The atom and redox Flashcards
relative isotopic mass
mass of an isotope compared to 1/12 of the mass of carbon-12
relative atomic mass
weighted mean mass of an atom compared to 1/13 of the mass of carbon-12
first ionisation energy
the energy required to remove one mile of electrons from one mile of gaseous atoms
how to calculate relative atomic mass
(% × mass) + (% × mass)
———-
100
How to calculate relative formula/molecular mass
add the Ar values together
Ionisation energy trend down a group
ionisation energy decreases when you go down a group:
* sheilding increases as you go down
Ionisation energy trend across period 2 and 3
Ionisation energy increases:
*nuclear charge increases
Why is the second ionisation energy always larger than the first?
The whole atom has an overall positive charge it’s harder to remove an electron from a positive atom
and electrons are pulled closer to the nucleus as an electron is removed so distance decreases = more nuclear attraction
What happens to ionisation energy as you start a new shell e.g between Mg 2nd and 3rd ionisation energy?
Ionisation energy increases massively as the new shell has less shielding, and a smaller radius between the outer electron and nucleus, so nuclear attraction increases.
Why can there be small decreases in ionisation energy across a period?
s and p sub shell energies e.g between Be and B, a new sub shell started so more shielding and further distance between outer electron and nucleus.
p-orbital repulsion e.g between N and O, N has a half filled P orbital, which is more stable, when O loses its electron it gains a half full so becomes more stable so will lose that outer electron easier.
How many electrons can fill the first 4 shells?
2,8,18,32
Shape of s and p orbitals
an s orbital is a sphere
a p orbital is a dumbbell shape that can be along the x y or z axis.
order in which sub shells fill
1s 2s 2p 3s 3p 4s 3d 4p …
Why does the 3d orbital fill after the 4s?
The 4s orbital has a lower energy than 3d so is favoured to fill before the 3d orbital, however the electrons in 4s will be lost before those in 3d.
What is a degenerate orbital
orbitals of identical energy.
