1.1 atomic structure

Question 1

what are the relative charges and masses of the sub atomic particles

Answer 1

proton- 1and +1
neutron- 1and 0
electron- 1/2000 and -1

Question 2

what is an isotope? do isotopes have the same chemical properties why?

Answer 2

an atom of the same element with the same number of protons but different number of neutrons. electron number and arrangement is the same so chemical properties are the same.

Question 3

what are the different atomic models?

Answer 3

Dalton- solid spheres
Thomson- Plum pudding
Rutherford- alpha scattering
Bohr- electrons in fixed shells. shells have fixed energy. Absorb radiation when electrons move out and emit when they move in.radiation has fixed frequency
Others- discovered not all electrons in same shell have same energy so discovered subshells

Question 4

what is relative atomic mass?

Answer 4

the weighted average off the masses of elements isotopes relative to 1/12 of the mass of a carbon-12 atom

Question 5

What is relative isotopic mass?

Answer 5

mass of and atom of an isotope where an atom of a carbon-12 is exactly 12.

Question 6

what is the equation for Ar?

Answer 6

(mass A x %abundance)+ ( mass B x %abundance) / 100

Question 7

What is a mass spectrometer?

Answer 7

an analytical method used to find the Ar or Mrs of one or more substances present in a sample.
used to quantify the abundance of know substances in a sample.

Question 8

What is step 1 in a mass spectrometer? why is this step needed?
what are the two types?

Answer 8

ionisation- so it can be accelerated by an electric field and detected. all ions have a +1 charge
electrospray ionisation
electron impact ionisation

Question 9

Describe electrospray ionisation

Answer 9

used on elements and low Mr compounds
sample dissolved in solvent and pushed through a small nozzle at hight pressure
high voltage applied causing particles to gain H+ ion
solvent is removed and leaves gas of + ions
X(g) + H+ -> XH+ (g)

Question 10

Describe electron impact ionisation

Answer 10

used of high Mr compounds like proteins
sample is vapourised
Electron gun used to fire high energy electrons at it
Knocks off an electron from each particle so they become +1 ions
X(g) ->X+ (g) + e-
equation?

Question 11

What is the second part of mass spec?

Answer 11

Acceleration
Positive ions accelerated by an electric field
All ions gain same kinetic energy but lighter ions experience greater acceleration

Question 12

What is the 3rd part of mass spec?

Answer 12

Ion drift
ions enter region with no electric field
drift through it at same speed they left the electric field so lighter ions drift faster

Question 13

What is the 4th part of mass spec?

Answer 13

detection
lighter ions travel faster in drift area so reach detector sooner
detector detects current when ions hit- size off current is proportional to abundance of ion
records how long each type of ion took to pass through ion drift
this data is used to calculate mass/ charge values needed to produce mass spectrum

Question 14

What is a mass spectrum?
what does each line show?
what is m/z

Answer 14

type of chart produced by mass spectrometer with m/z or mass/charge on x and % abundance on y

A diff isotope if the sample was an element

the mass to charge ratio. charge is +1 so can assume x axis is relative isotopic mass

Question 15

what can you use mass spectrum to tell?

Answer 15

identify elements as you can see the isotopes
find Ar by multiplying %abundance by m/z adding them up and /100. if graph says relative abundance not % then divide by total relative abundance as may not =100

if using electrospray, minus 1 from mass as it includes H+

Question 16

What is a subshell?
what do they contain?
what are these?

Answer 16

Parts of shells as all electrons in shells dont all have same energy. s,p,d,f
They contain diff numbers of orbitals each holding up to 2 electrons
an orbital is where you have a 95% chance of finding an electron

Question 17

what are 3 ways of showing electron configuration?

Answer 17

subshell notation- shows principal quantum number, subshell and no of electrons
Arrows in boxes- each box is an orbital. arrows in diff directions are electrons
energy level diagrams- show energy of electrons in orbitals, no of elevtrons and their arrangemetn

Question 18

What are the rules for working out electron arrangement?

Answer 18

aufbau principle- electrons fill up lowest energy subshells first so 4s filled up before 3d
Hund’s rule- electrons fill orbitals in subshells singly before they start sharing
for the config of ions from s and p blocks, just + or - electrons from highest energy occupied subshell

Question 19

Which 2 elements dont fit the pattern? why?

Answer 19

copper and chromium
they donate an electron from 4s subshell to 3d as they are happier having a more stable full/ half full d subshell

Question 20

which electrons get lost first when transition metals become ions?

Answer 20

4s electrons lost before 3d

Question 21

What is a transition metal? are all d-block elements transition?

Answer 21

a d-block element that forms at least 1 oxidation state with a partially full d-subshell
no. sc and zn arent transition metals

Question 22

what is ionisation energy? what is the equation? what does lower ionisation energy mean? units?

Answer 22

energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions X(g)-> X+(g) + e-
lower ionisation energy means easier to form ion
KJmol-1

Question 23

what factors affect ionisation energy?

Answer 23

nuclear charge- more protons means more + charged nucleus so stronger attraction to electrons
distance from nucleus- attraction falls off with distance
shielding- more electrons between outer shell and nucleus means less attraction

Question 24

what is second ionisation energy?

Answer 24

energy needed to remove and electron from each ion in 1 mol of gaseous 1+ ions
X+(g)->X2+(g) + e-

Question 25

Why is 2nd ionisation energy higher than 1st?

Answer 25

electron being removed from +ion so needs more energy
electron config plays a role in how much larger it is eg in Li, first electron is removed from 2s1 but second from 1s2 so closer to nucleus

Question 26

What are successive ionisation energies?

Answer 26

each time you remove an electron from the nucleus, there is a successive ionisation energy. you can remove all leaving only the nucleus
X(n-1)(g)-> Xn+(g) + e-

Question 27

what happens to ionisation energy down group 2? what does this prove?

Answer 27

decreases.
proves shells exist as each element down has extra shell so more shielding and electrons further away so less attraction

Question 28

what happens to ionisation energies across periods?

Answer 28

increases due to extra proton causing more + nucleus
all electrons roughly same energy level even if diff orbitals so less extra shielding

Question 29

Which groups have dips in ionisation energies when going across the period

Answer 29

drop between 2 and 3- Mg is larger than Al as Al’s outer electron is in 3p not 3s so is further from nucleus. 3p has additional shielding from 3s. these factors override nuclear charge

drop between 5 and 6- shielding is identical and electron is removed from same orbital but in group 5, it is removed from singly occupied orbital and in group 6, orbital with 2 electrons which are already repelling

Question 30

how can you find the group and electronic structure of an element using ionisation energies?

Answer 30

group- ie increases within each shell- big jumps occur when a new shell is broken into as electrons are removed from closer to the nucleus
find group by seeing how many electrons removed before first big jump
electronic structure- work right to left and count how many points before each big jump to find how many electrons in each shell