Period 3

Across the Period 3 , the elements are

• Na Mg Al C S P Cl Ar

• Na Mg Al Si P S Cl Ar

• Li Be C N O He

• Li Be Si S P Cl Ar

Going across the Period 3 of the Periodic Table from Sodium to Chlorine ,

• The number of filled electronic shell increases

• The atomic mass increases

• Electrical conductivity increase

• The electrode potential become more negative

Which oxide of an element dissolves in water to form acidic solution

• Sodium

• Magnesium

• Silicon

• Phosphorus

Across the period 3 , atomic radii of elements decrease due to

• proton number increase

• screening effect increase

• nucleus attraction increase

• the number of shell filled with electron increase

Sulphur has higher melting point than phosphorus . It is due to

• Van der Waals forces is stronger

• size is smaller

• Sulphur exit as S₈

• higher charge density

Which pair is correct ?

• Magnesium Simple Molecular Structure

• Silicon Metallic Bonding

• Phosphorus Giant Covalent Structure

• Argon Monoatom

Silicon has highest melting point. Which statement is incorrect about its melting point.

• Silicon is a metalloid

• The structure is held by a strong covalent bond

• Silicon need more energy to break the strong covalent bond

• Silicon has a giant covalent structure

Which statement is incorrect explain the metallic structure?

• Number of electrons which each atom can contribute to the delocalised "sea of electrons" increases

• The "sea of electrons" is getting progressively nearer to the nuclei and so more strongly attracted.

• Greater screening effect due to an extra shell of electrons.

• Number of electrons which each atom can contribute to the delocalised "sea of electrons" increases

∆H vapor of an element is the enthalpy heat change when 1 mol of an element is converted from liquid to vapour as its boiling point.

Which element has the highest ∆H in Period 3 ?

• Na

• Mg

• Si

• P

Which element in Period 3 has the highest electrical conductivity ?

• Na

• Mg

• Al

• Si