ATOMIC STRUCTURE/AOS Flashcards
What was Niels Bohr’s model & discovery?
Model: where electrons exist in shells or orbits of fixed energy
Discovered: When electrons move between shells, electromagnetic radiation (with fixed energy or frequency) is emitted/absorbed
protons charge and mass
mass: 1
charge: +1
Neutrons charge and mass
mass: 1
Charge: 0
Electrons charge and mass
charge: -1
Mass: 1/1840
Iosotopes
same No of protons
Different No of neutrons
same e- configuration
1st ionisation energy
ENTHALPY CHANGE WHEN ONE MOLE OF e- IS REMOVED FROM ONE MOLE OF GASEOUS ATOMS TO FORM ONE MOLE OF GASEOUS 1+ IONS
trend in ionisation energy along a period?
ionisation energy increases
why does ionisation energy increases along a period?
atomic radius decreases
increases in charge
outer e- is strongly attracted to nucleus so requires so more energy required to remove outer e-
trend in ionisation energy down a period?
ionisation energy decreases
why does ionisation energy decreases down a period?
attraction between nucleus and outer e- decreases
more shielding
less energy required to remove outer e-
Trend in ionisation energy across P2? (6 marker)
STAGE 1
General increase in IE
same shielding as same number of shells
greater attraction between nucleus and outer e-
STAGE 2
B lower than Be
outer e- in 2P
higher in energy than 2S
STAGE 3
O lower than N
2 e- in 2P needed to be pair
e- pair repulsion
Define Ar
Mean mass of an atom of an element /one twelfth of the mean mass of an atom of the carbon 12
Define Mr
mean mass of a molecule of a compound/ 1 twelfth of the mean mass of ab atom of the carbon 12
Calculate:
No of particles
moles x 6.022x10^23
calculate moles
(2 equations)
Mass/ Mr
Con x Vol
percentage yield
experimental mass 100 / theoretical mass
atom economy
Mr of desired product 100/ Mr of reactants
empirical formula steps
simplest whole number ratio
1. mass/ %
2. / Ar
3. / smallest value
4. ratio
steps to make up a standard solution (6marks)
- weigh sample containing solid on a balance
- transfer to beaker and reweigh sample bottle
- record difference in mass
- add distilled water
- still until solid dissolve
- transfer to volumetric flask using a funnel
7 with washing
8 make up to 250cm3
9 mix
Bohe model 3 mark points
Protons and neutrons are found in the center of the atom called nucleous
Protons and neutrons can also be called nucleons
Electrons saurround the nucleous in shells
What in atomic number (Z)
Number of protons
What is mass number (A)
Protons + neutrons
What is cations and anions
Cations- lost electrons ( +ve charge)
Anions- gained electrons ( -ve charge)
Write the first and second ionisation evergy for X
1st: X(g) ——> X+(g) + e-
2nd: X+(g) ——> X2+(g) + e-
What 3 factors influence ionisation energy
Nuclear charge
Shielding
Distance from nucleus
Electron impact
sample vaporaised
High electrons are fired at samo,e by electron gun
Ehich knicks off one electron
Equation of electron impact
X(g) ——> X+(g) +e-
Electrospray ionisation
Sample dissolved in a volatile solvent and injected through a hypodermic needle which is attached to the positive terminal of a high-volatge power supply
Particles ionised by gaining a proton
Equation of electrospray ionisation
X(g) + H+ ——> XH+(g)
Why are sample particles ionised in mass spectometry
Can be accelerated towards negatively charged plate
So they generate a current then they hit the detector
How is the ion accelerated in mass spectometry
+ve ions attracted to negatively charged plate
All ions have same Ke
How are ions separated in the flight tube?
Ions travelling at higher soeeds (small m/z) move ahead of those travelling more slowly
How are ions detected
Each ions hit detector
Ions gains an electron
Generates a current
Size of current is proportional to the abundance of the ion
Why is mass spectometry in a vacuum
No Particles being tested colliding with molecules from the air
How are ions detected and how is there ambumcane sample
Positive ions ganis electron when they arrive to the detector
Generates a current which is proportional to the number of each type of ion
