Ch 3 Section 3

Question 1

Atoms are much too small to be

Answer 1

Measured individually

Question 2

Chemists can analyze atoms

Answer 2

Quantitatively by knowing fundamental properties of the atoms of each element

Question 3

Mole

Answer 3

A special unit used by chemists to express amounts of particles, such as atoms and molecules

Question 4

All atoms are composed of the

Answer 4

Same basic particles

Question 5

Atoms of different elements have

Answer 5

Different numbers of protons

Question 6

Atoms of the same element all have the same number of

Answer 6

Protons

Question 7

The atomic number (Z) of an element is

Answer 7

The number of protons of each atom of that element

Question 8

All atoms of the element hydrogen have

Answer 8

One proton

Question 9

The atomic number identifies

Answer 9

An element

Question 10

The simplest atoms are those of

Answer 10

Hydrogen

Question 11

Like many naturally occurring elements hydrogen atoms can have

Answer 11

Different numbers of neutrons

Question 12

The most common type of hydrogen is sometimes called

Answer 12

Protium

Question 13

Protium accounts for

Answer 13

99.9885% of the hydrogen atoms found on earth

Question 14

The nucleus of a protium atom consists of

Answer 14

One proton only and it had one electron moving about it

Question 15

Another form of hydrogen is deuterium which accounts for

Answer 15

0.0115% of earths hydrogen atoms

Question 16

Each deuterium atom has a

Answer 16

Nucleus with one proton and one neutron

Question 17

The third form of hydrogen is known as tritium which is

Answer 17

Radioactive

Question 18

Tritium exists in very small

Answer 18

Amounts in nature but can be prepared artificially

Question 19

Each tritium atom has one

Answer 19

Proton, two neutrons, and one electron

Question 20

Isotopes are atoms of the same element that have

Answer 20

Different masses

Question 21

The isotopes of a particular element all have the same number of

Answer 21

Protons and electrons but different numbers of neutrons

Question 22

Most of the elements consist of

Answer 22

Mixtures of isotopes

Question 23

Identifying an isotope requested knowing both the

Answer 23

Name or atomic number of the element and the mass of the isotope

Question 24

The mass number is the

Answer 24

Total number of protons and neutrons that make up the nucleus of an isotope

Question 25

Isotopes are usually identified by

Answer 25

Specifying their mass number

Question 26

There are two methods for

Answer 26

Specifying isotopes

Question 27

In the first method the mass number is written with a

Answer 27

Hyphen after the name of the element (hyphen notation)

Question 28

The second method shows the composition of a

Answer 28

Nucleus using the isotopes nuclear symbol

Question 29

The superscript in nuclear symbol indicates the

Answer 29

Mass number (protons + neutrons)

Question 30

The subscript in nuclear symbol indicates the

Answer 30

Atomic number (number of protons)

Question 31

The number of neutrons is found by

Answer 31

Subtracting the atomic number from the mass number

Question 32

Nuclide is a general term for a

Answer 32

Specific isotope of an element

Question 33

Masses of atoms expressed in grams are

Answer 33

Very small

Question 34

For most chemical calculations it is more convenient to use

Answer 34

Relative atomic masses

Question 35

In order to set up a relative scale of atomic mass one atom has been

Answer 35

Arbitrarily chosen as the standard and assigned a mass value

Question 36

The masses of all other atoms are expressed in

Answer 36

Relation to this defined standard

Question 37

The standard used by scientists to compare units of atomic mass is the

Answer 37

Carbon-12 atom

Question 38

One atomic mass unit or 1 amu

Answer 38

Is exactly 1/12 the mass of a carbon-12 atom

Question 39

The atomic mass of any other atom is determined by comparing it with the mass of the

Answer 39

Carbon-12 atom

Question 40

Isotopes of an element may occur naturally or they may be

Answer 40

Made in the laboratory (artificial isotopes)

Question 41

Although isotopes have different masses they do not

Answer 41

Differ significantly in their chemical behavior

Question 42

The masses of subatomic particles can also be expressed in the

Answer 42

Atomic mass scale

Question 43

The mass of the electron is

Answer 43

0.000 5486 amu

Question 44

The mass of the proton is

Answer 44

1.007 276 amu

Question 45

The mass of a neutron is

Answer 45

1.008 665 amu.

Question 46

The mass number and relative atomic mass of a given nuclide are

Answer 46

Quite close to each other

Question 47

Mass number and relative atomic mass are not identical because the

Answer 47

Proton and neutron masses deviate slightly from 1 amu and the atomic masses include electrons

Question 48

A small amount of mass is changed to energy in the creation of a

Answer 48

Nucleus from its protons and neutrons

Question 49

The percentage of each isotope in the naturally occurring element on earth is

Answer 49

Nearly always the same no matter where the element is found

Question 50

The percentage at which each of an elements isotopes occurs in nature is taken into account when

Answer 50

Calculating the elements average atomic mass

Question 51

Average atomic mass is the

Answer 51

Weighted average of the atomic masses of the naturally occurring isotopes of an element

Question 52

The average atomic mass of an element depends on both the

Answer 52

Mass and the relative abundance of each of the elements isotopes

Question 53

The average atomic mass of copper can be calculated by

Answer 53

Multiplying the atomic mass of each isotope by its relative abundance (in decimal form) and adding the results

Question 54

Most atomic masses are known to

Answer 54

Four or more significant figures

Question 55

The relative atomic mass scale makes it possible to know

Answer 55

How many atoms of an element are present in a sample of the element with a measurable mass

Question 56

Three very important concepts- mole, Avogadro's number, and molar mass- provide

Answer 56

The basis for relating masses in grams to numbers of atoms

Question 57

A mole is the amount of a

Answer 57

Substance that contains as many particles as there are atoms in exactly 12 g of carbon-12

Question 58

The mole is a

Answer 58

Counting unit

Question 59

The number of particles in a mole has been

Answer 59

Experimentally determined in a number of ways

Question 60

The best modern value for the number of particles in a mole is

Answer 60

6.022 141 79 x 10^23 which means that exactly 12 g of carbon contains that number of carbon-12 atoms

Question 61

The number of particles in a mole is known as

Answer 61

Avogadro's number

Question 62

Avogadro's number is named for the 19th century Italian scientist whose ideas were

Answer 62

Crucial in explaining the relationship between mass and numbers of atoms

Question 63

Avogadro's number is the number of

Answer 63

Particles in exactly one mole of a pure substance

Question 64

For most purposes Avogadro's number is rounded to

Answer 64

6.022 x 10^23

Question 65

An alternative definition of mole is the amount of a substance that cot subs

Answer 65

Avogadro's number of particles

Question 66

The molar mass of a substance is the

Answer 66

Mass of one mole of a pure substance

Question 67

Molar mass is usually written in units of

Answer 67

g/ mol

Question 68

The molar mass of an element is numerically equal to the

Answer 68

Atomic mass of the element in atomic mass u to

Question 69

The molar mass of an element contains

Answer 69

One mole of atoms

Question 70

Chemists use molar mass as a

Answer 70

Conversion factor in chemical calculations

Question 71

Avogadro's number can be used to find the

Answer 71

Number of atoms of an element from the amount in moles or to find the amount of an element in miles from the number of atoms

Question 72

Such problems are useful in demonstrating the

Answer 72

Meaning of Avogadro's number

Question 73

In these calculations Avogadro's number is expressed in

Answer 73

Units of atoms per mole

Question 74

Neon is a

Answer 74

Minor component of the atmosphere