Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-Level Chemistry > Atomic Structure > Flashcards

Atomic Structure Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

what is the plum pudding model?

A

atoms consisted of sphere of positive charge, with small negative charges distributed evenly within it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the nuclear model?

A

atom consists of a small, dense central nucleus surrounded by orbiting electrons in electron shells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

relative mass of an electron?

A

1/1840

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how to calculate maximum number of orbiting electrons that can be held by any single shell?

A

2n² where n is the number of the shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what letter represents mass number?

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what letter represents atomic number?

A

Z

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is relative atomic mass?

A

the mean mass of an atom of an element compared with one twelfth of the mean mass of an atom of carbon-12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is an isotope?

A

Isotopes are atoms with the same number of protons, but different numbers of neutrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why do isotopes have similar chemical properties?

A

same electronic structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

why do isotopes have slightly varying physical properties?

A

different masses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why may a mass spectrometer be used?

A

to determine the isotopes present in a sample of an element + therefore identify elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why must a tof mass spectrometer be under a vacuum?

A
  • to prevent air molecules from colliding with ions
  • air particles could ionise + register on the detector
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

list the 4 steps in tof mass spectrometry

A

1) ionisation
2) acceleration
3) ion drift/deflection
4) detection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

List the 2 methods of ionisation

A

electron impact
electro spray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe electron impact ionisation

A
  • a vaporised sample is injected at low pressure
  • electron gun fires high-energy electrons at sample
  • this knocks out an outer electron forming positive ions with different charges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

when would electron impact ionisation be used?

A
  • elements + substances with low formula mass
  • can cause larger organic molecules to fragment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe electro-spray ionisation

A
  • sample dissolved in a volatile, polar solvent
  • injected through fine hypodermic needle giving a fine mist or aerosol
  • tip of needle has high voltage
  • proton gained at tip of needle from the solvent
  • solvent evaporates away while ions move towards negative plate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

when would electro-spray ionisation be used?

A
  • for larger organic molecules
  • softer conditions means fragmentation doesn’t occur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe the acceleration stage of tof mass spectrometry

A

positive ions are accelerated towards a negatively charged detection plate to a constant kinetic energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what determines the velocity of the ions in the acceleration stage of tof mass spectrometry?

A
  • mass
  • lighter particle = greater velocity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

describe the ion drift/deflection stage of tof mass spectrometry

A
  • ions deflected by a magnetic field into a curved path
  • radius of path determined by charge + mass
  • positive ions with smaller m/z values will have the same kinetic energy as those with larger m/z + will move faster
  • heavier particles take longer to move through drift area
  • ions distinguished by different flight times
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

describe the detection stage in tof mass spectrometry

A
  • when positive ions hit the negatively charged detection plate, they gain an electron producing a flow of charge
  • greater abundance of the species = greater charged produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is m/z?

A

mass/charge ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the m/z of 24Mg2+ ?

A

12
mass=24
charge = 2
24/2 = 12

25
Q

what is an atomic orbital?

A
  • a region around the nucleus that can hold up to two electrons with opposite spins
  • all orbitals in a subshell have the same energy
26
Q

what is an electron?

A

a cloud of negative charge

27
Q

what is the shape of an s orbital?

A

spherical

28
Q

which electron shells contain s orbitals? how many?

A

every electron shell contains a single s orbital

29
Q

what is the shape of a p orbital?

A

dumbell

30
Q

which electron shells contain p orbitals? how many?

A

every electron shell apart from the first contains 3 p orbitals

31
Q

which electron shells contain d orbitals? how many?

A

every shell apart from shells 1 and 2 have 5 d orbitals

32
Q

which electron shells contain f orbitals? how many?

A

shells 4 and above have 7 f orbitals

33
Q

what is a subshell/level

A

all of the orbitals of the same type in the same shell

34
Q

as you move away from the nucleus, does the energy of the subshells increase or decrease?

A

increase

35
Q

what are the rules for filling atomic orbitals?

A

1) orbitals with the lowest energy are filled first
2) can have up to 2 electrons in the same orbital but they must have opposite spins
3) electrons are put into individual orbitals with the same energy before they are paired

36
Q

why are electrons put into individual orbitals first before they are paired?

A

electrons in the same orbital repel

37
Q

how is an electron in an orbital represented?

A

half arrow in the direction of the electron’s spin

38
Q

how is electron configuration written?

A

1s1,2s2,2p6,3s2,3p6,4s2,3d10
the first number represents the shell number
the letter represents the orbital
the other number represents the number of electrons in the orbital

39
Q

why does the 4s subshell fill before the 3d subshell?

A

before it is filled, the energy of the 4s subshell is less than the energy of the 3d subshell

40
Q

which elements are exceptions to the electron configuration rules?
why?

A
  • chromium and copper
  • 3d subshells more stable when half or completely full
  • for chromium by having only 1 electron in 4s subshell it can have half full 3d subshell, so more stable
  • for copper, by having only 1 electron in 4s subshell, it can have completely full 3d subshell, so more stable
41
Q

when an ion forms, where do the electrons gained/lost go?

A

the subshell with the highest energy gains or loses electrons

42
Q

where do d block elements lose electrons from? why?

A
  • 4s subshell
  • 4s subshell has a higher energy than 3d subshell once it contains electrons
43
Q

what is the first ionisation energy?

A

the energy needed to remove one mole of electrons from one mole of atoms in their gaseous state to form one mole of 1+ ions (also in their gaseous state)

44
Q

what is the second ionisation energy?

A

the energy needed to remove one mole of electrons from one mole of 1+ in their gaseous state to form one mole of 2+ ions (also in their gaseous state)

45
Q

write an equation for the first ionisation energy of Mg

A

Mg -> Mg+ + e-

46
Q

write an equation for the second ionisation energy of Mg

A

Mg+ -> Mg2+ + e-

47
Q

list 3 factors that affect ionisation energy

A

1) atomic radius
2) nuclear charge
3) shielding

48
Q

what is atomic radius? how does it affect ionisation energy?

A
  • distance between nucleus and the outermost electrons
  • as atomic radius increases, the force of attraction between the positive nucleus and the outer electrons decreases which lowers the ionisation energy
49
Q

how does nuclear charge affect ionisation energy?

A

greater number of protons = greater force of attraction between the outer electrons and nucleus therefore increasing the ionisation energy

50
Q

how does shielding affect ionisation energy?

A
  • electrons in outer shell are repelled by electrons in inner shells
  • this shielding effect reduces the attraction between the outer electrons and the nucleus and therefore lowers the ionisation energy
51
Q

why does first ionisation energy decrease going down a group?

A
  • atomic radius increases so outer electrons are further away from nucleus
  • number of internal energy levels also increases so there is more shielding between the nucleus and the outer electrons
  • therefore going down a group, attraction between the nucleus and outer electrons decreases, resulting in a lower ionisation energy
52
Q

how does first ionisation energy change across a period?

A

tends to increase

53
Q

why does first ionisation energy increase across a period?

A
  • number of protons increases across a period (nuclear charge) which increases the attraction between nucleus and electrons
  • atomic radius also decreases across a period
  • therefore outer electrons are more attracted to the nucleus causing the first ionisation energy to increase across the period
54
Q

why don’t boron and oxygen fit the trend in first ionisation energy across a period?

A
  • boron has a lower 1st i.e than Be as the outer electron is in the 2p subshell which has higher energy than the 2s subshell so it takes less energy to remove the puter electron of boron compared to the outer electron of Be
  • oxygen has one orbital in the 2p subshell that contains a pair of electrons - these repel each other so it takes less energy to remove one of these electrons than if they were in separate orbitals
55
Q

what do the peaks on the mass spectra of an atom represent?

A

the different isotopes of the atom and their abundance

56
Q

what is the formula to calculate Ar from the mean mass of isotopes?

A

[(m/z 1 x abundance 1) +( m/z 2 x abundance 2)/ total abundance

57
Q

what do the peaks on a mass spectra of a molecule represent? why?

A
  • molecular ion often breaks down + loses atoms forming fragments - represented by the peaks
  • last peak on the mass spectrum represents mass of the whole molecule + therefore the Mr of the molecule
  • may be a small peak (m+1) due to presence of isotopes
58
Q

what is relative isotopic mass?

A

the mean mass of an isotope of an atom, compared with one twelfth of the mean mass of an atom of carbon-12

59
Q

what is relative molecular mass?

A

weighted mean mass of a molecule of a compound or element compared with one twelfth of the mass of an atom of carbon 12

A-Level Chemistry (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions