Unit 2 Bonding and its properties (new spec)

if any of you need some revision notes, heres some i made from the aqa textbook so i hope it helps and this is the new 2015 spec

HideShow resource information
  • Created by: saadaelmi
  • Created on: 27-11-16 12:15
Preview of Unit 2 Bonding and its properties (new spec)

First 362 words of the document:

Bonding and physical properties
turning a solid to liquid (fusion)
When heating, a solid or supplying energy,
it vibrates to a more fixed position
therefore increasing the distance between
particles so it expands
Supplying more energy can turn a solid
into a liquid ­ this is required to weaken
the forces that act between the particles
- Energy known as the enthalpy change
of melting
When a solid is melting, the temperature
does not change as the heat is absorbed as
the forces are weakened
Enthalpy = the heat energy change measured
under constant pressure
Temperature depends on the average kinetic
energy which is also related to their speed
Turning a liquid to a gas (vaporisation)
Particles move further apart after being supplied energy therefore liquids also expand when heated
Energy is required to break all the intermolecular forces between the particles
- Energy known as enthalpy change of vaporisation
No temperature change during the process of boiling
Gases expand a great deal when heated because they also gain kinetic energy and move further apart
Crystals
Have a regular arrangement and are held together by forces of attraction
The strength of forces of attraction has an effect on the physical properties of crystals
Stronger the force, the higher the melting point/temperature and a greater the enthalpy
Molecular crystals ­ consist of molecules held in a regular structure by intermolecular forces and molecules held
together by covalent bonds however are much weaker so have a low melting temperature and low enthalpy
Properties
Crystals are soft and break easily
Low melting point temperature
Does not conduct electricity because there are no charged particles
Diamond (macromolecular crystal)
Polymorph or allotrope of carbon
Consists of pure carbon with covalent bonding between every carbon atom
Giant structure ­ bond spreads throughout the structure
Each carbon forms four single covalent bonds with other carbon atoms
These four electrons repel from each other ­ electron pair repulsion theory
Bond angles of 109.5

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Properties of diamond
Very hard material
Very high melting temperature (over 3,700k)
Does not conduct electricity because there are no delocalised electrons to carry the charge
Graphite
Consists of pure carbon atoms which are bonded and arranged differently
Strong covalent and weak van der Waals forces
Bond at angle 120°
Leaves each carbon atom with a spare electron in a p-orbital that is not part of the three single covalent
bonds
Electrons are able to move anywhere within the layer (delocalised)
Weak intermolecular forces allows…read more

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »