How bonding and structure are related to the properties of substances

2.2.1  The three states of matter

Properties of Solids, Liquids and Gases

Solid	Liquid	Gas
Close together in regular pattern Strong intermolecular force of attraction Vibrate at fixed position Fixed shape & volume	Close together in random pattern Further apart than solid Weaker intermolecular force of attraction Slide past each other Can’t be compressed coz large intermolecular forces when molecules moved closer	Far apart in random pattern Weaker intermolecular force of attraction Move quickly in all directions Can flow or compress

State Changes

States of matter can be represented using a model called particle theory.

How are particles represented in this model? (1)

Small solid spheres

Explain the limitations of particle theory (2)

• Doesn’t show forces between particles
• Particles are not solid spheres
• Particle theory can be used to explain changes of state.
• Using particle theory, explain how a substance changes from a liquid to a gas when it is heated. (3)
• When a liquid is heated, particles gain KE & move faster
• Weakens bonds holding liquid tgt
• At certain temp, particles have sufficient energy to break bonds
• Liquid becomes gas
• 2.2.2  State symbols
  Solid (s), Liquid (l), Gas (g), Aqueous solution (aq)
• 2.2.3  Properties of ionic compounds

(See 2.1.2 Ionic bonding)

2.2.4  Properties of small molecules

(See 2.1.4  Covalent bonding)

2.2.5  Polymers

• Long chain molecule made from joining many short molecules (monomers) together
• Strong intermolecular force – hard to break – solid at room temp
• Different polymers, different properties, different uses

• Thermosoftening polymer	Thermosetting polymer
  Contain long polymer chains Chains are not joined tgt (but are tangled up with each other) Low melting point – soften and then melt when heated	Contain long polymer chains Chains are joined by covalent bonds High melting point – do not soften or melt when heated

• 2.2.6  Giant covalent structures

  (See 2.1.4  Covalent bonding)

  2.2.7  Properties of metals and alloys

  (See 2.1.5  Metallic bonding)

  2.2.8  Metals as conductors

  (See 2.1.5  Metallic bonding)