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AQA Chemistry AS level and A level > 1 Atomic structure > Flashcards

1 Atomic structure Flashcards

1
Q

what is the charge,mass and location of a proton?

A

charge: +1
mass: 1
location: in nucleus

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2
Q

what is the charge,mass and location of an electron?

A

charge: -1
mass: 1/1840
location: around the nucleus in shells

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3
Q

what is the charge,mass and location of a neutron?

A

charge: 0
mass: 1
location: in nucleus

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4
Q

what is the name given to protons and neutrons?

A

nucleons

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5
Q

what force hold protons and neutrons together?

A

nuclear force

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6
Q

what force holds protons and electrons together?

A

electrostatic forces of attraction

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7
Q

what is an atomic number?

A

number of protons

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8
Q

what is the mass number?

A

number of protons +number of electrons

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9
Q

why is the mass of an atom made up of protons and neutrons and not electrons?

A

the nucleons make up most of the mass as electrons don’t weigh much and have little effect on mass of the atom

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10
Q

define isotopes

A

atoms with the same mumber of protons but different neutron number

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11
Q

explain why isotopes of the same element have identical propeties

A

they have the samer electronic configuration and the electronic configuration determines ther chemical propeties of an element

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12
Q

explain why we assume that there are the same number of protons and electrons in an atom

A

they have opposite charges of the same size and the atom is neutral

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13
Q

why do atoms of different isotopes of the same elementy vary in mass number

A

they have different number of neutrons in their nuclei

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14
Q

define relative atomic mass

A

average mass of an atom of an element on a scale where an atom of carbon-12 is 12

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15
Q

define realtive molecular mass

A

average mass of a molecule on a scale where an atom of carbon -12 is 12.

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16
Q

explain how a mass spectrometer works

A

ionisation: sample is vapourised. An electron gun is used to fire high energy electrons at it knocking one electrons off each particle becoming +1 ions
acceleration: positively charged ions are accelerated by electric field.all have the same KE.lighter ions end up moving faster than heavier ions

ion drift: ions enter region with no electric field.ions drift through it.lighter ions drift faster than heavier ions

Detection: lighter ions reach detector first before heavier ions as they are travelling faster.Detector detects charged particles and a mass spectrum is produced

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17
Q

what does a mass spectrum tell us

A

gives accurate information about relative isotopic mass and also about the relative abundance of isotopes.
Mass spectrometer can be used to identify elements.
and to determine relative molecular mass.

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18
Q

what is another name for shells

A

energy levels

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19
Q

how many electrons can be held in an orbital

A

1,2 no more

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20
Q

what are the different oribtals

A

S-orbitals
P-orbitals
D-orbitals
F-orbitals

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21
Q

how many orbitals does each type contain

A

S-one
P-three
D-five
F-seven

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22
Q

how many electrons can be held in each type of orbital

A

S-two
P-six
D-ten
F-fourteen

23
Q

what is the shape of each type of orbital

A

S-spherical

P-Dumbell

24
Q

what are the rules of orbital fillings

A

orbitals fill in order of increasing enrgy.Electrons pair with opposite spins.Orbitals with the same energy are occupied first

25
Q

explain the rule of orbitals filling in order of increasing energy

A

1s is filled first
for n=2 shell,filling order is :2s,2p
for n=3 shell filling order is 3s,3p,3d

26
Q

where odes the orbital filling rule cause confusion

A

the 3d sub-shell has higher energy than 4s.So the 4s fills before the 3d

27
Q

expalain the rule of electron pairs with opposite spin

A

electrons are negatively charged and repel one another electrons have spin up or spin down
if electrons have opposite spin,the charge repulsion is counteracted eough for both to be in the orbital

28
Q

explain the rule of orbitals with the same nergy are occupied singly first

A

within a sub shell,the orbitals have the same energy.One electron ocuupies each orbital before pairing begins.This prevents repulsion until no unocuppied orbitals remian

29
Q

what ius the shell number reffered to as

A

principal quantum number

30
Q

what happens in terms of energy sub-shells when forming ions

A

the highest energy sub-shells lose or gain electrons

31
Q

where are the S block elements on the periodic table and what do they do and form in order to get an inert gas configuration

A

Thery are groups 1 and 2 and lose 1 or 2 electrons to form cations

32
Q

where are the P block elements on the periodic table and what do they do and form in order to get an inert gas configuration

A

Thery are groups 5,6and 7 and they gain 1,2 or 3 electrons to form anions

33
Q

where are the D block elements on the periodic table and what do they do and in order to get an inert gas configuration

A

they lose s and d electrons to form cations

34
Q

why don’t group 0 need to lose,gain or share electrons

A

they have completely filled s and p shells and their full sub shells make them inert

35
Q

chromium and copper dont fill their shells in the same way as other atoms.Explain the differences using electronic configuration

A

chromium donates one of its 4s electrons to the 3d sub shell because it prefers having a more stable half full d sub shell Cr(24 electrons):1S2 2S2 2P6 3S2 3P6 4S2 3D6

copper donates one of its 4s electrons to the 3d sub shell because it prefers having a more stable full d sub shell Cr(24 electrons):1S2 2S2 2P6 3S2 3P6 4S1 3D10

36
Q

define ionisation energy

A

energy reqired to remove a mole of electrons from a mole of atoms in the gaseuous state

37
Q

define 1st ionisation energy

A

energy required to remove one mole of electrons from one mole of gaseuos atoms

38
Q

define 2nd ionisation energy

A

energy required to remove one mole of electron from each ion in 1 mole of gaseuos 1+ions

39
Q

what is an equation for the nth successive ioniation energies

A

X^(n-1)+ —>X^n+ + e^-

40
Q

explain how nucleaur charge affects ionisation energy and state how it changes across a period

A

nucleuar charge increases acroos a period :the more protons there are in the nucleus the more positively charged the nucleus is and the stronger the electrostatic force of attraction this decreases the atomic raduis because the electrons are being pulled inwards towards the nucleus so more energy is needed to remove thje outer electron so ioniation energy is high

41
Q

explain how the distance between the outer electron and the nucleus affects ionisation energy and state how it changes down a group

A

distance increases down the group the more strongly attrac ted the elecron is to the nucleus the greater the electrostatics force of attrac tion between the outer elkectron and the nucleus is and so more energy is needed to remove the outer electron so ionisation energy is high

42
Q

explain how sheilidng affects ionisation energy and state how it changes down a group

A

increases down the group.As number shells increases the electrostatic force attraction decreases this meaqns less energy is needed to remove the outer electron so ionisation energy is low

43
Q

state and explain the general trend in ionsisation energy across a period

A

ionisation energy increases across a period although shielidng stays constant nucleuar charge(no. protons) increases this causes the atomic raduis to decrease across the period.The outer electron is more strongly attrcated to the nucelus and so the electrostatic force of attrcation increases therefore a lot of energy is needed to remove the outer electron

44
Q

state and explain the general trend in ionsisation energydown a group

A

ionisation energy decreases because the increase in nucleuar charge is outwieghed by the increase in sheilding this increases the atomic raduis down the group the outer electron is furhter away from the nucelus and the electrostatyic force of attraction is decreasing so less energy is required to remove the electron

45
Q

generally there is an increase in the 1st ionisation energy across a period.However,the energy decreases as you go from group 2 to group 3.Why?

A

the electron lost from group 3 is from the p orbital,while the one lost from group 2 is from the s orbital.The p orbital is higher nergyand better protected by shielding than the s orbital,so it requires less energy to remove

46
Q

why do successive ionisation energies increase within each shell

A

electrons are being removed from an increasingly positive ion so theres less repulsion amongst the remaining electrons so they are held more strongly by the nucelsu

47
Q

what do the big jumps show in successive ionisation energy graphs of an elemtn

A

shows a new shell is being broken into and shows and electron is being removed from a shell closer to the nucelsu

48
Q

how do you work out the group number in succesive ionisation energies of an element graph

A

count how many electrons are being removed before the first big jump

49
Q

how do you work out the electronic configuration of an element in its succesive ionisation energies graph

A

from right to left count how many points there are before each big jump to find out how many electrons are in each shell

50
Q

explain why it is necessary to ionise molecules when measuring their mass in TOF spectrometer

A

ions,not molecules,will interact with and be accelerated by an electric field and only ions will create a current when hitting the detector

51
Q

expalin why the second ionisation of boron is higher than the first ionisation energy of boron

A

the electron is being removed from a positive ion therefore needs more energy

52
Q

explain why the ionisation energy of every element is endothermic

A

energy is required to overcome the attraction between the electron and the nucleus

53
Q

explain how the detetctor in a mass spectrometer enables the abundance of an isotope to be meausred

A

the ions hit the detector and cause current the bigger the current the more of that isotope is proportional to abundance

54
Q

explain how first and successive ionisation energies in
Period 3 (Na–Ar) and in Group 2 (Be–Ba) give evidence
for electron configuration in sub-shells and in shells.

A

there is a drop between groups 5 and 6.Phosphoros and sulfur atoms have identical shielding and the electron is being removed from a 3p orbital hwoever for phosphorous the electron is being removed from a singly-occupied 3p orbital whereases in sulfur the electron is being removed from a 3p orbital containing two electrons the repulsion between two electrons in an orbital means the electrons are easier to remove from the shared orbitals gving evidence for electronic strucutre

there is a drop between groups 2 and 3 aluminiums outer electron is in a 3p orbital rather than 3s the 3p orbital has slightly higher energy than the 3s orbital so the electron is to be found further form the nucleus .The 3p orbital has additional sheiling provided by the 3S2 electrons.Both of these factors are strong enough to overeide the effect ofd the increased nucleuar charge resulting in the ionisation nergy dropping.This pattern in ionisation energies provide evidence for the theory of electrons in sub shells.

AQA Chemistry AS level and A level (12 decks)

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