2.2: How bonding and structure are related to the properties of substances

Question 1

What are the three states of matter?

Answer 1

Solid, liquid, gas.

Question 2

Where do the following processes take place: melting, freezing, boiling and condensing.

Answer 2

● Melting​ ​and​ ​freezing​ ​take​ ​place​ ​at​ ​the​ ​melting​ ​point
● Boiling​ ​and​ ​condensing​ ​take​ ​place​ ​at​ ​the​ ​boiling​ ​point

Question 3

Describe the limitations of the particle model.

Answer 3

In​ ​the​ ​model​ ​there​ ​are​ ​no forces;​​ ​all​ ​particles​ ​are​ ​represented​ ​as​ ​spheres​; ​and​ ​that​ ​the​ ​spheres​ ​are solid.

Question 4

What are the properties of ionic compounds? (1)

Answer 4

● Ionic​ ​compounds​ ​have​ ​regular​ ​structures​ ​(giant​ ​ionic​ ​lattices)​ ​in​ ​which​ ​there​ ​are strong​ ​electrostatic​ ​forces​ ​of​ ​attraction​ ​in​ ​all​ ​directions​ ​between​ ​oppositely
charged​ ​ions.

Question 5

What are the properties of ionic compounds? (2)

Answer 5

● They​ ​have​ ​high​ ​melting​ ​and​ ​boiling​ ​points,​ ​because​ ​a​ ​lot​ ​of​ ​energy​ ​is​ ​required​ ​to break​ ​the​ ​many​ ​strong​ ​bonds.
● When​ ​melted​ ​or​ ​dissolved​ ​in​ ​water,​ ​ionic​ ​compounds​ ​conduct​ ​electricity​ ​because the​ ​ions​ ​are​ ​free​ ​to​ ​move​ ​and​ ​carry​ ​current.​ ​But​ ​they​ ​can’t​ ​conduct​ ​electricity when​ ​solid​ ​because​ ​the​ ​ions​ ​are​ ​fixed​ ​in​ ​place.

Question 6

What are the properties of small molecules?

Answer 6

● Substances​ ​that​ ​consist​ ​of​ ​small​ ​molecules​ ​are​ ​usually​ ​gases​ ​or​ ​liquids​ ​that​ ​have low​ ​boiling​ ​and​ ​melting​ ​points, and weak intermolecular forces
● Substances​ ​that​ ​consist​ ​of​ ​small​ ​molecules​ ​don’t​ ​conduct​ ​electricity,​ ​because small​ ​molecules​ ​do​ ​not​ ​have​ ​an​ ​overall​ ​electric​ ​charge.

Question 7

Describe polymers:

Answer 7

● Have​ ​very​ ​large​ ​molecules
● Atoms​ ​in​ ​the​ ​polymer​ ​molecules​ ​are​ ​linked​ ​to​ ​other​ ​atoms​ ​by​ ​strong​ ​covalent bonds
● Intermolecular​ ​forces​ ​between​ ​polymer​ ​molecules​ ​are​ ​relatively​ ​strong​ ​and​ ​so these​ ​substances​ ​are​ ​solids​ ​at​ ​room​ ​temperature

Question 8

What are the properties of giant covalent structures?

Answer 8

● Substances​ ​that​ ​consist​ ​of​ ​giant​ ​covalent​ ​structures​ ​are​ ​solids​ ​with​ ​very​ ​high melting​ ​points.
o All​ ​of​ ​the​ ​atoms​ ​in​ ​these​ ​structures​ ​are​ ​linked​ ​to​ ​other​ ​atoms​ ​by​ ​strong covalent​ ​bonds.

Question 9

What is an alloy?

Answer 9

Alloys​ ​are​ ​made​ ​from​ ​2​ ​or​ ​more​ ​different​ ​types​ ​of​ ​metals. Alloys​ ​are​ ​harder​ ​than​ ​pure metals.

Question 10

Why are metals good conductors?

Answer 10

They are good​ ​conductors​ ​of​ ​electricity​ ​because​ ​the​ ​delocalised​ ​electrons​ ​in​ ​the​ ​metal carry​ ​electrical​ ​charge​ ​through​ ​the​ ​metal.