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7 (a) Silicon dioxide has a very high melting point - AQA - GCSE Chemistry - Question 7 - 2014 - Paper 1
Question 7
7 (a) Silicon dioxide has a very high melting point. Other substances are added to silicon dioxide to make glass. Glass melts at a lower temperature than silicon dio... show full transcript
Worked Solution & Example Answer:7 (a) Silicon dioxide has a very high melting point - AQA - GCSE Chemistry - Question 7 - 2014 - Paper 1
Step 1
Suggest why glass melts at a lower temperature than silicon dioxide.
Answer
Glass melts at a lower temperature than silicon dioxide because the other substances added disrupt the lattice structure of silicon dioxide. This disruption results in weaker bonds between the atoms, requiring less energy (heat) to break them.
Step 3
Complete the diagram to show the outer electrons in an oxygen molecule (O₂).
Answer
In the diagram, show two overlapping circles representing the two oxygen atoms. Each oxygen should have four outer electrons, with two bonding pairs (shared electrons) represented as dots or crosses in the overlapping area, and two lone pairs on each oxygen indicated outside the overlap.
Step 4
Describe the structure of a metal.
Answer
Metals have a crystalline structure characterized by a lattice arrangement of positive ions surrounded by a sea of delocalized electrons. This regular pattern allows for layers to slide over each other, contributing to the malleability and ductility of metals. The presence of these free electrons also facilitates electrical conductivity.