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

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

M5 Patterns of Reactivity I: Displacement Reactions

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


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.


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.


Reactive• 1. What does the word reactive actually mean?

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? It is very reactive because the outer electron is very easily

removed.


3. Displacement (reactions)

•

To displace:

to kick something out and take its place.


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.


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


Displacement of StanTake a hike

Stan. I wanna be with PIGGY!

CARTMAN

• And as you all know, Cartman gets what he wants!

STAN PIGGY


Displacement of Stan

CARTMAN - PIGGYSTAN

I have been Displaced!!


Displacement of Stan

• Who is the stronger (bully) -- CARTMAN or STAN ?

What happened to STAN and Why ?


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


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…


Displacement of Kyle

STAN

I have been displaced!!!

Kyle


Displacement of Kyle

• Who is the stronger (bully) -- Kyle or STAN ?

What happened to Kyle and

Why ?


Kenny’s Story• The following day, while Kenny was trying

to get some one-one time with piggy… Take a walk

Kenny!!!

KennyKyle


Displacement of Kenny

I have been displaced!!!

Kenny Kyle


Displacement of Kenny• Who is the stronger (bully) --

Kenny or KYLE ? What happened to Kenny and

Why ?


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…


Kenny’s Day?• Chef had to come along and console Kenny!!

Come now. Your time will come!!Arwa golle

wawna toz!


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?

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

Displacement Reaction• What really happened when we put

Sodium into water?

• Na + H2O →

• 2Na + H2O →H2 + 2NaO


Group 1 Metals: Reaction with water• Alkali metals react with water to form their

hydroxide and hydrogen gas: 2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g) 2K(s) + 2H2O(l) 2KOH(aq) + H2(g)

• In general: 2M(s) + 2H2O(l) 2MOH(aq) + H2(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

M H-O-H M-OH H-HM H-O-H M-OH Can you tell what is Piggy in this case?


Group 1 Metals: Reaction with water• Alkali metals react with water to form their

hydroxide and hydrogen gas: 2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g) 2K(s) + 2H2O(l) 2KOH(aq) + H2(g)

• In general: 2M(s) + 2H2O(l) 2MOH(aq) + H2(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

M H-O-H M-OH H-HM H-O-H M-OH Can you tell what is Piggy in this case?


Reaction of Group 2 Metals with Water

Fig. 2Fig. 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.

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


Reactivity of Group 2Mg(s) + H2O (g) MgO + H2(g)

• Here, again, notice we can say that a displacement reaction has taken place. – Magnesium has taken the place of H2 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.


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.

Documents

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