Trends across period 3

Question	Answer
Trends in melting and boiling point across period 3	The genral trend is that the melting and boiling points increases and then decrease as you move across period 3
Na to Mg to Al	The melting points increase from Na to Mg to Al becuase the strength of the metallic bonding increases. Na only forms +1 ions, Mg +2 ions and Al +3 ions, also Na is the largest ion and Al is the smallest, so Na has the weakest force between the ions and delocalised electrons.
Si	Silicon has the highest melting point as it has a gaint macromolecular structure held together by strong covalent bonds. these require a lot of energy to break apart thus Si has a high melting point.
P to S to Cl	P exists as P4 tetrahedrons, S exists as S8 rings and Cl as Cl2. the melting point of these elements depends on the van der waals force between the molecule. S8 is big rings so it has the strongest Van der waals and Cl is diatomic so it has the weakest Van der waals.
Ar	Argon exists as a single atom thus it only has weak Van der waals resulting in the lowest boiling point.

Resource summary

	Created by Irene Binil over 6 years ago