22.1 Reactions of period 3 elements Flashcards
Properties of the first 3 period 3 elements
Sodium, magnesium and aluminium
They are metallic
So are shiny when first exposed to air, conduct electricity, and react with dilute acids to give hydrogen and salts
Describe the conduction of silicon
. Metalloid so conducts electricity to some extent which is useful
Phosphorus, sulfur and chlorine properties
. Non-metals
They don’t conduct electricity and have low melting and boiling points
Argon properties
It’s a noble gas, chemically unreactive
What two metals from period 3 react with water
Sodium and magnesium
How does sodium react with water
. Vigorous reaction
. Sodium floats on top of the water and fizzes rapidly
. It melts because of the heat energy released by the reaction
. A strongly alkaline solution of sodium hydroxide is formed
The equation of sodium and water
2Na(s) +2H20(l) –> 2NaOH(aq) + H2(g)
How does magnesium react with water
. It is a very slow reaction at room temperature
. Only a few bubbles of hydrogen are formed after days
The resulting solution is less alkaline than with sodium because magnesium hydroxide is only sparingly soluble (PH 10)
How can you make the reaction between magnesium and water faster
What is the reaction for this reaction, and what type of reaction is it
. React magnesium with steam
Mg(s) + H20(g) –>
MgO + H2(g)
Its a redox reaction as the oxidation state of the metal increases from 0 to 2+ and that of the hydrogen decreases from 1+ to 0
Equation of magnesium with liquid water
Mg(s) + 2H20(l) —>
Mg(OH)2(aq) + H2(g)
How do period 3 elements react with oxygen
Eg Sodium
All elements in period 3 are relatively reactive so directly react with it.
2Na(s) +1/2O2(g) –>
Na2O(s)
Sodium burns brightly in air with a yellow flame to form white sodium oxide
magnesium + oxygen
2Mg(s) + O2(g) —>
2MgO(s)
It makes magnesium oxide
How do magnesium and oxygen react
A strip of magnesium ribbon burns in air with a bright white flame.
It produces a white powder called magnesium oxide
How does aluminium react with oxygen
When aluminium powder is heated and then lowered into a gas jar of oxygen, it burns brightly to make aluminium oxide which is a white powder
Equation for aluminium and oxygen
4Al(s) + 3O2(g) —> 2Al2O3(s)
Aluminium is a reactive metal, so how is it protected from rusting
Everyday uses
. Its oxide forms a strongly bonded protective layer over it which protects it from reacting even further
That’s why aluminium is seen as an unreactive metal and has everyday uses eg saucepan or window frame
How does silicon react with oxygen
Give equation
Silicon will also form an oxide if heated strongly in oxygen
Si(s) + O2(g) –> SiO2(s)
How does phosphorus react with oxygen
Why is there both red and white phosphorus
. Red phosphorus must be heated before it will react with oxygen
. White phosphorus spontaneously ignites in air and the white smoke of phosphorus pentoxide is given off
Red and white are allotropes of phosphorus- the same element with the particles arranged differently
What is the equation for phosphorus and oxygen
What is produced when oxygen supply is limited
4P(s) + 5O2(g) –> P4O10(s)
Makes phosphorus pentoxide
P2O3 phosphorus trioxide is formed
How does sulfur react with oxygen
.When sulfur powder is heated and lowered into a glass jar of oxygen
. It burns with a blue flame to form colourless gas sulfur dioxide (and a little sulfur trioxide also forms)
Equation of sulfur and oxygen
S(s) + O2(g) —> SO2(g)
What occurs in all the redox reactions of period 3 elements and oxygen
. The oxidation state of the period 3 element increases so that of oxygen decreases from O to -2 in each case
The oxidation number of the period 3 element increases across the period
