1.1 Atomic Structure

Question 1

What is atomic mass?

Answer 1

Number of protons in an atom (and therefore also electrons)

Question 2

What is mass number?

Answer 2

Total number of protons and neutrons

Question 3

What are isotopes?

Answer 3

Isotopes are atoms with the same number of protons but different numbers of neutrons, and therefore a different mass number

Question 4

Name the stages of the mass spectrometer

Answer 4

Ionisation, acceleration, ion drift (in the flight tube), detection, data analysis

Question 5

What must you account for when calculating the relative atomic mass from mass spectra?

Answer 5

The relative abundances of isotopes

Question 6

How many electrons does each atomic orbitals hold?

Answer 6

s holds 2, p holds 6, d holds 10

Question 7

Name the sub atomic particles which make up an atom

Answer 7

Proton, electron,neutron

Question 8

What is ionisation energy?

Answer 8

The energy needed to remove one mole of electrons from one mole of atoms in a gaseous state

Question 9

What is the general trend in ionisation energy across a period?

Answer 9

General increase alone a period due to increasing nuclear charge

Question 10

What are the relative masses and charges of the sub atomic particles?

Answer 10

Neutron: 1, 0 Proton, 1, +1 Electron, 1/1840, -1

Question 11

What holds electrons and protons together in an atom?

Answer 11

Electrostatic forces of attraction

Question 12

How do you calculate the mass number?

Answer 12

number of protons + number of neutrons (the total number of nucleons)

Question 13

Define the term relative atomic mass

Answer 13

The average mass of an atom compared to the mass of 1/12 of a carbon 12 atom

Question 14

Explain why a time of flight mass spectrometer is kept under a vacuum

Answer 14

To prevent the ions that are produced colliding with molecules from the air

Question 15

What causes the ions to accelerate through a mass spectrometer?

Answer 15

They are attracted by a negatively charged plate

Question 16

Give the electronic configuration, showing all the sub levels, of a calcium atom

Answer 16

1s2 2s2 2p6 3s2 3p6 4s2

Question 17

What is the relative mass of an electron?

Answer 17

1/1840

Question 18

What is meant by the term first ionisation energy?

Answer 18

The enthalpy change needed to move an electron from the outer most shell of an atom

Question 19

Why does the first ionisation energy generally decrease as you go down a group?

Answer 19

Down a group there is more electron shielding because there are increasing numbers of electron shells. Therefore the outer electrons are further from the nucleus and thus easier to remove.

Question 20

Why does the first ionisation energy generally increase as you go across a period?

Answer 20

As you move across a period, the atomic radius decreases. This means the outer electrons are closer to the nucleus and more strongly attracted to the center. Therefore, it becomes more difficult to remove the outermost electron.

Question 21

What holds electrons and protons together in an atom?

Answer 21

Electrostatic forces of attraction

Question 22

How do you calculate the mass number?

Answer 22

number of protons + number of neutrons (the total number of nucleons)

Question 23

Define the term relative atomic mass

Answer 23

The average mass of an atom compared to the mass of 1/12 of a carbon 12 atom

Question 24

Explain why a time of flight mass spectrometer is kept under a vacuum

Answer 24

To prevent the ions that are produced colliding with molecules from the air

Question 25

What causes the ions to accelerate through a mass spectrometer?

Answer 25

They are attracted by a negatively charged plate

Question 26

Give the electronic configuration, showing all the sub levels, of a calcium atom

Answer 26

1s2 2s2 2p6 3s2 3p6 4s2

Question 27

What is the relative mass of an electron?

Answer 27

1/1840

Question 28

What is meant by the term first ionisation energy?

Answer 28

The enthalpy change needed to move an electron from the outer most shell of an atom

Question 29

Why does the first ionisation energy generally decrease as you go down a group?

Answer 29

Down a group there is more electron shielding because there are increasing numbers of electron shells. Therefore the outer electrons are further from the nucleus and thus easier to remove.

Question 30

Why does the first ionisation energy generally increase as you go across a period?

Answer 30

As you move across a period, the atomic radius decreases. This means the outer electrons are closer to the nucleus and more strongly attracted to the center. Therefore, it becomes more difficult to remove the outermost electron.