Atomic Structure Flashcards
Name fundamental particles
Proton neutron electron
Isotope definition
Atoms with the same n.o of pro but diff n.o of neut
why do isotopes have the same chemical properties
same number of electrons
What are electrons arranged into
Principle energy levels
Sub shells
Orbitals
Define principle energy level
The main energy level occupied by electron
Sub shell def
A group of atomic orbitals of the same type within a shell. Split into S P D F dep on location
Orbital def
Sub shells are further split into orbitals that can contain up to 2 e- with opposite spins
(Up ward and downward arrows)
How many sub shells in each principle energy level
n=1 ——> 1s
n=2 —> 2s, 2p
n=3 —> 3s, 3p, 3d
n=4 —> 4s, 4p, 4d, 4f
Periodic table is divided into blocks. What does the block of an element dep on
The sub shell that the outermost electrons are in
How is the periodic table organised and where are the blocks
S block : group 1 + 2
D block: middle section (transition metals)
P block : right of table starting from group 3
Info about s orbital found in s subshell
Spherical shape
Can hold up to 2e-
P orbital
3 p orbitals x,y,z
2 e- each
So subshell holds 6 ELECTRONS
Dumbbell shape
D orbital
5 d orbitals with 2e- each
10 ELECTRONS TOTAL
Order of energy levels from high energy to low
S has the Lowest followed by P then D
Always fill from lowest to highest
What’s special ab 4s subshell
Fills before 3d subshell bc it’s lower in energy
Order of filing up shells
1s, 2s, 2p, 3s, 3p, 4S!!, 3d, 4p, 4d,4f
What is important to remember about filling up orbitals w the same energy eg: three 2p orbitals (xyz)
We put e- into individual orbitals before we pair them
Why are chromium and copper execeptions?
The 3d sub level is more stable when half of completely full so in the case of chromium by having only 1 e- in 4s sub level it can have a half full 3d subshell.
Expected config: …3d4 4s2
Actual: ….. 3d54s1
Short hand version of electronic configuration
Look at noble gas before hand and write tagt first eg sodium would be (Ne) 3s1
What is different about the elements in the d block in terms of configurations for ions and why
When d block elements loose e-
They are lost from the 4s sub shell before the 3d sub shell
- once the 4s subshell contains e- it has a higher energy than the 3d sun shell
First ionisation definition
Energy needed to remove one mole of electrons from one mole of atoms in their gaseous state to form 1 mole of 1+ ions (also in gaseous state)
Second ionisation energy definition
Energy needed to remove one mole of electrons from one mole of 1+ ions in their gaseous state to form 1 mole of 2+ ions also in their gaseous state
Successive ionisation energies
Continual removal of e- and measuring ionisation energy each time
Equations for ionisation energy of mg
First ionisation energy: mg -> mg+ + e-
Second : mg+ -> mg2+ + e-
Third: mg2+ -> mg3+ + e-
Fourth: mg3+ -> mg4+ + e-
Fifth: mg4+ -> mg5+ + e-
(All should have (g) )
How do you know which ionisation energy something is
The ionisation energy is the same as the charge produced
Key idea about strength of ionisation energy
E- in an atom are attracted to the positive protons in nucleus
The greater attraction between the outer electrons and nucleus, the greater the ionisation energy
Factors affecting ionisation energy
1) dist bet nucleus and outermost e-
—> Aka atomic radius, as this increases it weakens the force of attraction bet postive nuc and outer e-
2) charge of nucleus —> e- attracted to +ve nucleus (pro)
⬆️ n.o of pro= ⬆️ force of attraction
3) shielding —> electrons in outer are repelled by e- inner shells, reduced attraction bet outer e- and nuc
So ⬆️shielding= ⬇️ force of attraction= ⬇️ionisation energy req.
Ionisation energies in group 1 trend
As you go down group one number of shells increase = ⬆️ atomic radius= ⬆️dist from nucleus-= ⬇️ ionisation energy needed
What is TOF used for
Used to identify elements, their Ar based on abundance and mass of isotopes. Also can be used to find Mr.
4 main stages of TOF
1) ionisation
2) acceleration
3)ion drift
4) detection
What is an important condition kept in the apparatus
Kept under high vacuum to prevent any ions produced in apparatus reacting with surrounding air
2 ways of ionisation
1) electron impact ionisation
2) electrospray ionisation
What kind of elements is electron impact used for
Elements or substances with a lower molecular mass
Describe electron impact
1) sample vaporised
2) bombarded w high energy e- which are fired from electron gun
3) e- then knocked off forming 1+ ion
Steps after 1+ ion is formed and what are the ions known as
The ions formed are molecular ions
1) attracted toward negative plate
2) then accelerated through mass spec
3) molecular ion can be further broken down/fragmented
These frag can also be accelerated and hit detector causing diff peaks to show up on mass spec produced
What kind of elements are electrospray ionisation used for and whag is unlikely to happen due to whag technique
Substances with a high molecular mass, unlike other method fragmentation unlikely due to soft ionisation technique
Steps of electrospray ionisation
(Sample is) dissolved (in a volatile solvent)
(Injected through) needle/nozzle/capillary at high voltage/positively
charged
Each molecule/particle gains a proton/H
Whag is needle attached to and why
High voltage power supply , so when injected the particles are ionised by gaining proton from solvent
Eg
X(g) + H+ ——> XH+(g)
Next steps of ions after electronspray ionisation
Solvent evaporates and XH+ ions are attracted towards a negatively charged plate which accelerates them through mass spec
Describe 2) acceleration and in terms of KE and velocity
The 1+ ions formed from ionisation are accelerated using an electric field
They’re all accelerated to have the same kinetic energy
So velocity dep on mass
What’s important ab mass of ions during ion drift
Lighter ions move faster reaching detector quicker and heavy ions move slower reaching detector slower
Describe 3) ion drift (in flight tube)
1) The 1+ ions pass through a hole in negatively charged plate and move into flight tube
2) the TOF for each ion dep on velocity
Describe 4) detection
Once they pass through mass spec the 1+ ions will hit a negatively charged detector plate
1) as they hit the plate they gain an e-
2) this discharges the ion
3) current produced
Whagts important ab size of current prod
The size of current is proportional to abundance of ions hitting negative plate and gaining an e-
How is the mad spec produced
The detector plate is connected to a computer which produces mass spec
Why is ionsiation needed
Only ions will create current when hitting detector
Only ions not molecules will interact and will be accelerated by magnetic/electric field
Which fundamental particle won’t be deflected by an electric field
Neutron
Ionisation energies across a period
General increase
Increased nuclear charge which offsets the slighty decreasing atomic radius and shielding stays the same
Ionisation energies across period 3
General increase due to increased nuclear charge = increased attraction.
From mg —> al ionisation energy decreases: e- removed from 3p orbital in al vs 3s orbital in mg. Higher energy level so less attraction due to increased dist
From p—-> s electron removed from electron pair which causes repulsion vs singularly occupied orbital in p. Some- easier to remove.
Ionisation energies across period 2
From berellium to boron ionisation energy decreases. 2p e- removal vs 2s which is at higher energy level so less attraction
From nitrogen to oxygen - electron pair repulsion so e- easier to remove
Why is second ionisation energy of Boron higher than first ionisation energy of boron
removing an electron from 2s subshell
this is closer to the nucleus
so have stronger electrostatic force of attraction so e- harder to remove
Which block in periodic table contains nickel
D block
In terms of struc and bonding why does nickel have a high melting point
Contains positive metal ion lattice surrounded by sea of delocalised electrons with a strong attraction between them that take alot off energy to overcome
Why is nickel ductile
Layers of atoms that can slide over eachother due to weak imf / vdw bet them
What can be adjusted in mass spec to make ions of diff isotopes directed to detector
Magnetic field
Why may ram of sample be diff to ram given in periodic table
Other isotopes present
Equation for Ion X hitting detector
X^+ + e- ——> X
Electron impact
Sample bombarded by high energy electrons from electron gun causing outer electron to be knocked off forming +ve ion
2 measurments recorded in mass spec
Relative abundance
M/z ratio
Why do isotopes if an element have same chemical properties
Have the same electron configuration/ same number of electrons in outer shell
What kind of isotope is deflected the most in magnetic field of mass spec
Ion w lowest m/z
Who and what was the first model of atomic structure
John dalton - atoms are tiny sold indivisible spheres
Second model?
Jj Thompson plum pudding - atoms not indivisible and instead have e- suspended in ball of postive charge .
He discovered electrons
Third model?
1909 - rutherford, hans geiger, Ernest marsden
Gold foil. Postive alpha particles at gold foil if jj correct then particles should deflect. But maj of particles went straight through some deflected so nuclear model prop :
Tiny +ve nuc surronded by cloud of neg charge and atom mostly empty space
Fourth model?
Electron cloud would cause atom to collapse. Neils Bohr proposed e- exist in fixed energy levels
They emit or gain em rad when moving bet energy levels.
Fifth ?
Not all electrons in a shell have the same energy so therefore electrons shells must have further sub shells
Realative isotopic mass
Mass of an atom of an isotope of an elements relative to 1/12th of an atom of carbon - 12
Realative molecular mass
Average mass of a molecule on a scale where an atom of carbon 12 is 12
v= …
d/t
equation to calc mass of ion
avo
——
1000
equation for time of flight
t=d x square root of m
——
2Ek
equation for dist in TOF
d=t x square root of 2Ke
——-
m
