a sample containing 3.5 mol of silicon atoms (atomic mass 28.0855 amu) is approximately

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98 g

Front 120

Visible light, X rays, infrared radiation, and radio waves all have the same

Back 120

speed

Front 121

The main energy level that can hold only two electrons is the

Back 121

first

Front 122

A three-dimensional region around a nucleus where an electron may be found is called a(n)

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orbital

Front 123

The region outside the nucleus where an electron can most probably be found is the

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electron cloud

Front 124

If electromagnetic radiation A has a lower frequency than electromagnetic radiation B, then compared to B, the wavelength of A is

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longer

Front 125

The electron notation for aluminum (atomic number 13) is

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1s2 2s2 2p6 3s2 3p1

Front 126

The change of an atom from an excited state to the ground state always requires

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emission of electromagnetic radiation

Front 127

The Bohr model of the atom was an attempt to explain hydrogen's

Back 127

line-emission spectrum

Front 128

An orbital that can never exist according to the quantum description of the atom is

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3f

Front 129

The Pauli exclusion principle states that no two electrons in the same atom can

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have the same set of quantum numbers

Front 130

Which model of the atom explains the orbital of electrons as waves?

Back 130

the quantum model

Front 131

If the third main energy level contains 15 electrons, how many more could i possible hold?

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3

Front 132

The energy of a photon is related to its

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frequency

Front 133

The main energy levels of an atom are indicated by the

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principal quantum numbers

Front 134

The number of possible different orbital shapes for the third energy level is

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3

Front 135

The distance between two successive peaks on adjacent waves is its

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wavelenth

Front 136

If the s and p sublevels of the highest main energy level of an atom are filled, how many electrons are in their main energy level?

Back 136

8

Front 137

The angular momentum quantum number indicates the

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shape of an orbital

Front 138

A spherical electron cloud surrounding an atomic nucleus would best represent

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an s orbital

Front 139

The emission of electrons from metals that have absorbed photons is called the

Back 139

photoelectric effect

Front 140

If electrons in an atom have the lowest possible energies, the atom is in the

Back 140

ground state

Front 141

The wave model of light does not explain

Back 141

the photoelectric effect

Front 142

A single orbital in the 3d level can hold how many electrons?

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2

Front 143

Bohr's theory helped explain why

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excited hydrogen gas gives off certain colors of light

Front 144

According the Bohr, electrons cannot reside at what in the figure below?

Back 144

point C

Front 145

The specific wavelengths of light seen through a prism that are made when high voltage current is passed through a tube of hydrogen gas at low pressure is a

Back 145

continuous electromagnetic spectrum

Front 146

How many orbitals can exist at the third main energy level?

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9

Front 147

A line spectrum is produced when an electron moves from one energy level

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to a lower energy level

Front 148

The electron in a hydrogen atom has its lowest total energy when the electron is in its ground state

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ground state

Front 149

The spin quantum number indicates that the number of possible spin states for an electron in an orbital is

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2

Front 150

The quantum number that indicates the position of an orbital about the three axes in space is the

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magnetic quantum number

Front 151

The frequency of electromagnetic radiation is measured in waves/second, or

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hertz

Front 152

The sequence in which energy sublevels are filled is specified by

Back 152

the Aufbau principle

Front 153

The major difference between a 1s orbital and a 2s orbital is that

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the 2s orbital is at a higher energy level

Front 154

The equation E=hv helped Louis de Broglie determine

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whether electrons behave as particles

Front 155

Which is not part of hydrogen's line-emission spectrum?

Back 155

Aufbau series

Front 156

For the f sublevel, the number of orbitals is

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7

Front 157

Both the Heisenberg uncertainty principle and the Schrodinger wave equation

Back 157

led to the concept of atomic orbitals

Front 158

The number of orbitals for the d sublevel is

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5

Front 159

According to the quantum theory of an atom, in an orbital

Back 159

an electron's position cannot be known preciselyT

Front 160

the p orbitals are shaped like

Back 160

dumbbells

Front 161

Two electrons in the 1s orbital must have different spin quantum numbers to satisfy

Back 161

the Pauli exclusion principle

Front 162

Because c, the speed of electromagnetic radiation, is a constant, the wavelength of the radiation is

Back 162

inversely proportional to its frequency

Front 163

Max Planck proposed that a hot object radiated energy in small, specific amounts called

Back 163

quanta

Front 164

How many quantum numbers are needed to describe the energy state of an electron in an atom?

Back 164

4

Front 165

Which model of the atom explains why excited hydrogen gas gives off certain colors of light?

Back 165

the Bohr model

Front 166

Which energy level change shown in the diagram below emits the highest energy?

Back 166

an electron moving from E2 to E1

Front 167

The letter designations for the first four sublevels with the maximum number of electrons that can be accommodated in each sublevel are

Back 167

s:2, p:6: d:10, f:14

Front 168

According to the Bohr model of the atom, the single electron of a hydrogen atom circles the nucleus

Back 168

in specific, allowed orbits

Front 169

A quantum of electromagnetic energy is called an

Back 169

photon

Front 170

The atomic sublevel with the next highest energy after 4p is

Back 170

5s

Front 171

The spin quantum number of an electron can be thought of as describing

Back 171

the direction of electron spin

Front 172

All of the following describe the Heisenberg uncertainly principle except

Back 172

it helps to locate an electron in an atom

Front 173

Because excited hydrogen atoms always produce the same line-emission spectrum, scientists concluded that hydrogen

Back 173

released photons of only certain energies

Front 174

Both copper(atomic number 29) and chromium (atomic number 24) appear to break the pattern in the order of rilling the 3d and 4s orbitals. This change in pattern is expressed by

Back 174

a reduction in the number of electrons in the 4s orbital and an increase in the 3d orbital

Front 175

For an electron in an atom to change from the ground state to an excited state

Back 175

energy must be aborbed

Front 176

"Orbitals of equal energy are each occupied by one electron before any is occupied by a second electron, and all electron in singly occupied orbitals must have the same spin" is a statement of

Back 176

Hund's rule

Front 177

How many electrons can occupy the s orbitals at each energy level?

Back 177

two, if they have opposite spins

Front 178

How many electrons are needed to completely fill the fourth energy level?

Back 178

32

Front 179

Which of the following lists atomic orbitals in the correct order they are filled according to the Aufbau principle?

Back 179

1s2s2p3s3p4s3d4p5s