2.3 Period 3 + their Oxides

Period 3 Basics

Period 3 Basics

What happens to the following across Period 3:

• Nuclear charge (aka. No of Protons)

• Number of Electrons

• Atomic radius (+why)

• Shielding

• Nuclear charge increases

• Number of electrons increase

• Atomic radius decreases: Since ESF of attraction increases due to more electrons and protons 

• Shielding is constant

What are the classes, types of structures + bonding in the Period 3 elements? (Na → Ar)

• Na, Mg, Al = Metals → Metallic lattice → Metallic bonding

• Si = Metalloid → Giant covalent lattice → Covalent bonding

• P, S, Cl = Non-Metals → Simple molecule structure → Simple Covalent bonding

• Ar → Unreactive gas

What is the trend in Mp across the Period 3 metals? (2 reasons why)

Na<Mg<Al:

• As their ion charge increases by one (+1), they delocalise more electrons as you go across period 3, resulting in stronger ESF requiring more energy to melt + break bonds

• Radius decreases + charge increasing, increasing their charge density across the period

What type of molecules do Silicon atoms form (why)

• What other element can do this?

• Macromolecules = Si can bond to any number of Si atoms to form macromolecules

• Carbon can also do this

How many bonds can the following elements make to their atoms to form their molecules: (i.e oxygen = 2 bonded O atoms = O₂)

• Phosphorus

• Sulfur

• Chlorine

• P = 4 bonded P atoms → P₄

• S = 8 bonded S atoms → S₈

• Cl = 2 bonded Cl atoms → Cl₂

What is the Mp “status” of Silicon (why)

Highest Mp of all P3 elements:

• Strong covalent bonds hold the many Silicon atoms that form its macromolecules, requiring large amounts of energy to break the giant covalent lattice

What do the Non-Metals of Period 3 Mp rely on?

VDW

What is the trend in Mp across the Period 3 Non-Metals? (2 reasons why)

Cl < P < S:

• Molecules of Cl₂ have the fewest electrons then P₄ and S₈ with the most

• Molecule size also affected by the number of atoms bonded (same reason as above)

• Both of these reasons result in greater VDW forces for Sulfur compared to Phosphorus then Chlorine

What is the Mp of Argon compared to other P3 elements? (why)

Lowest - Since its monatomic and has fewer types of bonds to increase the energy needed to break its structure and melt it

***All chemical reactions are in IRL FC***

***All chemical reactions are in IRL FC***