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Chem Mr D > Atomic Structure > Flashcards

Atomic Structure Flashcards

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1
Q

What did Democritus discover?

A

Atoms couldn’t be split.

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2
Q

What did John Dalton discover?

A

Came up with theories about what made up different elements.

Determines atoms were tiny particles (like hard spheres) that couldn’t be split, which made up elements.

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3
Q

What did J.J. Thompson discover?

A

Electrons and proved atoms could be split.

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4
Q

What did Rutherford discover?

A

Used experimental work with students to develop nuclear model in which most of mass is concentrated in nucleus with electrons in shells orbiting the nucleus.

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5
Q

What did Niels Bohr discover?

A

Electrons in atoms could only travel along certain shells.

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6
Q

What did James Chadwick discover?

A

Experiment to show existence only neutrons.

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7
Q

What are PEN number?

A

Proton, electrons and neutron numbers.

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8
Q

What does a nucleus contain?

A

Protons + neutrons

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9
Q

What surrounds the nucleus?

A

Orbitals

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10
Q

Why do atoms have no electric charge?

A

Because they contain the same number of protons + electrons

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11
Q

What is the atomic number?

A

Number of protons

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12
Q

What is the mass number?

A

Protons + neutrons

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13
Q

How to work out number of neutrons?

A

Mass no. - atomic no.

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14
Q

What determines the types of atom?

A

Atomic number

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15
Q

Isotopes definition

A

Atoms with same number of protons but different electrons

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16
Q

How to work out relative atomic mass?

A

(Percent x mass)(percent x mass) / total percent

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17
Q

What can the time of flight mass spectrometry be used for?

A
  • find abundance + mass of each isotope in an element so we can determine it’s relative atomic mass
  • find relative molecular mass of substances made of molecules
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18
Q

What are the 4 stages of the time of flight mass spectrometry?

A

1) ionisation
2) acceleration
3) flight tube
4) detection

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19
Q

What happens in the time of mass spectrometry?

A
  • Particles of the substance are ionised to form 1+ ions which are celebration so they all have the same kinetic energy
  • the time taken to travel a fixed distance is then sued to find the mass of each ion in the sample
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20
Q

What are the 2 techniques on ionisation?

A 
Electron impact (electron ionisation)
Electrospray ionisation
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21
Q

What happens in electron impact?

A
  • sample vaporised
  • high energy electrons fired at it from electron gun
  • this knocks off one else torn from each particle forming 1+ ion
  • 1+ ions attracted towards negative electric plate where they are accelerated
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22
Q

What is an election gun?

A

A hot wire filament with a current running through it that emits electrons

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23
Q

Equation for election impact

A

X + e- -> X+ + 2e-

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24
Q

What is the electron impact technique used for?

A

Used for elements + substances with low formula mass

25
Q

How does electrospray ionisation work?

A
  • sample dissolved in a volatile solvent (water/methanol etc)
  • this is injected through fine hypodermic needle to give fine mist (aerosol)
  • needle tip attached to positive terminal of high voltage power supply
  • particles ionised by gaining a proton from solvent as they leave needle producing XH+ ions
  • solvent evaporated away while XH+ ions attracted towards negative plate where they are accelerated
26
Q

What is electrospray impact used for?

A
  • substance with higher molecular mass

- known as ‘soft’ ionisation technique as fragmentation rarely takes place

27
Q

Acceleration explanation

A

Positive ions accelerated is king electric field so they all have same kinetic energy

28
Q

Kinetic energy calculation

A

1/2 mass x velocity squared

29
Q

Kinetic energy of particles unit

A

Joules

30
Q

Mass of particle units

A

Kg

31
Q

Velocity of particle unit

A

m/s-1

32
Q

Velocity equation

A

Square root of 2KE/m

33
Q

What does velocity of each particle in time of mass spectrometry depend on?

A

Mass

Heavier = slower

34
Q

Flight tube explanation

A
  • positive ion travels through home in negatively charged plate into tube
  • time of flight depends on mass /velocity
  • ions set off along flight tube at same time
  • lighter ions travel faster + start to separate our
  • lightest ions ready detector first
35
Q

2 Time equations

A

Distance / velocity of particle

36
Q

What is time of flight proportional to?

A

square root of mass of ions

37
Q

Detection explanation

A
  • positive ions hit negatively charged electric plate
  • ions then discharged by gaining electrons from plate
  • movement of electrons generated + electric current is measured
  • current size gives a measure of number or ions hitting plate
38
Q

What does the mass spectrum show?

A

The mass to charge (m/z) ratio + abundance of each ion that reached detector

39
Q

Why is the mass to charge the mass of each ion?

A

Because all ions are produced by electrospray ionisation + most ions have a 1+ charge

40
Q

How is a mass spectrum generated?

A

A computer using data

41
Q

Relative abundance of an isotope definition

A

the percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element.

42
Q

Relative atomic mass (Ar) calculation

A

Mass of all isotopes/ abundance of all isotopes

43
Q

Time of flight calculation 2

A

Mass in one mole /1000/ 6.02 x 10 to the power 23

44
Q

What is avagadros number?

A

6.02 x 10 to the power of 23

45
Q

What unit is distance?

A

Metres

46
Q

Speed calculation

A

Distance/ time

47
Q

Isotopes definitions

A

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

48
Q

Why do isotopes of the same elements have the same chemical properties?

A

Because they have the same number of elector shell

49
Q

Why is the first ionisation energy of magnesium higher than that of sodium?

A
  • more protons
  • same shielding
  • stronger nuclear charge
50
Q

Relative atomic mass definition

A

the ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12.

51
Q

Electron structure 1

A

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

52
Q

What is Pauli’s principle?

A
  • no more than 2 electrons can occupy the same orbital

- 2 electrons in same orbital must have opposite spins

53
Q

What is Aufban’s principle?

A

Electrons fill lower energy atomic orbitals before filling higher energy ones

54
Q

What is Hund’s rule of maximum multiplicity?

A
  • every orbital in a sub shell is singly occupied with one electron before any one orbital is doubly occupied
  • all electrons in singly occupied orbitals have the same spin
55
Q

How is the electron structure different with Ti + Fe?

A

can’t get rid of 4s2

56
Q

How is the electron structure different with Cr?

A

Electron moves from 4s2 so it becomes 4s1 3d5 due to electron pair repulsion

57
Q

How is the electron structure different in Cu?

A

Goes from 4s2 to 4s1 3d10 because elements is more stable with full 10 orbital radius ether than full 2 orbital

58
Q

How are electrons arranged?

A

Electron shells (energy levels) with sub shells (sub levels)

59
Q

How to identify successive ionisation energy?

A

Bigger jump between numbers of each ionisation energy

Chem Mr D (8 decks)

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