Chemistry Unit 1

Front 1

definition of atomic structure

Back 1

the atom consist of nucleus and electrons.
the nuclues contain protons and neutons.Electron move around nucleus in shell.

Front 2

atomic number

Back 2

this is the number of proton in the nucleus of an atom

Front 3

Atomic mass
also called mass number

Back 3

the sum of protons and neutrons in the nucleus of an atom

Front 4

why atom is nutral

Back 4

proton number is equal to the electron number, proton have +1 charge and electron have -1. so it is neutral.

Front 5

definition of isotope

Back 5

these are atoms of same element with different number of neutrons, but the number of electrons and protons is the same

Front 6

state what chemical difference there will be , if any, between 85Rb and 87Rb(mass number)

Back 6

there will be no chemical difference because of same number of electrons involved in chemical reaction

Front 7

movement of particle in electric field.

Back 7

neutron have no charge, it is neutral therefore is go straight out and not attract to the electric field.
electron is negative charge hence attract to positive plate.electron have a small m/z ratio hence deflect more easily
proton have postive charge hence it attract to the negatibe plate.proton hace gtreater m/z ratio hence harder to deflect (smaller deflection)

Front 8

mass spectrometer
1. why sample need to be vaporised

Back 8

the sample is first vaporised to allow free movement of particles through spectrometer

Front 9

2. explain how the gaseous atom are ionised in a mass spectrometer

Back 9

the sample ionised when fast moveing electrons from electron gun knock into the atom and cause one or more electron to be remove . positive ion then form

Front 10

3.where acceleration takes place? and explain how it work?

Back 10

electric field
two metal plates, one is positive and one is negative with a hole in the middle of them. the first plate is positive and second plate is negative which causes the attraction of the positive ions to accelertate and focus the particle into a fine beam.

Front 11

4. deflection

Back 11

the ions are deflected in the magnectic field, the amount of deflection depends upon
1.the mass of the particle, lighter one deflect more easily
2.the charge on the particle,the greater the charge the greater the deflection.
3.the strength of magnetic field.

Front 12

5.dectection

Back 12

the charged particles hit s the detector create a current which is amplified and then a spectrum is produce

Front 13

why vacuum pump involved in the mass spectrometer

Back 13

vacuum pump to remove air to allow particles to move freely

Front 14

Greater number of particles hit the detector

Back 14

greater the current-higher abundance

Front 15

half value of m/z

Back 15

some atoms, occassionaly lose 2 electrons at ionisation chamber,this is causes two plus ions formed, this is extremely rare since this is very difficult for positive ions to lose an electron since the attraction of the positive charge for the outer electron is more stronger. this is why the peak is so small, the value of the m/z will half value of the plus charge.

Front 16

definition of relative atomic mass

Back 16

this is the average mass of an atom compare to 1/12th mass of carbon-12 atom.

Front 17

definition of relative molecular mass

Back 17

this is the average mass of a molecule compare to 1/12th mass of carbon 12 atom.

Front 18

on the mass spectrometer graph, what labelled on the y axis?
what lablled on the x axis

Back 18

y axis---abundance

x axis---m/z

Front 19

fragmentation

Back 19

when compounds are ionised in a mass spectrometer the loss of an electron can weaken the bond, this means the molecules more likely to fragment and split up. Other smaller ions are produces, which cause number of peaks.

Front 20

the molecular ion

Back 20

the molecular ion is the ion form when the whole molecule loses one electron. the RMM is the value for the peak with the highest number of m/z. when non of them had been fragmented.

Front 21

what abundance show

Back 21

shows how stable the ion is

Front 22

how abundance of an isotope is determined?
name the relative part?

Back 22

Detector
the charged particles hit the detector create a current which is amplified and then a spectrum produce. The Greater the Current, the Greater the Abundance

Front 23

explain the electron arrangement in terms of energy

Back 23

the first shell is closest to the nucleus , is lowest in energy, as the shell get further from the nucleus they increase in energy.

Front 24

why 4s subshell is before 3d subshell

Back 24

4s subshell have lower energy than 3d subshell. when filling subshell,the lowest energy subshell is filled first.

Front 25

configuration

Back 25

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 5d

s--2 p--6 d--10

Front 26

p and d subshell

Back 26

electron fill subshell in order of energy,in a 'p' or 'd' subshell. electrons go in separately before they are paired up.Each subshell must be filled before the next one is started. they spin in opposite direction of orbital because of the repulsion.

Front 27

what is the electron arrangement of chromium

Back 27

the electron arrangement of chromium is actually the stability associated with full and half full subshell, so the arrangment is:

Front 28

what is the electron arrangement of

Back 28

the electron arrangement of cooper is actually stability associated as it have full and half full subshell.

Front 29

4s - 3d ionisation

Back 29

electrons are lost in the 4s subshell before the 3d, when the 3d subshell is being filled these electrons repel the 4s one further from the nucleus,making higher in energy

Front 30

definition of ionisation energy

Back 30

this is the energy required to remove one mol of gaseous atom to form one mole of positive gaseous ions.

Front 31

equation of first ionisation

Back 31

-

Front 32

which four factors affect the ionisation energy

Back 32

sheilding
electron arrangement
effective nuclear charge
distant

Front 33

what is the trend in ionisation down the group

Back 33

as you down a group, the ionisation energy decreases because increase distance between the nucleus and the outer electrons which weakened the bond and more shells that sheild the outer electron and the nucleus . these factors make it easier to lose an electron.

Front 34

is ionisation endothermic or exothermic? and why

Back 34

-Bendo( breaking is endo)
ionisation energy is endothermic, because energy is required to break a bond. they are positive values. they are positive values going down a group, the value become less positive.

Front 35

what's the trend in ionisation across a period.

Back 35

the ionisation enerygy general increase across a period , this is because the effective nuclear charge increase ,but the sheilding stay the same. this makes the attraction between nucleus and outer electron stonger

Front 36

the first ionisation graph across the period 3

Back 36

.

Front 37

why does aluminium have a lower ionisation energy than Mg

Back 37

-
-
the outer electron of aluminium is in the higher energy level 3p subshell further from the nucleus making it easier to lose.

Front 38

why does sulfur have a lower ionisation energy than phosphorus

Back 38

-
-
in sulphur ,there's a pair of electrons in 3p subshell,which repel each other ,making it easier to lose an electron.

Front 39

Why does magnesium have a higher ionisation energy than sodium

Back 39

the effective nuclear charge in magnesium is greater than in sodium and the shielding stay the same so it become more difficult to remove an electron.

Front 40

Second ionisation energy

Back 40

This is the energy required to remove one mole of electron from one mole of gaseous positive ions to form one mole of dipositive ions.

Front 41

Equation of second ionisation energy

Back 41

.

Front 42

Explain why the ionisation energy of every element is endothermic.

Back 42

Energy is required to break the bond,so it is endothermic.
-Bendo