3.1 Atomic structure

Question 1

what is the charge of a proton

Answer 1

+1

Question 2

what is the mass of a proton

Answer 2

1

Question 3

what is the charge of a neutron

Answer 3

0

Question 4

what is the mass of a neutron

Answer 4

1

Question 5

what is the charge of an electron

Answer 5

-1

Question 6

what is the relative mass of a electron

Answer 6

very small
1/1800
negligible

Question 7

what composes an atom

Answer 7

proton
neutron
electron `

Question 8

what is the mass number

Answer 8

the total number of protons and neutrons in an atom

Question 9

what is found within the nucleus

Answer 9

protons
neutrons

Question 10

what is the atomic number

Answer 10

the number of protons in the nucleus.
+ number of electrons

Question 11

how is mass number represented by

Answer 11

A

Question 12

how is the atomic number represented as

Answer 12

Z

Question 13

how do you find the number of neutrons in an atom

Answer 13

mass number [A] - atomic number[Z]

Question 14

what are isotopes

Answer 14

atoms with the same number of protons but different number of neutrons

Question 15

why do isotopes have similar chemical properties

Answer 15

they have the same electronic structure

Question 16

why do isotopes have varying physical properties

Answer 16

they have different masses

Question 17

define Relative Isotopic Mass

Answer 17

the mass off an atom of an isotope compared to 1/12 of the mass of one atom of carbon-12

Question 18

define relative atomic mass

Answer 18

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

Question 19

define relative molecular mass

Answer 19

the average mass of a molecule compared to 1/12 of the mass of one atom of carbon-12

Question 20

what does the mass spectrometry provide

Answer 20

-gives information about relative isotopic mass
- relative abundance of isotopes

Question 21

what are the stages of the time of flight mass spectrometry

Answer 21

• Ionisation
• Acceleration
• Ion drift
• ion detection (data analysis)

Question 22

what is the process of ionisation

Answer 22

turns an atom into an ion

Question 23

what 2 ways can we ionise an atom

Answer 23

electron impact
electrospray ionisation

Question 24

what occurs during electron impact

Answer 24

high energy electrons are fired from an electron gun at sample.
This knocks out an outer electron
and forms a positive ion.

Question 25

what state is the sample in

Answer 25

vapourised

Question 26

what does electron impact do to a molecule

Answer 26

fragmentation

Question 27

what is electrospray ionisation

Answer 27

- the sample is dissolved in a volatile solvent. - This is injected through a fine needle giving a mist. - Tip of needle has a high voltage - Sample gains a proton

Question 28

what is the kinetic energy of the ions when they go through the acceleration

Answer 28

they have constant kinetic energy

Question 29

how and why do ions accelerate

Answer 29

the plates have a negative charge the ions accelerate by an electrical field

Question 30

what type of particle has the fastest velocuty

Answer 30

lightest particle

Question 31

when the ions accelerates what does it gain

Answer 31

it gains speed and kinetic energy

Question 32

what is ion drift

Answer 32

when the ions drift down the flight tube within a vaccum

Question 33

what is ion detection

Answer 33

when the ion hits the detector - an electron is picked up - electric current is created

Question 34

what does the size of the electric current suggest when the ion hits the metal plates ?

Answer 34

the size of the current is proportional to the abundance of the species

Question 35

what is the nuclear charge

Answer 35

the collective charge of all protons in the nucleus

Question 36

what does a high nuclear charge mean to the electrons

Answer 36

the electrons are more attracted to the nucleus

Question 37

what is the trend in the nuclear charge across a period

Answer 37

it increases

Question 38

what is the trend in the nuclear charge down a group

Answer 38

the nuclear charge increases down the group

Question 39

what happens to the atomic radius when the nuclear charge increases

Answer 39

the atomic radius decreses

Question 40

why does the atomic radius decrease when the nuclear charge increases

Answer 40

the shells are closer

Question 41

what is the relationship between the nucleus and the electrons suggest

Answer 41

the greater the distance between the electron and the nucleus the weaker the forces of attraction

Question 41

what happens when the number of shells increases

Answer 41

- the shielding increases

Question 42

what is the overall trend in the shielding across a period

Answer 42

the shielding stays the same across a period

Question 43

what is the overall trend in shielding down a period

Answer 43

theres more shielding and the number of electron energy levels increases

Question 44

what is the definition of ionisation energy

Answer 44

the enthalpy change when one mole of gaseous atoms form one mole of gaseous 1+ ions. And electrons are removed

Question 45

what is the trend in ionisation energy down the group

Answer 45

- decreases down he group - cause the attraction between the outer electrons and nucleus decreases

Question 46

why does the attraction between the outer electron and nucleus decrease with the ionisation energy.

Answer 46

- electrons are further away from the nucleus - more shielding due to the no. of shells

Question 47

what is the trend in ionisation energy across a period

Answer 47

- increases across the period - attraction between outer electrons and nucleus increases

Question 48

why does the attraction between the outer electron and nucleus increase for the ionisation energy across a period

Answer 48

- the nuclear charge increases - shielding stays the same

Question 49

why is the ionisation energy of aluminium lower than the ionisation energy of magnesium

Answer 49

-magnesiums outer electron is in the 3s subshell -Aluminiums outer electron is in the 3p subshell :. increased shielding and further distance from the nucleus

Question 50

explain why the ionisation energy of sulphur is lower than that of phosphorus

Answer 50

there is an electron pair in the 3p orbital so there is greater repulsion :. less energy is needed to remove the electrons

Question 51

Explain why the 2nd IE of chlorine is higher than the first IE of chlorine

Answer 51

the 2nd IE of Cl+ is largeer than the 1st IE cause an electron is rremoved from a positive ion which requires more energy

Question 52

give two reasons why the isotopes are ionised before they can be analysed in a TOT mass spectromemeter. [2 marks]

Answer 52

-so that the ions are accelerated by an electric field towards the negatively charged plates -ions create a current when the hit the detector, by picking up an electron

Question 53

basically the debiaitons are the same for periods 2 and 3 in correspondance to the position. for example the deviaitions of Be and b are the same as the ones of Mg and Al. just swap the 3p orbital to like a 2p orbital. The deviations of N and O is the same as the ones for P and S

Question 54

what is the unit for mass in the moles equation

Answer 54

grams

Question 54

what is the unit for mass in the TOF equation

Answer 54

kg

Question 55

how are ions detected

Answer 55

+ve ions collide with the detector which causes a current to flow

Question 56

what is ionisation energy

Answer 56

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

Question 57

how is abundance is measured

Answer 57

abundance is dependant on the current. its proportional

Question 58

what deflects the ion

Answer 58

a magnet

Question 59

what is adjusted in order to direct ions of different mass to charge ratio onto the detector

Answer 59

a magnetic field

Question 60

name the equipment used to measure the relative abundance of istopes

Answer 60

mass spectrometer