1 Atomic structure

Question 1

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

Answer 1

charge: +1
mass: 1
location: in nucleus

Question 2

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

Answer 2

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

Question 3

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

Answer 3

charge: 0
mass: 1
location: in nucleus

Question 4

what is the name given to protons and neutrons?

Answer 4

nucleons

Question 5

what force hold protons and neutrons together?

Answer 5

nuclear force

Question 6

what force holds protons and electrons together?

Answer 6

electrostatic forces of attraction

Question 7

what is an atomic number?

Answer 7

number of protons

Question 8

what is the mass number?

Answer 8

number of protons +number of electrons

Question 9

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

Answer 9

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

Question 10

define isotopes

Answer 10

atoms with the same mumber of protons but different neutron number

Question 11

explain why isotopes of the same element have identical propeties

Answer 11

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

Question 12

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

Answer 12

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

Question 13

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

Answer 13

they have different number of neutrons in their nuclei

Question 14

define relative atomic mass

Answer 14

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

Question 15

define realtive molecular mass

Answer 15

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

Question 16

explain how a mass spectrometer works

Answer 16

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

Question 17

what does a mass spectrum tell us

Answer 17

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.

Question 18

what is another name for shells

Answer 18

energy levels

Question 19

how many electrons can be held in an orbital

Answer 19

1,2 no more

Question 20

what are the different oribtals

Answer 20

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

Question 21

how many orbitals does each type contain

Answer 21

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

Question 22

how many electrons can be held in each type of orbital

Answer 22

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

Question 23

what is the shape of each type of orbital

Answer 23

S-spherical

P-Dumbell

Question 24

what are the rules of orbital fillings

Answer 24

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

Question 25

explain the rule of orbitals filling in order of increasing energy

Answer 25

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

Question 26

where odes the orbital filling rule cause confusion

Answer 26

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

Question 27

expalain the rule of electron pairs with opposite spin

Answer 27

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

Question 28

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

Answer 28

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

Question 29

what ius the shell number reffered to as

Answer 29

principal quantum number

Question 30

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

Answer 30

the highest energy sub-shells lose or gain electrons

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

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

Answer 33

they lose s and d electrons to form cations

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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

Question 36

define ionisation energy

Answer 36

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

Question 37

define 1st ionisation energy

Answer 37

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

Question 38

define 2nd ionisation energy

Answer 38

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

Question 39

what is an equation for the nth successive ioniation energies

Answer 39

X^(n-1)+ —>X^n+ + e^-

Question 40

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

Answer 40

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

Question 41

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

Answer 41

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

Question 42

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

Answer 42

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

Question 43

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

Answer 43

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

Question 44

state and explain the general trend in ionsisation energydown a group

Answer 44

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

Question 45

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?

Answer 45

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

Question 46

why do successive ionisation energies increase within each shell

Answer 46

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

Question 47

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

Answer 47

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

Question 48

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

Answer 48

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

Question 49

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

Answer 49

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

Question 50

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

Answer 50

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

Question 51

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

Answer 51

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

Question 52

explain why the ionisation energy of every element is endothermic

Answer 52

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

Question 53

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

Answer 53

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

Question 54

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.

Answer 54

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.