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This question is about oxygen and substances containing oxygen - AQA - GCSE Chemistry - Question 3 - 2017 - Paper 1
Question 3
This question is about oxygen and substances containing oxygen. 3 (a) (i) Complete Figure 4 to show the arrangement of the outer shell electrons in an oxygen molecu... show full transcript
Worked Solution & Example Answer:This question is about oxygen and substances containing oxygen - AQA - GCSE Chemistry - Question 3 - 2017 - Paper 1
Step 1
Complete Figure 4 to show the arrangement of the outer shell electrons in an oxygen molecule.
Answer
The outer shell of an oxygen molecule consists of two oxygen atoms, each having six electrons in their outer shell. These can be represented using dots and crosses in a diagram, where one atom's electrons are shown as dots (•) and the other atom's as crosses (×). Therefore, the arrangement would look something like:
••
•××××
••
This diagram shows two bonding pairs of electrons between the two oxygen atoms.
Step 2
Step 3
Explain why oxygen has a low boiling point.
Answer
Oxygen has a low boiling point due to weak intermolecular forces that exist between the oxygen molecules. These forces, known as Van der Waals forces, require very little energy to overcome, leading to oxygen transitioning from a liquid to a gaseous state at relatively low temperatures.
Step 4
Step 5
Describe what happens, in terms of electrons, when magnesium atoms react with oxygen atoms to produce magnesium oxide.
Answer
When magnesium atoms react with oxygen atoms, magnesium loses two electrons to achieve a noble gas configuration, forming magnesium ions (Mg²⁺). In contrast, oxygen gains these two electrons to become oxide ions (O²⁻). This transfer of electrons leads to the formation of ionic bonds between the positively charged magnesium ions and the negatively charged oxide ions.
Step 6
Step 7
Explain, in terms of structure and bonding, why silicon dioxide is used to line furnaces.
Answer
Silicon dioxide has a high melting point because it consists of a giant covalent structure, where each silicon atom is covalently bonded to four oxygen atoms in a tetrahedral arrangement. This extensive network of strong bonds requires a significant amount of energy to break, making silicon dioxide suitable for lining furnaces that operate at high temperatures.