3. On your assignment sheet… In one box answer the following questions – Make three brief observations – What type of reaction was it? – Write the balanced chemical equation

4. M5 Patterns of Reactivity I: Displacement Reactions

5. M5 Patterns of Reactivity: Displacement Rxns Slide 5 of 29 Learning Objectives Concepts: –reaction, reactivity, displacement, metal, order of reactivity Skills: –Describe and explain the properties of metals. –Describe and explain group reactivity trends for groups 1 in their reaction with water

6. M5 Patterns of Reactivity: Displacement Rxns Slide 6 of 29 Chemistry of Metals 80% of all elements are metals. Fig 1. Metals & non-metals in the periodic table Other common metals include iron, calcium and magnesium. Fig 2. The amount of different metals in the earths surface The most abundant metal in the earths surface is aluminum.

7. M5 Patterns of Reactivity: Displacement Rxns Slide 7 of 29 Reactivity Series Remember, when metals react, they lose electrons to become positively charged ions. Some metals lose electrons easily, this makes them very reactive. –For example, potassium reacts explosively with cold water and acids. Other metals react more slowly. –A piece of iron takes several days to rust when it is placed in water. A few metals, such as gold and silver are very unreactive, they do not combine with other elements, they never rust or oxidize.

8. M5 Patterns of Reactivity: Displacement Rxns Slide 8 of 29 Reactive 1. What does the word reactive actually mean? It means how easily a chemical combines with another to form a compound. It means how easily a chemical combines with another to form a compound. In the case of a metal, it’s how easily it will lose electrons to form a cation (or the difficulty with which its ion will part with the anion to which it is bonded). 2. Why is potassium very reactive? 2. Why is potassium very reactive? It is very reactive because the outer electron is very easily removed. It is very reactive because the outer electron is very easily removed.

9. M5 Patterns of Reactivity: Displacement Rxns Slide 9 of 29 3. Displacement ( reactions ) To displace : to kick something out and take its place.

10. M5 Patterns of Reactivity: Displacement Rxns Slide 10 of 29 Displacement The South Park Way Cartman, Stan, Kyle and Kenny are good friends…well most of the time…except when it comes to the question of who gets to play with piggy. Chef, of course tries to help settle any argument or console any kid. Piggy remains in a small pen waiting for one or more of the kids to come and play with it.

11. M5 Patterns of Reactivity: Displacement Rxns Slide 11 of 29 Displacement of Stan And today, Stan comes along to play with it. They are having a jolly good time until…guess who appears on the scene? STAN PIGGY

12. M5 Patterns of Reactivity: Displacement Rxns Slide 12 of 29 Displacement of Stan Take a hike Stan. I wanna be with PIGGY! CARTMAN And as you all know, Cartman gets what he wants! STANPIGGY

13. M5 Patterns of Reactivity: Displacement Rxns Slide 13 of 29 Displacement of Stan CARTMAN - PIGGY STAN I have been Displaced!!

14. M5 Patterns of Reactivity: Displacement Rxns Slide 14 of 29 Displacement of Stan Who is the stronger (bully) -- CARTMAN or STAN ? What happened to STAN and Why ?

15. M5 Patterns of Reactivity: Displacement Rxns Slide 15 of 29 Kyle’s Story The following day Kyle wakes up early and runs over to piggy and starts playing with it and having a grand ol’ time! Kyle

16. M5 Patterns of Reactivity: Displacement Rxns Slide 16 of 29 Displacement of Kyle Until Stan, having woken up a little late, gets around to Piggy’s sty to find Kyle spending some quality time with it. STAN Scram Kyle! Kyle Stan, remembering how Cartman treated him the other day…

17. M5 Patterns of Reactivity: Displacement Rxns Slide 17 of 29 Displacement of Kyle STAN I have been displaced!!! Kyle

18. M5 Patterns of Reactivity: Displacement Rxns Slide 18 of 29 Displacement of Kyle Who is the stronger (bully) -- Kyle or STAN ? What happened to Kyle and Why ?

19. M5 Patterns of Reactivity: Displacement Rxns Slide 19 of 29 Kenny’s Story The following day, while Kenny was trying to get some one-one time with piggy… Take a walk Kenny!!! Kenny Kyle

20. M5 Patterns of Reactivity: Displacement Rxns Slide 20 of 29 Displacement of Kenny I have been displaced!!! Kenny Kyle

21. M5 Patterns of Reactivity: Displacement Rxns Slide 21 of 29 Displacement of Kenny Who is the stronger (bully) -- Kenny or KYLE ? What happened to Kenny and Why ?

22. M5 Patterns of Reactivity: Displacement Rxns Slide 22 of 29 Kenny’s Day? The following day, Kenny, remembering how he got displaced by Stan, woke up early so that he could cosy up to piggy. Kenny I would scram Kenny!! CARTMAN He groggily walks over to the sty to find…

23. M5 Patterns of Reactivity: Displacement Rxns Slide 23 of 29 Kenny’s Day? Chef had to come along and console Kenny!! Come now. Your time will come!! Arwa golle wawna toz!

24. M5 Patterns of Reactivity: Displacement Rxns Slide 24 of 29 Displacement Who is the stronger (bully) -- Cartman or Kenny ? What happened to Kenny and Why ? Who is the biggest bully of them all? What is the hierarchy of the bullies? Who would win the company of piggy if Kyle were to come along and find Cartman with piggy? Why?

25. Who would win the company of piggy if Stan were to come along and find Kenny with piggy? Why? The pattern of reactivity of metals and two non-metals (carbon and hydrogen) will be established by looking at displacement reactions these elements are involved in. Displacement

26. Displacement Reaction What really happened when we put Sodium into water? Na + H 2 O → 2Na + H 2 O →H2 + 2NaO

27. M5 Patterns of Reactivity: Displacement Rxns Slide 27 of 29 Group 1 Metals: Reaction with water Group 1 Metals: Reaction with water Alkali metals react with water to form their hydroxide and hydrogen gas: 2Na (s) + 2H 2 O (l)  2NaOH (aq) + H 2(g) 2K (s) + 2H 2 O (l)  2KOH (aq) + H 2(g) In general: 2M (s) + 2H 2 O (l)  2MOH (aq) + H 2(g) Where M = group 1 metal Group 1 metals displaces hydrogen from water and therefore group 1 metals are more reactive than hydrogen. The above equation when represented as shown below should help you understand it better Can you tell what is Piggy in this case?

28. M5 Patterns of Reactivity: Displacement Rxns Slide 28 of 29 Group 1 Metals: Reaction with water Group 1 Metals: Reaction with water Alkali metals react with water to form their hydroxide and hydrogen gas: 2Na (s) + 2H 2 O (l)  2NaOH (aq) + H 2(g) 2K (s) + 2H 2 O (l)  2KOH (aq) + H 2(g) In general: 2M (s) + 2H 2 O (l)  2MOH (aq) + H 2(g) Where M = group 1 metal Group 1 metals displaces hydrogen from water and therefore group 1 metals are more reactive than hydrogen. The above equation when represented as shown below should help you understand it better Can you tell what is Piggy in this case?

29. M5 Patterns of Reactivity: Displacement Rxns Slide 29 of 29 Reaction of Group 2 Metals with Water Fig. 2 Fig. 1 hydrogen Group 2 metals like magnesium and calcium react very slowly with cold water (fig.1), but quickly with steam (fig.2). Solid white magnesium oxide powder and hydrogen gas and are produced.

30. Reaction of Group 2 Metals with Water Put on your assignment sheet…… Measure and cut a 10cm strip of Mg Measure and record the mass of the Mg Bend Mg and place in 10ml graduated “see example” Watch set up for 5 minutes and record any observations

31. M5 Patterns of Reactivity: Displacement Rxns Slide 31 of 29 Reactivity of Group 2 Mg(s) + H 2 O (g)  MgO + H 2 (g) Here, again, notice we can say that a displacement reaction has taken place. –Magnesium has taken the place of H 2 in water. Based on that displacement reaction it can be concluded that magnesium is also more reactive than hydrogen. And of course, you know that going down group 2, reactivity increases, for the same reason that reactivity of group 1 metals increases going down the group. So, for instance, calcium is more reactive than magnesium. –Calcium reacts with cold water but nowhere near as vigorously as sodium or lithium.

32. M5 Patterns of Reactivity: Displacement Rxns Slide 32 of 29 Reactivity Going Across You also know from last year that Sodium is more reactive than Magnesium. What’s the evidence? Sodium reacts with cold water while magnesium requires steam. Not only that, you can also now tell that sodium is more reactive than calcium. Further potassium is more reactive than sodium, which in turn is more reactive than calcium, which in turn is more reactive than magnesium etc. So, the order of reactivity for the four metals is: K > Na > Ca > Mg. Next we will look at the relative reactivity of other metals and place them in this order.