Atomic orbitals, electron configuration and the periodic table Flashcards
What is an orbital?
An orbital is an area of space where there is >90% chance of finding an electron.
What do quantum numbers tell us?
Where to find an electron in an orbital
What are the four steps of quantum numbers?
- Principle quantum numbers
2.angular momentum quantum numbers
3.magnetic quantum numbers
4.spin quantum numbers
What are principle quantum numbers? (n)
Essentially how far away from the nucleus it is,
n=1 is the 1st shell
n=2 is the 2nd shell
n=3 is the 3rd shell etc
the further away from the nucleus the higher the value of n
What are angular momentum quantum numbers? (l)
Essentially the shape
- each shell has up to 4 subshells
S block- l=0
P block l=1
D block l=2
F block l=3
What is Heisenberg’s uncertainty principle?
It is not possible to define both the position and the momentum of an electron in the same instant.
What does the shape of an s orbital look like ( l=0 )
all s orbitals are spherical in shape and the size depends on the value of n - you should be able to recognise these and draw them
what does the shape of a p orbital look like ( l=1 )
They are not spherical in shape and look like infinity signs
all 3 p-orbitals are equal in energy
you should be able to recognise and draw these
What does a d orbital look like
they are not spherical, usually consists of shapes that look like 2 infinity signs together.
all 5 d orbitals are normally degenerate
What does degenerate mean?
Equal in energy
What are magnetic quantum numbers?
Magnetic quantum numbers distinguish between the different suborbital within the Sprint,d and f subshells
magnetic quantum numbers have the values -l,…, 0,…, +l
What are spin quantum numbers?
electrons have a spin rotation in additions top orbital rotation around the nucleus
Can either be +1/2 or -1/2
What is the layout for writing quantum numbers?
( n, l, ml, ms )
n= energy level
l= shape
ml= type of suborbital
ms= spin +1/2 or -1/2
What is the Pauli Exclusion Principle?
- no two electrons have the same 4 quantum numbers
-an orbital can hold a maximum of 2 electrons
What is the Aufbau principle?
orbitals with the lowest energy fill up first, the lowest energy orbitals are not always necessarily closest to the nucleus.
In what order to orbitals fill up? (written out diagram)
Starting from the lowest energy orbitals
1s, 2s, 1p, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s
what is Hund’s rule?
Where electrons occupy degenerate orbitals, each electron will take a separate orbital until all the orbitals in that sub shell are half-filled.
( electrons fill in order to maximise the number of parallel spins - electrons do not pair until they have too. )
How many electrons are in each orbital (s,p,d)
s=2
p=6
d=10
How do you write box notation?
Draw one arrow pointing up wards and one pointing downwards for each electron on each orbital, do not pair the electrons in the orbital until you haver too.
What is ionisation energy ( higher definition )
The energy required to remove one mole of electrons from one mole of atoms in the gaseous state
What is the relationship between stability of electron configuration and ionisation energy.
The more stable the electron configuration, the higher the ionisation energy.
Why is the second ionisation energy a lot greater then the first?
Because the second ionisation energy requires removing an electron from a shell closer to the nucleus, so there is a greater force of nuclear attraction ion acting on this shell as it is closer to the nucleus.
What are 3 factors affecting ionisation energy?
Atomic size, Nuclear charge, Screening effect
How does atomic size affect ionisation energy?
The greater the atomic radius of the atom, the further the distance of the outermost electrons , this lowers the ionisation energy as the electrons are less attracted to the nucleus the further away they are.
How does nuclear charge affect ionisation energy?
The greater the number of protons the greater the attraction to the outer electrons and harder it is to remove electrons.
elements across a period have decreasing atomic size and increasing number of protons in the nucleus therefore increasing ionisation energy.
How doe the screening effect affect the ionisation energy?
Inner electron shells shield the outer electron shells from the attractive forces from the nucleus.
this makes the outer electrons easier to remove so the ionisation energy decreases.
Why does Beryllium have a higher 1st ionisation energy than the trend would expect.
electron configuration of Be - 1s^2 , 2s^2
removing an electron from Be will break a full subshell, this requires more energy so it increases the ionisation energy.
Why Is the first ionisation energy of Boron a lot lower than expected?
Electron configuration of B - 1s^2, 2s^2, 2p^1
removing an electron from B empties the 2p sub shell and makes the 2s^2 sub shell the outer shell.
Creating a full outer shell is favoured and this is why the IE of B is a lot lower.
Why does Nitrogen have a higher 1st ionisation energy than expected?
Electron configuration of N - 1s^2, 2s^2, 2p^3
removing an electron from N breaks a relatively stable half filled 2p sub shell, breaking half filled subshells requires more energy which is why the IE is higher.
Why does Oxygen have lower 1st ionisation energy than expected?
Electron configuration of O - 1s^2, 2s^2, 2p^4
removing an electron from O creates a half-filled 2p sub shell which is more stable.
Creating a half-filled sub shell is favoured and this is why the ionisation energy is a lot lower.
