Atomic structure & Amount of substance Flashcards
What are the quantum numbers?
The principal quantum numbers are the so-called shells of electrons.
Define orbitals (I came up with a sort-off definition so don’t worry if you don’t know how to define them, you most likely understand them anyway)
Orbitals are sort of a ‘flat’ electrons have that can fit up to two, oppositely spinning electrons.
s contains 1 orbital;
p contains 3 orbitals;
d contains 5 orbitals;
f contains 7 orbitals.
S-Orbitals! Describe them :)
S-orbitals have a form of a sphere and there is a 95% chance to find an electron in there.
Describe P-Orbitals
P-orbitals have a shape of a dumbbell and appear in groups of three - Px, Py and Pz, these represent the axes these orbitals lay on.
Electrons move very quickly in these orbitals, creating areas of electron density as they can be anywhere in that space at any time.
Why don’t the electrons ever go in between the energy levels? Why are the levels discrete? (knowing Alan just in case)
Energy can only absorbed or released in single quantums, small ‘packets’ of energy. These quanta do not occur in part and so all energy interactions in the universe have discrete values.
What is the Pauli’s Exclusion Principle (also the 1st rule of Electronic configuration)
The electrons must have different spins.
What is The Aufbau process? (also the 2nd rule of Electronic configuration)
The electrons fill up the lowest energy levels.
What is the Hund’s rule? (also the 3rd rule of Electronic configuration)
We half fill the orbitals of the same energy with electrons of the same spin.
Electronic configuration for ions?
When doing electronic configuration for an ion please remember to consider lost/gained electrons it has.
Electronic configuration for Cu and Cr?
Cu - 1s2 2s2 2p6 3s2 3p6 4s1 3d10 NOT 4s2 3d9
Cr - 1s2 2s2 2p6 3s2 3p6 4s1 3d5 NOT 4s2 3d4
What is Ionisation energy?
Ionisation energy is an energy required to remove 1 mole electrons from 1 mole of gaseous atom or ion.
First and second Ionisation energy formula(use X as an element)
1)X —> X+ + e-
2)X+ —> X2+ + e-
What affects Ionisation energy?
- Distance from the nucleus, further from the nucleus - less energy needed to remove an electron since the attraction is weaker;
- Nuclear attraction, higher attraction(more protons) - more energy needed to remove an electron;
- Shielding, more shells - less energy needed to remove an electron since the attraction is weaker.
General trends in Periodic table?
Down a group:
- More nuclear attraction;
- Greater distance from the nucleus;
- Greater shielding.
Ionisation energy decreases.
Across the period:
- More nuclear attraction;
- Same distance;
- Same shielding.
Ionisation energy increases.
How do we determine what group an unknown element is using a table with ionisation energy?
Huge energy ‘jumps’, since removing an outer shell electrons are easier than from a lower energy level.
In example, when removing Na electrons there is a huge gap between First and Second Ionisation energies. Now looking at Na electronic configuration- 1s2 2s2 2p6 3s1, we can see that the Second Ionisation energy is trying to remove an electron from 2p orbitals and that requires much more energy than removing 3s one since we moved down a shell if that makes sense.
What are the two exceptions in a general Ionisation energy table trend?
Group II to Group III
Group V to Group VI
Why these exceptions occur?
Group II to Group lll:
It is much easier to remove an electron from the p-subshell despite greater nuclear attraction, because 3s subshell is shielding this p-electron and makes it easier to remove since the attraction gets weaker.
Group V to Group VI
It is due to electron repulsion that happens once you double fill the p-orbital, the repulsion is enough to make it easier to remove.
What is Mass Spectrometry?
It is a method that is used to measure mass-to-charge ratio in one or more molecules present in a sample. This method is also used to calculate the exact molecular mass of the sample components as well.
Mass spectrometry stages?
Vaporization - (Substance is vaporized so that particles moved freely) ->
Ionisation(Electrons are “kicked out” to create a positively charged ion) -> Acceleration(Ions are accelerated so they have the same kinetic energy) -> Detection(Ions are than electrically detected by the machine and can be sorted by masses)
What are the three sub-atomic particles?
- Protons;
- Neutrons;
- Electrons.
Relative masses and charges of sub-atomic particles?
Protons - 1 amu - +1
Neutrons - 1amu - 0
Electrons - 0.00055(we don’t take them into account because how light they are) - -1
Location of sub-atomic particles?
Protons and neutrons are found in the nucleus while electrons are found around it. Therefore the nucleus is positively charged but this charge is cancelled out by electrons.
What is an Isotope?
An atom of the same element with the same amount of protons but different amount of neutrons.
Name three Hydrogen Isotopes(for fun)
- Protium;
- Deuterium;
- Tritium.
Ideal gas equation
pV = nRT
p - pressure in Pa
V - volume in dm3
n - moles
R - gas constant - 8.314 J K-1 mol-1
T - temperature in Kelvin (°C + 273)
What is an ideal gas?
An ideal gas is the gas we think about when we consider the kinetic model
- Molecules have zero volume
- zero intermolecular forces
- constant random motion
- elastic collisions (without loosing energy)
Real gases do not behave quite that way.
Rearranged the ideal gas equation for Mr
Mr = mRT/pV
Avogadro constant?
6.02*10^23 per mole
What’s an empirical formula?
Unlike Molecular formula it doesn’t give you the actual number of atoms in a molecule but gives you the ratio.
Four steps when calculating empirical formula?
- Convert % to grams;
- Calculate the moles;
- Divide the results by the smallest;
- Find the whole number ratio.
“Standard” Gas Volume?(I really don’t know what you call it)
1 mol of gas has a Volume of 24 dm3 at room temperature and pressure
Under standard conditions it is 22.4 dm3
What is a percentage yield formula?
What you got/what you should have got
What’s atom economy formula?
(Mr of desired product/sum of Mr of all reactants)*100%
