unit 2 revision

Question 1

what is the mass of an electron

Answer 1

1/1840

Question 2

what is charge of a proton

Answer 2

+1

Question 3

what is the charge of an electron

Answer 3

-1

Question 4

what is the mass of a neutron and proton

Answer 4

1

Question 5

what is the charge of a neutron

Answer 5

0

Question 6

what force holds together the protons and neutrons in the nucleus?

Answer 6

the strong nuclear force

Question 7

what is an isotope?

Answer 7

an atom of an element with the same number of protons and electrons but a different number of neutrons

Question 8

why do different isotopes of the same element have the same chemical reactivity?

Answer 8

as they have the same electron configuration

Question 9

what is the electron shell rule

Answer 9

2n^2

Question 10

what is the vaccum in a time of flight mass spectrometer?

Answer 10

the whole apparatus is kept under a high vaccum to prevent the ions from colliding with the molecules in the air

Question 11

what is electrospray ionisation?

Answer 11

same dissolved volatile solvent
pushed through needle high pressure
voltage applied causing each atom to lose an electron
solvent removed leaving a gas of unipositive ion

Question 12

what is electron impact ionisation?

Answer 12

the sample is vaporised and high energy electrons are fired at it from an electron gun,which is a hot wire filament with a current running through it that emits a beam of high energy electrons this usually knocks off one electron from each particle forming a +1 ion

Question 13

what is acceleration in a time of flight mass spectrometer?

Answer 13

the positive ions are attracted towards a negatively charged plate and accelerate towards it

Question 14

what type of ions accelerate faster?

Answer 14

lighter ions and more highly charged ions

Question 15

what is ion drift in time of flight mass spectrometer

Answer 15

the ions pass through a hole in the negatively charged plate forming a beam and travel along a tube to a detector

Question 16

what is detection in a time of flight mass spectrometer

Answer 16

when ions with the same charge arrive at the detector the lighter ones are first as they have higher velocities the flight times are recorded and the positive ions pick up an electron from the detector which causes a current to flow

Question 17

what is data analysis

Answer 17

The signal from the detector is passed to a computer which generates a mass spectrum

Question 18

what is an atomic orbital

Answer 18

a region of space around an atomic nucleus where there is a high probability of finding an electron

Question 19

how many electrons can a S subshell hold?

Answer 19

2

Question 20

how many electrons can a P subshell hold?

Answer 20

6

Question 21

how many electrons can a d subshell hold

Answer 21

10

Question 22

how many electrons can a f subshell hold

Answer 22

14

Question 23

how many electrons can an atomic orbital hold?

Answer 23

2

Question 24

what are the three rules for allocating electrons to atomic orbitals

Answer 24

• atomic orbitals of lower energy are filled first/sub-levels of lower energy are filled first
• no orbital can hold more than 2 electrons
• atomic orbitals fill singly before pairing starts because electrons repel each other

Question 25

what is ionisation energy?

Answer 25

the amount of energy required to remove one mol of electrons from one mole of atoms in gaseous state to turn them into one mol of +1 ions

Question 26

name three factors that affect ionisation energy

Answer 26

• electron shielding
• distance from the nucleus
• pull from the nucleus