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chem > Atomic Structure > Flashcards

Atomic Structure Flashcards

1
Q

why do isotopes of the same element have the same chemical properties

A

they have the same electron configuration

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2
Q

state the different atomic models in chronological order

A

john dalton- solid sphere model
j.j thomson- plum pudding model
ernest rutherford- nuclear model
niels bohr-planetary model (current)
erwin - quantum model

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3
Q

summarise the properties of the subatomic particles

A

proton neutron electron
relative mass 1 1 1/1840
relative charge +1 0 -1

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4
Q

what does the charge of an atom show

A

numbers of electrons gained/lost

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5
Q

why do isotopes have different physical properties

A

they have different numbers of neutrons so they have different masses

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6
Q

describe what evidence was found to support Rutherford’s model

A

-rutherford fired He^2+ ions (alpha particles) at a sheet of gold foil, most went through to other side but small amount bounced back
-when these ions were detected behind the gold foil he concluded that most of the atom was empty space
-when a small number of ions were detected in front of the gold foil he concluded that the atom had a small positive nucleus

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7
Q

what are the key differences between Thomson’s and Bohr’s model

A

-the bohr model has a positive nucleus
-the bohr model has protons and neutrons in the nucleus
-bohr’s model has electrons in shells/energy levels and these orbit the nucleus

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8
Q

where did the evidence to support the electrons being arranged in shells come from

A

from measuring ionisation energies

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9
Q

define ionisation energy

A

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

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10
Q

write an equation for the first ionisation energy of potassium

A

K (g)→K+ (g) + e-

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11
Q

what 3 factors will influence ionisation energy

A

nuclear charge (num of protons)
distance from nucleus
shielding

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12
Q

what are the series of ionisation energies known as

A

SUCCESSIVE ionisation energies

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13
Q

what happens to the IE when an electron is removed from a new shell

A

there’s a large increase in IE as the electron being removed is closer to the nucleus

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14
Q

which element has the highest 1st IE

A

Helium because it has the least amount of shells and shielding than any other atom so it will have the strongest attraction between its outer electron and nucleus so lots of energy s needed to remove its electron.

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15
Q

why is Li a bigger atom than Be

A

-they are on the same period so they have similar shielding however
*Be has more protons than Li so it has a stronger attraction between the outer electron and nucleus therefore
-t goes closer to nucleus.

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16
Q

why is Li a bigger atom than He

A

-it has more shells than He so there’s more shielding
-so there’s a weaker attraction between outer electron and nucleus as there’s a larger atomic radius
-so He will go closer to nucleus

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17
Q

why is Li+ a smaller ion than F-

A

-F- has more shells than Li+ so it has a greater distance and more shielding
-so there’s a weaker attraction between its outer electron and nucleus
-so its bigger

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18
Q

where are orbitals found

A

within each shell there’s a sub shell and within each subshell we find orbitals

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19
Q

what is an orbital

A

its a region within an atom which can hold up to two electrons with opposite spins

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19
Q

how many orbitals is there in;
-the s sub-shell
-the p sub-shell
-the d sub-shell

A
  • 1
    -3
    -5
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20
Q

what is the maximum number of electrons in each shell;
-1
-2
-3
-4

A

-2
-8
-18
-32

21
Q

what is the shape of an s orbital

A

circle

22
Q

what is the shape of the p orbital

A

like an eight/infinity sign

23
Q

which orbitals are the lowest energy ones

A

the ones closer to the nucleus

24
Q

which electron is determined the highest energy

A

the outer most electron because its furthest from nucleus

25
Q

give the electron configuration of potassium

A

1s2 2s2 2p6 3s2 3p6 4s1

26
Q

give the electron configuration for chromium

A

1s2 2s2 2p 3s2 3p6 4s1 3d5

27
Q

give the electron configuration for copper

A

1s2 2s2 2p6 3s2 3p6 4s1 3d10

28
Q

give electron configuration for a CU2+ ion

A

1s2 2s2 2p6 3s3 3p6 3d9

29
Q

why does B have a dip in 1st IE

A

-in Be the outer electron is on 2s2 and on B its on 2p1
-2p is higher energy than 2s
-therefore there’s going to be a weaker attraction between the outer electron and nucleus

30
Q

why does O have a dip in 1st IE

A

-there are a pair of electrons in O on 2p orbital
-the electrons will repel so less energy is needed to remove electron

31
Q

how does IE change down a group

A

IE decreases because as you go down a group the atom size increases and there are more shells so there’s more shielding. therefore the distance between the nucleus and outer electron increases and the attraction weakens, so less IE is needed.

32
Q

what does a mass spectrometer measure

A

-relative abundance
-mass/charge ratio (m/z)

33
Q

what are the steps for mass spectrometer

A

-insert sample in vacuum chamber and ionise
-acceleration
-ion drift
-ion detector
-data analysis

34
Q

why is the entire mass spectrometer in a vacuum

A

to prevent any particles being tested colliding with molecules from the air

35
Q

what are the methods of ionisation

A

-electron impact and electrospray ionisation

36
Q

describe the acceleration stage in flight tube

A

-positive ions are attracted to a negatively charged plate and accelerate towards it at constant KE
-the acceleration depends on their mass to charge ratio

37
Q

describe the ion drift

A

-ions will form a beam of particles ad travel along flight tube, towards detector
-ions have different velocities and they are separated due to their mass
-heavier ions travel slower
-lighter ions travel faster
-therefore they are all detected at different times

38
Q

describe detection

A

-different m/z ions arrive at detector/negatively charged plate
-once an ion hits the detector, it gains an electron and this floe of electron generates a current which is proportional to the abundance

39
Q

describe data analysis

A

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

40
Q

why are sample particles ionised

A

-so they can be accelerated towards the negatively charged plate
-to generate a current when hitting the detector

41
Q

how is the ion accelerated

A

-positive ions are attracted to the negatively charged plate to a constant KE

42
Q

what does each peak on a mass spectrometer graph represent

A

a different isotope

43
Q

escribe electron impact ionisation

A

-sample is vaporised
-high energy electrons are fired from an electron gun
-which is a hot wire filament with a current that emits electrons
-high energy electrons knock off one electron from sample forming a positive ion

44
Q

which ionisation technique is used for elements and substances with low formula mass

A

-electron impact
-and causes the (molecular) ion to break down into fragments

45
Q

give general equation for electron impact ionisation

A

X (g) → X+ (g) + e-

46
Q

describe electrospray ionisation

(this process is for substances with higher molecular mass like proteins)

A

-sample is dissolved in volatile solvent
-and injected through a fine hypodermic needle to give a fine mist (aerosol)
-top of needle has a high voltage power supply
-and particles are ionised by gaining a proton (H+)

47
Q

give the general equation for electrospray ionisation

A

X( g) + H+ → XH+ (g)

48
Q

calculate the peaks of Br2
79-81
50% each

A

79-79=1/4
79-81 and 81-79 = 2/4
81-81= 1/4

25%=158
25%=162
50%=160

49
Q

what is the structure to find highest IE when both one atom’s electrons are on p3 and the other on p4

A
  • there is a pair of electrons on _p orbital
  • these electrons will repel
  • so less energy is needed to remove electron
50
Q

what is the structure to find higher IE when each atom’s outer electron is on a different sub-level on same shell

A
  • state location of outer electron
  • _p is higher energy than _s
    -compare attraction between outer electron and nucleus

chem (9 decks)

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