1. 12.2 – Structures Heolddu Comprehensive School 27/05/2016

2. Ionic Structures An ionic compound is a _____ structure of _____. Ionic compounds are held together by strong forces of _________ between oppositely charged ions. These forces act in all ________ in the _______ and this is called ionic bonding. Attraction giant directions ions lattice

3. 27/05/2016 Giant Ionic Structures (Ionic Lattices) Examples : –Sodium chloride (NaCl), Calcium chloride (CaCl 2 ). _____ melting and boiling points due to ______ electrostatic forces of attraction. Can conduct electricity when _______ or dissolved in water, because the _____ are free to move and carry the ________.

4. 27/05/2016 Giant Covalent Structures (Macromolecules) Many non-metal atoms sharing electrons. Examples: Diamond, Graphite, Silicon dioxide All atoms linked by _______covalent bonds, so ______ M.pts an B.pts. Diamond – Each carbon is bonded to 4 other carbon atoms –very hard. Graphite – carbon atoms bonded to 3 other carbons and arranged in layers, making graphite soft and slippery. – 1 free, delocalised _______ per carbon enables carbon to conduct _________ and heat.

5. 27/05/2016 Simple Covalent Molecules A few non-metal atoms covalently bonded. Examples: - Water, Carbon dioxide, Methane, Ammonia _____ M.Pts and B.Pts due to ______ intermolecular forces. It is these forces (not the covalent bonds) that are overcome when the substance melts or boils. Do not _________ _________ as there is no charge on the molecules.

6. 27/05/2016 Metallic structures Metals conduct ______ and ________ because of the _________ electrons in their structures. The layers of atoms in metals are able to slide over each other and so metals can be bent and shaped (they are malleable).

7. 27/05/2016 Giant structures (“lattices”) - Summary + + + + +++ + + 1. Diamond – a giant covalent structure with a very ____ melting point due to ______ bonds between carbon atoms 2. Graphite – carbon atoms arranged in a layered structure, with free _______ in between each layer enabling carbon to conduct _________ 3. Sodium chloride – a giant ionic lattice with _____ melting and boiling points due to ______ forces of attraction. Can conduct electricity when _______. 4. Metals – the __________ in metals are free to move around, holding the structure together and enabling it to conduct _________

8. 27/05/2016Nanoscience Nanoscience is the study of structures that are 1- 100nm in size (roughly a few hundred atoms). Nano-particles have different properties to the same materials in bulk. They have a high surface area to volume ratio. They are being used to develop: –New computers - new catalysts –new coatings - new medicines –Highly selective sensors –Stronger, lighter construction materials.

9. 27/05/2016 12.2 - Test 1.Give 2 examples of ionic structures.(2) 2.Do ionic structures have high or low melting points?(1) Explain.(2) 3.Discuss the conductivity of ionic compounds.(3)

10. 27/05/2016 12.2 - Test 4.What types of structure are diamond and graphite?(1) 5.Explain why graphite conducts heat and electricity, but diamond does not.(4) 6. What type of structure is water?(1) –Why does it have a relatively low melting point?(2)

11. 27/05/2016 12.2 - Test 7.Explain why metals conduct electricity.(3) 8.Explain why metals are malleable (can be easily shaped). (2) 9.What is nanoscience?(1) What is it being used to produce?(3)