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physical chem > atomic structure (1) > Flashcards

atomic structure (1) Flashcards

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1
Q

what is inside the nucleus

A

protons and neutrons

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2
Q

relative mass & relative charge of a proton

A

1 & +1

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3
Q

relative mass & charge of a neutron

A

1 & 0

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4
Q

relative mass & charge of an electron

A

1/2000 & -1

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5
Q

how did john dalton describe the atom

A

atom was the smallest particle & indivisible

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6
Q

how did JJ Thompson describe the atom & what did he discover

A

discovered: electron
described the atom as a positive charge spread through with negative electrons dispersed

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7
Q

how did Ernest Rutherford describe the atom and how did he come to this conclusion

A

bombarded alpha particles at thin gold foil and some bounced back, discovering the nucleus and describing the atom as a tiny positive nucleus surrounded by mainly empty space in which electrons are moving

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8
Q

What did Neils Bohr discover and how did he describe the atom

A

as rutherford, but electrons moving in energy levels. he discovered electrons move in shells (energy levels)

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9
Q

how did james chadwick describe the model

A

As Bohr, but nucleus contains protons and neutrons

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10
Q

what type of mass spectrometer do we use

A

time of flight mass spectrometer

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11
Q

explain how mass spectrometry works

A
  1. ionised by either electron impact or electrospray ionisation
  2. the positive ions are accelerated using an electric field
  3. the positive ions travel through a hole in the negatively charged plate into a tube
  4. the positive ions hit a negatively charged plate.
  5. current is produced
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12
Q

ions with the same charge have the same _________

A

kinetic energy

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13
Q

will lighter ions be faster or slower than heaver ions when drifting towards the detector

A

faster velocity

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14
Q

how do you determine the mass of the isotope using the mass spectrometer

A

the time taken for the isotope to reach the detector determines the mass of the isotope

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15
Q

how do you determine the abundance of the isotope using the mass spectrometer

A

the size of the currentproduced when the isotope hits the detector

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16
Q

what is the interior of the mass spectrometer made out from

A

vaccum to prevent ions colliding with molecules in the air.

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17
Q

why must a sample containing isotopes must be vaporised and ionised

A

to make it acclerate, to detect the ions.

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18
Q

define mass number

A

the number of protons and neutrons

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19
Q

define relative atomic mass

A

average mass of 1 atom compared to 1/12 of 12C

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20
Q

one change in the operation of the mass spectrometer that will change the velocity of an ion

A

electric field

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21
Q

why is the value calculated on the mz graph thing different from the relative atomic mass given in the periodic table different

A

because the Ar in the periodic table takes account other isotopes

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22
Q

why do isotopes of an element have the same chemical properties

A

because they have the same electron configuration

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23
Q

how are ions formed in a time of flight mass spectrometer

A

electrospray ionisation or electron gun

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24
Q

what is ionisation energy

A

ionisation energy is the minimum energy required to remove the most loosely bound electron

25
Q

name 3 factors that effect ionisation energy

A

atomic radius, number of protons, shielding

26
Q

how does atomic radius effect ionisation energy

A

the smaller the radius the stronger the attraction between the nucleus and electron, so ionisation energy increases

27
Q

how does number of protons effect ionisation energy

A

the more protons the stronger the attraction between the nucleus and electrons, meaning higher ionsiation energy

28
Q

how does shielding effect ionisation energy

A

more shielding means the weaker the attraction between nucleus and electron, so the ionisation energy is decreased

29
Q

how and why does ionisation vary when going down a group

A

electron is easier to remove as there is weaker attraction between the nucleus and electron, so ionisation energy decreases

(there is more shielding and a bigger atomic radius)

30
Q

how and why does ionisation vary when going across a period

A

general increase across period

because:
-smaller atomic radius
-more protons
-stronger attraction between nucleus and electron
-electron more difficult to remove

31
Q

what does electronegativity mean

A

ability of an atom to attract electron density

32
Q

what does first ionisation energy mean

A

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

33
Q

what is electron impact

A

high energy electrons fired at the sample from electron gun

34
Q

what is electrospray ionisation

A
  • sample is dissolved in a volatile solvent

-then injected through a needle at high voltage

-each particle gains H+

35
Q

what happens when an ion hits the detector

A

the ion loses an electron

36
Q

equation for mass (kinetic energy)

A

m = 2KET² / D²

37
Q

equation for time (kinetic energy)

A

t = d x √m / 2KE

38
Q

equation for distance (kinetic energy)

A

d = t x √2KE / m

39
Q

what is adjusted so that each isotope can be detected

A

electric field

40
Q

how does adjustment enable isotopes to be separated

A

deflection depends on mass or m/z

41
Q

how can the mr be obtained from its mass spectrum

A

the mr is the highest mz value

42
Q

what is used to deflect the positive ions

A

magnetic field

43
Q

why does ionisation energy drop at 2-3

A

outer electron is further from the nucleus and is higher in energy, so electron is easier to remove

44
Q

why does ionisation energy drop at 5-6

A

if in p block, electron from, 2 electrons need to pair and the pairing will cause repulsion.

45
Q

meaning of atom

A

smallest part of an element that can exist

46
Q

meaning of atomic nucleus

A

positively charged object composed of protons and neutrons at the center of every atom with one or more electrons orbiting it

47
Q

meaning of atomic number

A

number of protons in the nucleus

48
Q

meaning of electron

A

negatively charged subatomic particle which orbits the nucleus at various energy levels. relative mass of 1/2000

49
Q

meaning of electron configuration

A

the distribution of electrons of an atom in orbitals

50
Q

meaning of isotope

A

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

51
Q

mass number meaning

A

total number of protons and neutrons in the nucleus

52
Q

mass spectrometer meaning

A

a mass spectrometer gives accurate info about relative isotopic mass and also about the relative abundance of isotopes

53
Q

mass spectrometry meaning

A

mass spec can be used to identify elements and determine relative molecular mass

54
Q

neutron meaning

A

neutral subatomic particle present in the nucleus of the atom

55
Q

nuclear charge meaning

A

total charge of all the protons in the nucleus.

56
Q

proton meaning

A

positively charged subatomic particle present in the nucleus of the atom

57
Q

sub- shells meaning

A

electron shells are divided up into sub-shells which have slightly different energy levels. the sub shells have different numbers of orbitals which can each hold up to two electrons

58
Q
A

physical chem (5 decks)

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