module 2 - electrons, bonding and structure Flashcards
how do you represent shell number at a-level?
n = 1 n = 2 n = 3 n = 4
how many electrons are in the 1st shell?
2
how many electrons are in the 2nd shell?
8
how many electrons are in the 3rd shell?
18
how many electrons are in the 4th shell?
32
what are shells also known as?
energy levels
what increases as shell number increases?
the energy increases
what is the shell/energy level number called?
the principal quantum number n.
what formula tells you the maximum number of electrons in a shell?
2n^2
what are shells made up of?
atomic orbitals
what’s an atomic orbital?
A region around the nucleus that can hold 2 electrons with opposite spins
what shape is an s-orbital?
spherical
what happens to the s-orbital with greater shell number?
the radius of its s-orbital is bigger
in a p-orbital, what is the electron cloud within?
the shape of a dumb-bell
how are p-orbitals positioned?
at right angles to each other
How many p-orbitals does each shell form n=2 contain?
3
what happens to the p-orbital with greater shell number?
the further it is from the nucleus
how many d-orbitals does each shell from n=3 contain?
5
how many f-orbitals does each shell from n=4 contain?
7
what’s a sub-shell?
a group of orbitals of the same type within a shell
why does the 4s sub-shell fill before the 3d sub-shell? what comes after it?
- because it’s at a lower energy level than the 3d sub-shell
- it goes: 3p, 4s, 3d, 4p etc…
what property do electrons have? in which direction?
- spin
- up or down
what must 2 electrons in an orbital have? why?
- opposite spins
- to counteract the repulsion between the negative charges of the 2 electrons
within a sub-shell what is similar for all the orbitals?
they have the same energy
when orbitals are filled up, what is the rule? why?
- 1 electron occupies each orbital before pairing up
- this prevents any repulsion between paired electrons
what does the electron configuration of an atom show?
How sub-shells are occupied by electrons
in 1s^2 which is the electron and which is the sub-shell?
- s = sub-shell
- 2 = electron
what is the shorthand notation for lithium’s electron configuration
[He] 2s^1
what do the blocks in the periodic table correspond to?
to their highest energy subshell
when forming ions, which sub-shells lose or gain electron?
the highest energy ones
why does the 4s sub-shell empty before the 3d when forming ions?
because once filled, the 3d energy level falls below the 4s energy level
