Summary
Summary Chemistry Unit 2 Booklet
- Institution
- PEARSON (PEARSON)
A booklet of detailed and helpful notes for chemistry unit 2, including written questions that have been left blank to help test your knowledge.
[Show more]
Seller
Follow
Content preview
A-Level ChemistryTopic 2
Bonding and Structure
Name: ___________________________
Form: ___________
Teacher:________________________
1
, Topic 2: Bonding and Structure - Specification
PART 1: FUNDAMENTALS OF BONDING AND STRUCTURE
Part 1(a): Ionic Bonding
Part 1(b): Metallic Bonding
Part 1(c): Covalent Bonding
Part 1(d): Electronegativity
2
,And in General (Covering Parts 1(a),(b),(c)
PART 2: SHAPES OF MOLECULES
PART 3: INTERMOLECULAR FORCES
3
, PART 1: FUNDAMENTALS OF BONDING AND STRUCTURE
Part 1(a): Ionic Bonding
Ionic bonding is the strong electrostatic attraction between oppositely charged ions.
Formation of ions: Dot and Cross diagram revision
E.g. sodium chloride E.g. magnesium fluoride
Chemistry HELP-SHEET 12
LATTICE ENTHALPY (ENERGY)
WARNING
There are two definitions - one is the opposite of the other!
Make sure you know which one is being used.
Lattice Dissociation Enthalpy
Definition The enthalpy change when ONE MOLE of an ionic lattice dissociates into isolated gaseous ions.
Values • highly endothermic - strong electrostatic attraction between ions of opposite charge
What determines the strength of anmust
• a lot of energy ionicbebond
put in and hence the
to overcome an attraction
ionic structure?
• relative values are governed by the charge density of the ions.
The strength of an ionic bond is related to its lattice energy. The more exothermic the lattice energy, the stronger
the ionic Example
bonds. Na+ Cl¯(s) -———> Na +(g) + Cl¯(g)
Lattice Energy facts (also see Topic 8 (Born Haber cycles))
Lattice Formation Enthalpy
Definition The enthalpy change when ONE MOLE of an ionic lattice is formed from its isolated gaseous ions.
Values • highly exothermic - strong electrostatic attraction between ions of opposite charge
• a lot of energy is released as the bond is formed
• relative values are governed by the charge density of the ions.
Example Na+(g) + Cl¯(g) -———> Na + Cl¯(s)
Notes • one cannot measure this value directly ; it is CALCULATED USING A BORN-HABER CYCLE
• the greater the charge densities of the ions, the more they attract each other and the
larger the lattice enthalpy.
• the higher the lattice enthalpy, the higher the melting point of the compound
• solubility of ionic compounds is affected by the relative values of Lattice and Hydration Enthalpies
Theoretically, lattice energy is proportional to
Some Lattice Enthalpy Values
Cl¯ Br¯ F¯ O2-
Check which definition Na+ -780 -742 -918 -2478
is being used and use K+ -711 -679 -817 -2232
appropriate sign for DH Rb+ -685 -656 -783
Mg2+ -2256 -3791
Ca2+ -2259
4
Smaller ions will have a greater attraction for each other because of their higher charge density. They will
have larger Lattice Enthalpies and larger melting points because of the extra energy which must be put in to
separate the oppositely charged ions.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller jasonsenoo. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £3.00. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
62555 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now