Bonding and Physical properties

type of crystal structure shown by silicon dioxide

Giant covalent structure

Write an equation when silicon dioxide reacts with Hydrofluoric acid to produce hexafluoro silicic acid

SiO2 + 6HF —> H2SiF6 + 2H2O

Nitrous acid decomposes on heating

3HNO2 —> HNO3 + 2NO + H2O

Sodium azide has a high melting point. Suggest why its melting point is high 

Ionic 

Strong electrostatic forces of attraction between oppositely charged ions 

requires a lot of energy needed to overcome strong attractions 

Give the general formula of the homologous series of straight chain bromoalkanes that contains one bromine atom per molecule

CnH2n+1X

CnH2n+1Br

Suggest one reason why (1-bromohexane) has a higher boiling point than (Z)

Stronger/ more vDW forces in between molecules of (1-bromohexane)

Explain why nickel has a high melting point, in terms of its structure and bonding

contains positive metal ions and delocalised electrons, strong electrostatic forces of attraction between molecules  

strong attraction between between strong metallic bonds 

Explain why nickel is ductile (can be stretched into wires)

sheets/ layers of atoms/ ions can slide over one another

full electronic configuration of the Ni 2+ ion

1s2 2s2 2p6 3s2 3p6 3d8 4s0

Suggest the type of bonding present in thallium (I) bromide and state why the m.p is high

Ionic bonding

with oppositely charged ions

strong attraction between ions

Write an equation to show the formation of thallium (I) bromide from its elements

Tl + ½ Br2 —> TlBr