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Reactions

Noadswood Science, 2011

+Reactions

To be able to describe how similar metals react with water and oxygen, and why noble gases do not react

Wednesday, April 19, 2023

+Reactivity

What metals are reactive and which are not?

Can you make a list of reactive metals?

Why is sodium not used for cutlery?

Why is magnesium not used for car bodies?

Why can people wear gold?

How are these metals produced?

+Reactivity

Some metals are extremely reactive, whilst others are not – the reactivity series shows how reactive metals are…

PotassiumSodiumCalciumMagnesiumAluminium

(Carbon)ZincIronLead

(Hydrogen)CopperSilverGoldPlatinum

+Metal + Water

Some metals do not react with water (such as gold and silver), but others do…

Watch the demo of some more reactive metals being placed in water – the metal reacts with the water forming a metal hydroxide, and as it does it releases hydrogen (which can sometimes catch alight)!

+Metal + Water

When a metal reacts with water the products are a metal hydroxide and hydrogen gas…

Metal + Water Metal Hydroxide + Hydrogen

Write out the equations for the following (word and symbol) Sodium reacting with water Potassium reacting with water Lithium reacting with water

+Metal + Water

Metal + Water Metal Hydroxide + Hydrogen

Sodium + Water Sodium Hydroxide + Hydrogen2Na (s) + 2H2O (l) 2NaOH (aq) + H2 (g)

Potassium+ Water Potassium Hydroxide + Hydrogen2K (s) + 2H2O (l) 2KOH (aq) + H2 (g)

Lithium + Water Lithium Hydroxide + Hydrogen2Li (s) + 2H2O (l) 2LiOH (aq) + H2 (g)

+Metal + Oxygen

Some metals do not react with water (such as gold and silver), but others do…

Watch the videos of some metals reacting in oxygen…

+Reactivity

Potassium Burning In Air

+Reactivity

Sodium Burning In Oxygen

+Metal + Oxygen

When a metal reacts with oxygen the product is a metal oxide

Metal + Oxygen Metal Oxide

What is the word and symbol equation for the reaction between sodium and oxygen?

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+Metal + Oxygen

Metal + Oxygen Metal Oxide

Sodium + Oxygen Sodium Oxide4Na (s) + O2 (g) 2Na2O (s)

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+Reactivity

Compare the reactivity series to where the elements are found within the periodic table – what relationship is there?

+Electron Structure & Reactivity

There is a definite pattern between the placement of a metal on the periodic table and how reactive it is – the most reactive metals are located in groups I and II, with the least reactive metals being within the transition metals, placed in the centre of the periodic table, between groups II and III – they are generally hard and dense, and less reactive than the alkali metals

+Reactivity – Very Reactive

The electron structure of an atom affects how reactive it is – a shell with just one electron in is it keen to ‘get rid’ of this so they have a full outer shell

Elements within group I (lithium, sodium, potassium etc…) and group II (magnesium, calcium, strontium etc…) have just one or two electrons to ‘get rid of’ before they have a full outer shell, and as such are extremely reactive

The most reactive metals are found within group I and II

+Reactivity – Not Reactive

Electron structure of an atom affects how reactive it is – a shell with three of four electrons will find it very difficult to gain / loose enough electrons to have a full outer shell

Elements within group III and group IV (including the transition metals such as zinc, silver and gold) have lots of electrons to gain / lose before they have a full outer shell, and as such as quite un-reactive

This is why metals such as gold can be found as ‘pure’ – they are so un-reactive that they have not reacted with other chemicals for billions of years

+Reactivity In Groups

As atoms get bigger they have more full shells of electrons – each new row has one more full shell

The number of outer electrons is the same for each element within a group

As you go do the group the outer shell of electrons is further from the nucleus – the inner shells provide shielding from the attraction of the +ve nucleus

As metal atoms get bigger the outer electron is more easily lost – metals are more reactive as you descend down group I and group II