11.2 Activities

Activity 1. Match the terms with their definitions

1 mantle	A-deoxyribonucleic acid, a self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information
2 supernova	B-a substance which is easily set on fire
3 mixture	C-the region of the earth's interior between the crust and the core, believed to consist of hot, dense silicate rocks (mainly peridotite)
4 DNA	D-a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass
5 inflammable	E-the product of the random distribution of one substance through another without any chemical reaction, as distinct from a compound

Activity 2. Mark the sentences “True” or “False”

1) Magnesium alloys are classified into four groups.

2) The mechanical properties of magnesium, especially the tensile strength, are very low and therefore pure magnesium is not employed in engineering.

3) The metal itself was first produced by Antoine Bussy in England in 1808 using electrolysis of a mixture of magnesia and mercuric oxide.

4) Magnesium ions are sweet to the taste.

5) Magnesium is the fifth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle.

Activity 3. Match the beginnings of sentences to their endings

1 The relative abundance of magnesium is related to the fact that	A- using electrolysis of a mixture of magnesia and mercuric oxide.
2 The metal itself was first produced by Sir Humphry Davy in England in 1808	B- are aluminium, zinc and manganese.
3 The principal alloying elements in magnesium alloys	C- though their castability is inferior to that of aluminium-base alloys.
4 Magnesium casting alloys MЛ4 and MЛ5 are widely used as foundry material	D- with a dazzling flame, developing a great deal of heat.
5 Magnesium is very inflammable and burns	E- it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon

Activity 4. Explain the terms

an alkaline earth metal, highly reactive, electrolysis, oxidation resistance

Activity 5. Complete the sentences with proper words from the text

1) The name magnesium originates from the _____word for a district in Thessaly called Magnesia.

2) Magnesium has a specific _____of approximately 1.7.

3) The mechanical properties of magnesium, especially ____, are very low and therefore pure magnesium is not employed in engineering.

4) _____ of magnesium is 650° C; its boiling point is _____.

5) The free metal burns with a characteristic _____ light, making it a useful ingredient in flares.

Activity 6. Make a short summary of the text; read about the production of magnesium and its alloys in your region and discuss it