Atomic Structure

Question 1

Relative atomic mass

Answer 1

The average mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12

Question 2

Relative molecular mass

Answer 2

The average mass of a molecule of an element or compound compared to 1/12th the mass of an atom of carbon-12

Question 3

Isotope

Answer 3

Atoms of the same element with the same number fo protons but a different number of neutrons

Question 4

Mass number

Answer 4

The total number of protons and neutrons in the nucleus

Question 5

Atomic number

Answer 5

The number of protons in the nucleus

Question 6

First ionisation energy

Answer 6

The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

Question 7

Second ionisation energy

Answer 7

The energy required to remove 1 mole of electrons from 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions

Question 8

Orbital

Answer 8

The region where an electron is most likely to be found

Question 9

How many electrons does energy level 1 have

Answer 9

2 electrons

Question 10

How many electrons does energy level 2 have

Answer 10

8 electrons

Question 11

How many electrons does energy level 3 have

Answer 11

18 electrons

Question 12

How many electrons does energy level 4 have

Answer 12

32 electrons

Question 13

How many electrons does orbital p have

Answer 13

2

Question 14

How many electrons does orbital s have

Answer 14

2

Question 15

What is the shape and max number of electrons in sub shell s

Answer 15

2 - Max núm of electrons
Shape of sub shell- spherical

Question 16

What is the max num of electrons in sub shell p

Answer 16

Max num of electrons - 6

Question 17

Sub shell d max num of electrons

Answer 17

Max num of electrons 10

Question 18

Sub shell f max number of electrons

Answer 18

Max number- 14

Question 19

Concentration (g dm^-3) equation

Answer 19

Mass of solute(g) / volume of solution (dm^3)

Question 20

Concentration (mol dm^-3)

Answer 20

Amount of solute(mol) /vol of solution(dm^3)

Question 21

Concentration (mol dm^-3)
(Conversion to gdm^-3)

Answer 21

Concentration (g dm^-3)/ molar mass (g mol^-1) aka mr

Question 22

Relationship between empirical and molecular formula

Answer 22

Empirical formula is the simplest whole number ratio of atoms of each element in a compound.

Molecular formula is the actual number of atoms of each element in a compound.

Question 23

the lower the ionisation energy…

Answer 23

the easier it is to form an ion

Question 24

name the 3 factors affecting ionisation energy

Answer 24

• Nuclear charge
  -atomic radius
  -shielding

Question 25

what affect does nuclear charge have on ionisation energy

Answer 25

more protons mean more positively charged nucleus is and the stronger the attraction of electrons

Question 26

what affect does atomic radius have on ionisation energy

Answer 26

attraction falls off rapidly with distance. electron closer will be more attracted than those further

Question 27

what affect does shielding have on ionisation energy

Answer 27

when number of electrons between outer electrons and nucleus increase the outer electrons feel less attraction to nuclear charge. lessening of the pull of the nucleus by inner shells of electrons is called shielding.

Question 28

what does high ionisation energy mean

Answer 28

high attraction between electron and the nucleus so more energy is needed to remove electrons

Question 29

why do the ionisation energies increase for increasingly positive ions

Answer 29

because there is less repulsion amongst remaining electrons so they are held more strongly by the nucleus

Question 30

Describe the ionisation stage of electron impact

Answer 30

- high energy electrons are fired at the sample from an electron gun - this knocks off one electron from each atom or molecule to form a 1+ ion : X(g) → X+(g) + é

Question 31

Describe the ionisation stage electronspray ionisation

Answer 31

- the sample is dissolved in a volatile solvent -it’s injected through a fine hypodermic needle at a very high voltage - the particles gain a proton and become ions : X(g) + H+(g) → XH+(g)

Question 32

describe the acceleration of ions stage

Answer 32

the ions are accelerated using an electric field so that all the ions have the same kinetic energy

Question 33

describe the separation of charges ions stage

Answer 33

- ion drift the ions then enter the flight tube - ions with different masses have a different time of flight -the lighter ions travel faster and take less time to reach the detector

Question 34

describe the detetection stage

Answer 34

- the detector is a negatively charged plate- a current is produced when the ions hit the plate- the more ions

Question 35

Explain why the second ionisation energy is greater than the first ionisation energy

Answer 35

Electron removed from positive ion

Question 36

Explain why ionisation energy of every element is endothermic

Answer 36

Energy is needed to overcome attraction between negative electron and the nucleus

Question 37

State an explain the general trend in first ionisation energies of period 3 elements from sodium to chlorine

Answer 37

Bigger nuclear charge Electrons closer to nucleus Smaller atomic radius So increase

Question 38

Started how oxygen deviates from general trend in first ionisation energies

Answer 38

Two pairs of electrons in (3)p orbital which repel each other

Question 39

Why does aluminium deviate from the first ionisation energy trend from Na to Ar

Answer 39

Electron further away from nucleus so less energy needed

Question 40

Why is second ionisation energy of sodium greater than second ionisation energy of magnesium

Answer 40

Na looses electron from a lower orbital less shielding in Na

Question 41

Why does sodium have a smaller melting point than magnesium

Answer 41

Na fewer protons smaller attraction between nucleus and delocalised electrons

Question 42

Explain why it is necessary to ionise molecules when measuring their mass in a TOF mass spectrometer.

Answer 42

Ions will interact with and be accelerated by an electric field Only ions will create a current when hitting the detector