periodicity
atomic radius decreases as you go across a period (period 3)
More protons so they pull the atom closer together
Attraction is stronger
Nuclear charge increases - more protons
Outer electrons are in the same shell
Same shielding
atomic radius increases down groups
extra electron shells were added for each element down the group.
melting points (period 3)
generally increases → metal ions have an increasing positive charge,
increasing number of delocalised electrons and smaller atomic radius →
stronger metallic bond
The First 3 elements in period 3 (Na, Mg, Al) have metallic bonding
Silicon has the highest melting point in p3 → it has a giant covalent
(macromolecular) structure → many strong covalent bonds hold the silicon
atoms together → a large amount of energy is needed to overcome these
strong covalent bonds.
dips in ionisation energy
The first dip between Mg and Al because the outer electrons of Mg are in the 3s
orbital whereas Al's outer electron is in the 3p orbital. The 3p electron has more
energy than the 3s electron, so the ionisation energy of Al is less Mg → s orbital
is closer to the nucleus.
In sulfur, the 4 electrons in the 3p level, are all paired. While in phosphorus,
there are 2 paired electrons and one lone electron in the 3p orbital. 1st
ionisation energy for sulfur will be slightly lower than that of phosphorus, due to
the paired electrons in its 3p sub-level.
periodicity 1
atomic radius decreases as you go across a period (period 3)
More protons so they pull the atom closer together
Attraction is stronger
Nuclear charge increases - more protons
Outer electrons are in the same shell
Same shielding
atomic radius increases down groups
extra electron shells were added for each element down the group.
melting points (period 3)
generally increases → metal ions have an increasing positive charge,
increasing number of delocalised electrons and smaller atomic radius →
stronger metallic bond
The First 3 elements in period 3 (Na, Mg, Al) have metallic bonding
Silicon has the highest melting point in p3 → it has a giant covalent
(macromolecular) structure → many strong covalent bonds hold the silicon
atoms together → a large amount of energy is needed to overcome these
strong covalent bonds.
dips in ionisation energy
The first dip between Mg and Al because the outer electrons of Mg are in the 3s
orbital whereas Al's outer electron is in the 3p orbital. The 3p electron has more
energy than the 3s electron, so the ionisation energy of Al is less Mg → s orbital
is closer to the nucleus.
In sulfur, the 4 electrons in the 3p level, are all paired. While in phosphorus,
there are 2 paired electrons and one lone electron in the 3p orbital. 1st
ionisation energy for sulfur will be slightly lower than that of phosphorus, due to
the paired electrons in its 3p sub-level.
periodicity 1
