FC7 Flashcards
How to explain trends in atomic radius and 1st IE
1) Describe change in nuclear charge and total number of e’s
2) describe the number of shells
3) Describe the shielding
4) Describe the atomic radius
Define atomic radius
The average distance between the nucleus and the outermost e’s in an atom
Define nuclear charge
The charge of the nucleus due to the number of protons
Define the electron shielding/shielding effect
Is caused by the mural repulsion between the inner shells e’s and the outer shell e’s. This reduces the attraction between nucleus and outer e’s.
Define 1st Ionisation Energy
The energy needed to remove one mole of e’s from one mole of gaseous atoms to form one mole of gaseous uni positive ions
X —> X+ + e’
Why has Boron got a lower ionisation energy that Be and C
The e’ being removed from Boron is from a 2p sub shell, which is at higher energy ( further from the nucleus ) than the e’ being removed from a 2s sub shell for Be.
Why has Oxygen got a lower ionisation energy than N and F
The e’ being removed from O is a paired electron which experiences mutual repulsion therefore it requires less energy to remove than the unpaired e’ from N
Define successive ionisation energies
These are the energies needed to remove each e’ from an atom in succession.
Why does the successive IE increase
The remaining e’ can crowd closer to the nucleus after each ionisation. This is because there is less mutual repulsion between the remaining e’. So the ionic radius decreases and the attraction between the nucleus and e’ being removed increases.
