Physical properties of period 3 elements Flashcards
What is the trend of Atomic Radius across a period?
AR decreases across the period
Why does the atomic radius increase across the period?
The size of the atom increases because there are more protons
Nuclear charge increasing causes more attraction between shells towards the nucleus
What is the trend of 1st ionisation energy across a period?
General increase
Why does the 1st IE generally increase across the period
Nuclear charge increasing causes more electrostatic attraction between nucleus and electrons
In which 2 places does the IE decrease?
From Mg to Al
From P to S
Why does IE decrease from P to S?
In P, the electrons are individual in the p subshell, however in S there is one pair, so there is repulsion
This means less energy is required to remove the outer electron
Why does IE decrease from Mg to Al?
There is a minor increase in shielding as the new p orbital is filled up
What is the bonding of Na, Mg, Al?
Metallic bonds
What is the bonding of Si?
forms a giant covalent lattice
What is the bonding of Ar?
Very rarely forms bonds
What is the bonding of S, P and Cl?
Forms covalent bonds
What is the trend of melting point across the period?
This depends on the structure and bonding
Explain the increasing melting point of P3 metals
Mg is larger than Na, so it has more electrostatic attraction, and stronger metallic bonding as the nuclear charge increases
Explain the melting point of Si
Si can covalently bond with any number of other Si atoms, these form large structures called macromolecules
This has an extremely high melting point (HIGHEST)
Explain the melting point of P, S, Cl & Ar
S forms S8 - 1
P forms P4 - 2
Cl forms Cl2 - 3
Ar - 4
Larger molecules have more VDW and therefore higher mp
