Combining ions: Ionic bonding and dot-cross diagrams 15/05/2019 You will need to know how to: Work out the formula of the ion. Be able to draw the ion. Be able to write the formula of the ionic compound. Now you try: Lithium Fluoride Beryllium Sulfide Aluminium fluoride

How many of these fluoride ions would we need? 15/05/2019 Answers + - 2+ 2- Li F Be S 3+ - Al F How many of these fluoride ions would we need?

Title: Properties of Ionic Compounds Complete the activities listed below 15/05/2019 Lesson aim: Know how ionic compounds form and the structure they take on. Explain the physical properties (e.g. melting point) of ionic compounds. On your mini-whiteboard, sketch what you think ionic compounds look like: Label on any ions. Show any charges there might be. https://www.youtube.com/watch?v=LnJTSSJ6Bqc Key words: Opposite charges, lattice, electrostatic, energy, free-flowing.

Ionic compounds are formed due to: (Giant) Ionic Lattice 15/05/2019 Ionic compounds are formed due to: Electrostatic forces of attraction… Between oppositely charged ions… That arrange themselves in an alternating pattern: + - + - + - + -

(Giant) Ionic Lattice 15/05/2019 You will notice that each ion is surrounded by SEVERAL ions of the opposite charge. Ionic compounds contains LOTS of ions… Therefore lots of electrostatic forces of attraction holding together the ions… Meaning that A LOT of energy is required to melt an ionic compound. The ions are fixed in place.

Here’s an expanded diagram 15/05/2019 A section of a giant ionic lattice (sodium chloride – the stuff you put on your chips!)

Melting and Boiling Points 15/05/2019 Electrostatic forces of attraction are very strong – far stronger the your usual intermolecular forces! To separate ions and have changes of state (solid  liquid  gas) energy must be put in to break apart each and every ion. This requires LOTS of energy – this means they will only melt at very higher temperatures…and boil at even higher temperatures!

True or False Quiz: 15/05/2019 Ionic compounds are made of alternating positive and negative ions. Opposite charges repel each other. These are called electrostatic forces of repulsion. Ions packed together in an ordered, regular structure is called a giant ionic lattice. Electrostatic forces of attraction are very strong, stronger than intermolecular forces of attraction. Ionic compounds have very low melting and boiling points.

Past paper Questions 15/05/2019 Sodium atom loses/transfer an/one electron. Chlorine atom gains an/one electron. Mention of involvement of electrons in the outer shell for sodium and chlorine.

15/05/2019 Past paper Questions

Electrical Conductivity https://www.youtube.com/watch?v=iNN0ggzrA3E 15/05/2019 Watch the video about ionic compounds and electrical conductivity (We’ll play it twice). Answer the questions on the sheet as we go along. Small electrical current. Dissolved salts. No, ionic substances do not conduct when solid. Molten (heated until liquid); dissolved in water (aqueous solution). Contains charged particles…that are free to move. In ionic solids the ions are held in fixed positions  Cannot carry charge. Molten or dissolved: charged ions are free to move!

Ionic or Not? https://www.youtube.com/watch?v=4WillWjxRWw 15/05/2019 From what you know now you should be able to tell whether a substance is ionic or not by its electrical conductivity. Identify, from the video, whether or not these are ionic substances: Tap water: Distilled water: Salt water: Hydrochloric acid (HCl): Sodium hydroxide (NaOH): Sugar water: Vinegar (mostly CH3COOH): Ethanol (CH3CH2OH): Barium Sulfate (BaSO4): Make predictions first, then record your answers on a mini-whiteboard.

Barium Sulfate: A surprising result? 15/05/2019 It is an ionic compound…(positive ion attracted to negative ion – held together by electrostatic forces of attraction) It does not dissolve in water (is insoluble)… There does not form a solution to conduct electricity… Because its charged ions remain fixed and unable to carry charge.