1.2 THE NUCLEAR ATOM

Question 1

What is the mass and charge of a proton?

Answer 1

A proton has a relative mass of 1 and a charge of +1.

Question 2

What is the relative mass and charge of an electron?

Answer 2

An electron has a negligible mass and a charge of -1.

Question 3

Which subatomic particles are in the nucleus of an atom?

Answer 3

The subatomic particles in the nucleus of an atom are protons and neutrons.

Question 4

True or False?

Atoms are made of subatomic particles.

Answer 4

True.

Atoms are made of subatomic particles including protons, neutrons, and electrons.

Question 5

True or False?

Electrons have a larger mass than protons.

Answer 5

False.

Electrons have a much smaller mass than protons.

Question 6

Which sub-atomic particle is not found inside the nucleus?

Answer 6

The sub-atomic particle that is not found inside the nucleus is the electron.

Question 7

What is the relative mass and charge of a neutron?

Answer 7

An neutron has a relative mass of 1 and charge of 0.

Question 8

True or False?

The nucleus of an atom has no charge overall.

Answer 8

False.

The nucleus of an atom has a positive charge due to the presence of positive protons and neutral neutrons.

Question 9

The subatomic particles in the nucleus are known as______________ ‎ .

Answer 9

The subatomic particles in the nucleus are known as ‎ nucleons.

Question 10

The mass of an atom is concentrated in the ‎_____________ .

Answer 10

The mass of an atom is concentrated in the ‎ nucleus.

Question 11

Define atomic number.

Answer 11

Atomic number is the number of protons.

Question 12

Define mass number.

Answer 12

Mass number is the number of protons and neutrons.

Question 13

How do you calculate the number of neutrons in an atom?

Answer 13

To calculate the number of neutrons in an atom:

Number of neutrons = mass number - atomic number

OR

Number of neutrons = mass number - number of protons

Question 14

How do you determine the number of electrons in an atom?

Answer 14

The number of electrons in an atom is the same as the number of protons / the atomic number.

Question 15

Calculate the number of protons, neutrons and electrons in an atom of 2713Al

Answer 15

The number of protons, neutrons and electrons in an atom of 2713Al :

Protons = 13

Neutrons = 27 - 13 = 14

Electrons = 13

Question 16

True or False?

Atoms and ions of the same element have the same number of protons.

Answer 16

True.

Atoms and ions of the same element have the same number of protons.

Question 17

True or False?

The symbol used to represent atomic mass is M.

Answer 17

False.

The symbol used to represent atomic mass is A.

Question 18

Why are atoms electrically neutral?

Answer 18

Atoms are electronically neutral because they have the same number of protons and electrons so the positive and negative charges cancel each other out.

Question 19

Calculate the number of protons, neutrons and electrons in a magnesium ion, Mg2+.

Answer 19

The number of protons, neutrons and electrons in a magnesium ion, Mg2+ is:

Protons = 12

Neutrons= 12

Electrons = 10

Question 20

The symbol used to represent atomic number is ______________ ‎.

Answer 20

The symbol used to represent atomic number is Z.

Question 21

Identify the number of protons, neutrons and electrons in a oxide ion, O2-.

Answer 21

The number of protons, neutrons and electrons in a chloride ion, O2- is:

Protons = 8

Neutrons = 8

Electrons = 10

Question 22

What is an isotope?

Answer 22

An isotope is an atom of the same element containing the same number of protons but different numbers of neutrons.

Question 23

Which of the following are isotopes?
13 6C
14 6C
14 7N

Answer 23

The isotopes are:
13 6C and 14 6C

14 7N is not an isotope because it is a different element (nitrogen not carbon).

Question 24

State two pieces of information required to calculate the relative atomic mass of an element.

Answer 24

Two pieces of information required to calculate the relative atomic mass of an element are:

The mass numbers of each isotope.

The (relative / percentage) abundances of each isotope.

Question 25

State the equation for Ar in terms of the percentage abundance and mass of isotopes A and B.

Answer 25

The equation for calculating relative atomic mass in terms of the percentage abundance and mass of isotopes A and B is:

Question 26

True or False? The relative atomic mass of an element can be calculated using the atomic numbers and relative abundances of all its isotopes.

Answer 26

False. The relative atomic mass of an element is calculated using the mass numbers and relative abundances of all its isotopes.

Question 27

In terms of isotopes, what is abundance?

Answer 27

In terms of isotopes, abundance is the amount of each isotope present in a sample of an element.

Question 28

True or False? Relative atomic mass is calculated by adding the mass numbers of all isotopes.

Answer 28

False. Relative atomic mass is calculated by: Multiplying the abundance of each isotope by its mass Adding these numbers together Then, dividing this value by the total abundance.

Question 29

How can you recognise isotopes from their chemical symbol?

Answer 29

Isotopes have the same symbol and same atomic numbers but different mass numbers.

Question 30

After calculating the Ar, how would you identify an element?

Answer 30

After calculating the Ar, you would identify an element by looking for the value on the Periodic Table. For example, Ar = 23. On the Periodic Table, the element with an Ar of 23 is sodium.

Question 31

Calculate the relative atomic mass of an element using this information about its isotopes: Isotope 1: Mass = 71, abundance = 39% Isotope 2: Mass = 69, abundance = 61%

Answer 31

The relative atomic mass of the element is: [(71 x 39) + (69 x 61)] / 100 = 69.8 or 70

Question 32

True or False? Isotopes display different chemical characteristics.

Answer 32

False. Isotopes display the same chemical characteristics.

Question 33

What determines the chemical characteristics of an atom?

Answer 33

The chemical characteristics of an atom are determined by the number of electrons in the outer shell.

Question 34

What is a mass spectra used for?

Answer 34

Mass spectra is used to determine the relative atomic mass of an element from its isotopes.

Question 35

True or False? The element has a relative atomic mass between 71 and 72.

Answer 35

False. The as a relative atomic mass between 70 and 71 because there is a greater abundance of the isotope with a mass of 70 than 72.

Question 36

Use the mass spectrum to calculate the relative atomic mass of the element.

Answer 36

The relative atomic mass of the element is: Ar = (121 x 57.2) + (123 x 42.8) / 100 = 121.9

Question 37

Calculate the relative atomic mass of boron using its mass spectrum.

Answer 37

The relative atomic mass of boron is: (19.9 x 10) + (80.1x11)/100 = 10.8

Question 38

The mass spectrum of an element is shown below. How many isotopes are present in this sample?

Answer 38

There are three isotopes present in this sample as there are three peaks.