1 atomic structure Flashcards

1
Q

which letter is used to represent the atomic number?

A

Z

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2
Q

what does the atomic number tell us about an element?

A

the number of protons

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3
Q

what letter represents the mass number?

A

A

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4
Q

how do you calculate the mass number?

A

number of protons + number of neutrons

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5
Q

what is a positive ion called?

A

cation

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6
Q

what is a negative ion called?

A

anion

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7
Q

define isotope

A

isotopes are atoms with the same number of protons but a different number of neutrons

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8
Q

do isotopes have the same chemical properties?

A

yes

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9
Q

why do isotopes have the same chemical properties?

A

same number of electrons/same electron configuration

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10
Q

define ionisation energy

A

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

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11
Q

what is the first ionisation energy of potassium?

A

K(g) -> K+(g) + e-

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12
Q

why are second ionisation energies of some elements higher than the first?

A

the ion already has a positive charge

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13
Q

what shape is an s orbital?

A

spherical

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14
Q

what shape is a p orbital?

A

dumbbell

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15
Q

what is an orbital?

A

region within an atom that can hold up to two electrons with opposite spins

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16
Q

where do we find orbitals?

A

in each subshell within each shell

17
Q

how many electrons does an s sub shell hold?

A

2

18
Q

how many electrons does a p sub shell hold?

A

6

19
Q

how many electrons does a d sub shell hold?

A

10

20
Q

what would be the relationship between 2 electrons in the same orbital in terms of their spin?

A

have opposite spin as they repel eachother because both are negative

21
Q

what are the two types of ionisation for a mass spectrometer?

A

electron impact and electrospray

22
Q

describe electron impact

A
  1. sample is vaporised and high energy electrons are fired at it from an electron gun
  2. this knocks off one electron from each particle forming a 1+ ion
23
Q

describe electrospray ionisation

A
  1. sample dissolved in a volatile solvent and injected through hypodermic needle to give a fine mist
  2. tip of needle attached to positive terminal of a high voltage power supply
  3. particles gain a proton
24
Q

what does the mass spectrometer measure?

A
  1. relative abundance
  2. mass/charge ratio
25
Q

give the 6 steps of TOF mass spectrometer

A
  1. vacuum
  2. ionisation
  3. acceleration
  4. ion drift
  5. detection
  6. data analysis
26
Q

describe the vacuum stage of TOF

A

the entire machine is a vacuum inside to prevent any of the particles colliding with air molecules

27
Q

describe ionisation for TOF

A

two methods where the sample particle gain a positive charge

28
Q

describe acceleration in TOF

A

the positive ions are attracted to a negatively charged plate (amount they accelerate depends on m/z ratio) once accelerated all ions have same kinetic energy

29
Q

describe ion drift in TOF

A

some of the ions pass through a hole in negatively charged plate and form a beam of particles that drift apart because they’re all travelling at different speeds

30
Q

describe detection for TOF

A

different ions arrive at detector at different times. TOF is recorded and as each ion hits the detector it gains and electron which generates a current

31
Q

why are the sample particles ionised in TOF?

A

so they can be accelerated towards plate and so they generate a current when hitting the detector

32
Q

what is the trend in ionisation energy across period 3?

A
  1. general increase because across period 3 there is a greater nuclear charge
  2. so same amount of shielding so a greater attraction between nucleus and outer electron
33
Q

how does the ionisation energy change down a group?

A

atomic radius increases so more shielding and weaker attraction from nucleus to electrons in outer shell.
ionisation energy decreases down the group