Topic 2 - Atomic structure

Question 1

What is the atomic number?

Answer 1

• the number of protons in the nucleus of an atom

Question 2

What is the mass number?

Answer 2

• the number of protons and neutrons in the nucleus

Question 3

What is the relative atomic mass?

Answer 3

• weighted average of the atomic masses and their relative isotopes

Question 4

What is an isotope?

Answer 4

• atoms of the same element with different mass numbers, but the same atomic number (different number of neutrons)

Question 5

What are the properties of various isotopes?

Answer 5

• same chemical properties

- different physical properties (mass difference)

Question 6

What are ions?

Answer 6

• atoms of elements whose electron number is changed

Question 7

What is a cation?

Answer 7

• a positive ion formed when electrons are lost

Question 8

What is an anion?

Answer 8

• a negative ion formed when electrons are gained

Question 9

What is a mass spectrometer?

Answer 9

• gives information about the isotopic composition of different elements and the structure of molecules

Question 10

What are the five basic operations of a mass spectrometer?

Answer 10

1) vaporisation
2) ionisation
3) acceleration
4) deflection
5) detection

Question 11

What happens during the vaporisation stage in the mass spectrometer?

Answer 11

• vaporised sample is injected to allow individual atoms to be analysed

Question 12

What happens during the ionisation stage in the mass spectrometer?

Answer 12

• hit by high-energy electrons to knock of others and create ions (positive)

Question 13

What happens during the acceleration stage in the mass spectrometer?

Answer 13

• cations attracted to negatively charged plates - accelerated by a magnetic field and pass through a hole in it

Question 14

What happens during the deflection stage in the mass spectrometer?

Answer 14

• cations deflected by magnetic field at 90° to its path - amount of deflection depends on charge/mass ratio

Question 15

What happens during the detection stage in the mass spectrometer?

Answer 15

• cations with particular ratio are detected and a signal is sent to the recorder - strength is a measure of ions with that ratio detected

Question 16

Which ions are most deflected in the mass spectrometer?

Answer 16

• smaller mass

- higher charge

Question 17

When are emission spectra produced?

Answer 17

• when photons are emitted from atoms as excited electrons return to a lower energy level

Question 18

What does the line emission spectrum of hydrogen provide?

Answer 18

• evidence for the existence of electrons in discrete energy levels, which converge at higher energy levels

Question 19

What happens when white light is passed through hydrogen gas?

Answer 19

• an absorption spectrum is produced - this is a line spectrum with some colours from continuous spectrum

Question 20

What is a continuous spectra?

Answer 20

• produces a smooth spectrum of colours from red to violet (when light is passed through a prism)

Question 21

What is an emission spectra?

Answer 21

• formed when excited electrons move to lower energy levels, releasing specific light energies (line spectra)

Question 22

What is an absorption spectra?

Answer 22

• produced when atoms/ion/molecules absorb some light energy, remove it and leave a “gap” in the spectrum

Question 23

How can atoms absorb and emit energy?

Answer 23

• an electron moves into an orbit or higher energy level further from the nucleus when it absorbs energy - the excited state produced is unstable and the electron soon returns to the lowest level (ground state) - the energy this releases is an electromagnetic radiation

Question 24

By what levels are the sub-levels identified by?

Answer 24

• s
• p
• d
• f

Question 25

Which letter(s) identify the 1st sub-level?

Answer 25

- s

Question 26

Which letter(s) identify the 2nd sub-level?

Answer 26

- s, p

Question 27

Which letter(s) identify the 3rd sub-level?

Answer 27

- s, p, d

Question 28

How many electrons are there in sub-level 1?

Answer 28

- sub-level: 1s - maximum number of electrons in sub-level: 2 - maximum number of electrons in level: 2

Question 29

How many electrons are there in sub-level 2?

Answer 29

- sub-level: 2s, 2p - maximum number of electrons in sub-level: 2s: 2, 2p: 6 - maximum number of electrons in level: 8

Question 30

How many electrons are there in sub-level 3?

Answer 30

- sub-level: 3s, 3p, 3d - maximum number of electrons in sub-level: 3s: 2, 3p: 6, 3d: 10 - maximum number of electrons in level: 18

Question 31

How many electrons are there in sub-level 4?

Answer 31

- sub-level: 4s, 4p, 4d, 4f - maximum number of electrons in sub-level: 4s: 2, 4p: 6, 4d: 10, 4f: 14 - maximum number of electrons in level: 32

Question 32

What is the order of filling sub-levels?

Answer 32

- 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d

Question 33

What is a photon?

Answer 33

- a quantum of radiation

Question 34

Where are the s, d, p and f blocks located?

Answer 34

- s: group 1 - 2 - d: group 3 -12 - p: group 14 - 18 - f: bottom bottom line thingy

Question 35

What is the Pauli Exclusion Principle?

Answer 35

- each orbital can hold a maximum of two electrons

Question 36

What is the Aufbau Principle?

Answer 36

- determines the electron configuration of the ground state of an atom of an element - states that electrons are placed into lower energy levels first