Atomic structure Flashcards

1
Q

Relative atomic mass

A

the weighted mean of the mass of an elements atoms
to 1/12 the mass of carbon-12

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2
Q

Relative isotopic mass

A

the mass of an atom of an isotope
relative to 1/12 the mass of carbon-12

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3
Q

1st stage of mass spectrometry

A

ionisation
- particles are ionised via bombardment with high energy electrons
- generates positive ions

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4
Q

2nd stage of mass spectrometry

A

ions are accelerated by an electric field

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5
Q

3rd stage of mass spectrometry

A

deflection
- ions pass through strong magnetic fields
- lighter ions are deflected more

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6
Q

4th stage of mass spectrometry

A

detection
- ions are detected electronically as currents
- size of current indicates abundance

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7
Q

How is the mass of an isotope detected using time of flight

A
  • all ions are accelerated so they have equal kinetic energy
    KE = 1/2MV2
  • ions with different velocities will have different masses
  • velocity can be calculated using time and distance
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8
Q

What is the first ionisation energy definition

A

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

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9
Q

Equation for 1st ionisation energy

A

X(g) -> X+(g) + e-

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10
Q

Factors that affect ionisation energies

A
  • nuclear charge
  • distance of outer electrons from nucleus
  • shielding
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11
Q

What is the trend in ionisation energies across a period

A

increases
- greater nuclear charge so greater attraction between electrons and nucleus

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12
Q

What is the trend in ionisation energies down a group

A

decreases
- more shells so shielding and distance between nucleus and electrons increases

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13
Q

How many electrons does each quantum shell hold

A

1st - 2
2nd - 8
3rd - 18

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14
Q

What shape are s orbitals

A

spherical

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15
Q

What shape are p orbitals

A

dumbbell shaped

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16
Q

What is an orbital

A

an area in space that has a 95% chance of finding an electron

17
Q

Explain why the 1st ionisation energy of group 2 is less than that of a group 3

A

the outermost electron from a group 2 is removed from an s subshell rather than a p subshell which is closer to the nucleus

18
Q

Explain why the 1st ionisation energy decreases from phosphorus to sulfur

A

in sulfur the p electros are paired for the first time
- repulsions are set up between paired electrons
- this reduces energy needed to remove the electron

19
Q

Which groups are in the s block

A

groups 1 + 2

20
Q

Which groups are in the p block

A

groups 3 - 8

21
Q

Which groups are in the d block

A

transition metals

22
Q

How can you identify the group of an element from ionisation energies

A

big jumps in ionisation energies indicate that an electron is being removed from a subshell closer to the nucleus
group 1 - jump between IE 1 and IE 2

23
Q

What is periodicity

A

chemical trends that repeat across periods

24
Q

Which properties show periodicity

A
  • melting and boiling points
  • atomic radius
25
Why does melting and boiling points increase from group 1 - 3
metals which bond metallically group 1 - 1e- per atom delocalised group 2 - 2e- delocalised results in stronger attraction between delocalised electrons and + ions - requires more energy to overcome
26
Why are melting and boiling points the highest in group 4
form giant covalent structures - strong covalent bonds between atoms
27
Why does melting and boiling points decrease in group 5 - 7
simple molecular substances with weak intermolecular forces
28
Why is there a slight increase in the melting and boiling points of phosphorus and sulfur
phosphorus tends to be p4 sulfur is s8
29
What is atomic radius
distance from the centre of nucleus to the boundary of the electron cloud - difficult to determine
30
What are the two ways to find atomic radius
- covalent radius - van der waal's radius (two atoms touching eachother rather than overlapping)
31
Why does atomic radius decrease along a period
nuclear charge increase so greater attraction to electrons, so the electron cloud is pulled in tighter - attraction to nuclear far outweighs repulsions between electrons
32
Why does atomic radius increase down a group
more shells