1. Hydroxides & Oxides D. Crowley, 2007

2. Hydroxides & Oxides To be able to describe the reaction between metals + water and metals + oxygen To be able to describe the reaction between metals + water and metals + oxygen

3. Metal or Non-metal? Using the sheet, cut out the summary for metals & non-metals Using the sheet, cut out the summary for metals & non-metals Stick these into your books Stick these into your books

4. Metals & Non-metals Metals: conduct electricity; conducts heat well; is malleable, I.e. can bend without breaking; is usually a hard material; has strong forces between atoms which are very close together Metals: conduct electricity; conducts heat well; is malleable, I.e. can bend without breaking; is usually a hard material; has strong forces between atoms which are very close together Non-metals: does not usually conduct electricity; does not conduct heat well; is brittle and not strong; usually has a low melting point; has weak forces as the atoms are not very close together Non-metals: does not usually conduct electricity; does not conduct heat well; is brittle and not strong; usually has a low melting point; has weak forces as the atoms are not very close together

5. Reaction Today you are doing an experiment Today you are doing an experiment You are going to see what happens when you react some metals with warm water You are going to see what happens when you react some metals with warm water You’ll be testing for hydrogen, and identifying the pH You’ll be testing for hydrogen, and identifying the pH

6. Experiment You will need a Bunsen burner (on the safety flame) You will need a Bunsen burner (on the safety flame) A heat-proof mat A heat-proof mat Some splints Some splints A boiling tube (half filled with water) A boiling tube (half filled with water) 1 piece of magnesium, calcium & copper 1 piece of magnesium, calcium & copper

7. Procedure Place one of the metals in the boiling tube, and heat gently Place one of the metals in the boiling tube, and heat gently After a short while light a splint, and place this in the end of the boiling tube - has hydrogen been produced - how will you know? After a short while light a splint, and place this in the end of the boiling tube - has hydrogen been produced - how will you know? Finally, add a few drops of UI in, and record the pH Finally, add a few drops of UI in, and record the pH

8. Findings Hopefully you found that when some metals were placed in water they reacted Hopefully you found that when some metals were placed in water they reacted Hydrogen was produced (squeaky pop) Hydrogen was produced (squeaky pop) The pH also changed - it went from neutral to alkaline (purple) The pH also changed - it went from neutral to alkaline (purple) However not all the metals react - so some are reactive, others are not However not all the metals react - so some are reactive, others are not Watch the demo of some very reactive metals… Watch the demo of some very reactive metals…

9. Key Point When a metal reacts with water, it produces a metal hydroxide + hydrogen When a metal reacts with water, it produces a metal hydroxide + hydrogen metal + water  metal hydroxide + hydrogen

10. Equations Some metals react with water, forming a hydroxide and releasing hydrogen… Some metals react with water, forming a hydroxide and releasing hydrogen… The copper did not do anything in the water (no reaction) The copper did not do anything in the water (no reaction) The magnesium did not do much in the water - you may have got a slight pop (slight reaction) The magnesium did not do much in the water - you may have got a slight pop (slight reaction) The calcium was more reactive in the water - it produced a squeaky pop (stronger reaction) The calcium was more reactive in the water - it produced a squeaky pop (stronger reaction)

11. Equations Remember: metal + water  metal hydroxide + hydrogen Calcium + Water  Calcium hydroxide + Hydrogen Ca (g) + 2H 2 O (l)  Ca(OH) 2 (aq) + H 2 (g) Magnesium + Water  Magnesium hydroxide + Hydrogen Mg (g) + 2H 2 O (l)  Mg(OH) 2 (aq) + H 2 (g)

12. Reactivity So, some metals are un-reactive in water - such as copper and gold So, some metals are un-reactive in water - such as copper and gold This is why copper pipes at great at carrying water, and you can wear gold safely This is why copper pipes at great at carrying water, and you can wear gold safely However others are more reactive, such as calcium and magnesium… However others are more reactive, such as calcium and magnesium…

13. Summary Metals differ in how reactive they are - some are very reactive, others are less so Metals differ in how reactive they are - some are very reactive, others are less so Some metals react with water, producing a metal hydroxide + hydrogen (e.g. caclium) Some metals react with water, producing a metal hydroxide + hydrogen (e.g. caclium) Metal + water  metal hydroxide + hydrogen