1 atomic structure

Question 1

which letter is used to represent the atomic number?

Answer 1

Z

Question 2

what does the atomic number tell us about an element?

Answer 2

the number of protons

Question 3

what letter represents the mass number?

Answer 3

A

Question 4

how do you calculate the mass number?

Answer 4

number of protons + number of neutrons

Question 5

what is a positive ion called?

Answer 5

cation

Question 6

what is a negative ion called?

Answer 6

anion

Question 7

define isotope

Answer 7

isotopes are atoms with the same number of protons but a different number of neutrons

Question 8

do isotopes have the same chemical properties?

Answer 8

yes

Question 9

why do isotopes have the same chemical properties?

Answer 9

same number of electrons/same electron configuration

Question 10

define ionisation energy

Answer 10

the amount of energy needed to remove a mole of electrons from a mole of atoms in the gaseous state

Question 11

what is the first ionisation energy of potassium?

Answer 11

K(g) -> K+(g) + e-

Question 12

why are second ionisation energies of some elements higher than the first?

Answer 12

the ion already has a positive charge

Question 13

what shape is an s orbital?

Answer 13

spherical

Question 14

what shape is a p orbital?

Answer 14

dumbbell

Question 15

what is an orbital?

Answer 15

region within an atom that can hold up to two electrons with opposite spins

Question 16

where do we find orbitals?

Answer 16

in each subshell within each shell

Question 17

how many electrons does an s sub shell hold?

Answer 17

2

Question 18

how many electrons does a p sub shell hold?

Answer 18

6

Question 19

how many electrons does a d sub shell hold?

Answer 19

10

Question 20

what would be the relationship between 2 electrons in the same orbital in terms of their spin?

Answer 20

have opposite spin as they repel eachother because both are negative

Question 21

what are the two types of ionisation for a mass spectrometer?

Answer 21

electron impact and electrospray

Question 22

describe electron impact

Answer 22

1. sample is vaporised and high energy electrons are fired at it from an electron gun
2. this knocks off one electron from each particle forming a 1+ ion

Question 23

describe electrospray ionisation

Answer 23

1. sample dissolved in a volatile solvent and injected through hypodermic needle to give a fine mist
2. tip of needle attached to positive terminal of a high voltage power supply
3. particles gain a proton

Question 24

what does the mass spectrometer measure?

Answer 24

1. relative abundance
2. mass/charge ratio

Question 25

give the 6 steps of TOF mass spectrometer

Answer 25

1. vacuum 2. ionisation 3. acceleration 4. ion drift 5. detection 6. data analysis

Question 26

describe the vacuum stage of TOF

Answer 26

the entire machine is a vacuum inside to prevent any of the particles colliding with air molecules

Question 27

describe ionisation for TOF

Answer 27

two methods where the sample particle gain a positive charge

Question 28

describe acceleration in TOF

Answer 28

the positive ions are attracted to a negatively charged plate (amount they accelerate depends on m/z ratio) once accelerated all ions have same kinetic energy

Question 29

describe ion drift in TOF

Answer 29

some of the ions pass through a hole in negatively charged plate and form a beam of particles that drift apart because they’re all travelling at different speeds

Question 30

describe detection for TOF

Answer 30

different ions arrive at detector at different times. TOF is recorded and as each ion hits the detector it gains and electron which generates a current

Question 31

why are the sample particles ionised in TOF?

Answer 31

so they can be accelerated towards plate and so they generate a current when hitting the detector

Question 32

what is the trend in ionisation energy across period 3?

Answer 32

1. general increase because across period 3 there is a greater nuclear charge 2. so same amount of shielding so a greater attraction between nucleus and outer electron

Question 33

how does the ionisation energy change down a group?

Answer 33

atomic radius increases so more shielding and weaker attraction from nucleus to electrons in outer shell. ionisation energy decreases down the group