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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
In Figure 4, an oxygen molecule (O₂) consists of two oxygen atoms, each having six outer shell electrons. Use dots (•) to represent the electrons from one oxygen atom and crosses (×) to represent the electrons from the other. The arrangement should show that these two atoms share two pairs of electrons, indicating a double bond.
Step 2
Step 3
Explain why oxygen has a low boiling point.
Answer
Oxygen has a low boiling point due to weak intermolecular forces present between its molecules. These weak Van der Waals forces require little energy to overcome, resulting in a relatively low boiling point compared to substances with stronger intermolecular bonds. Additionally, the small size of oxygen molecules contributes to lower energy requirements for phase changes.
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 structure, becoming Mg²⁺ ions. Meanwhile, oxygen atoms gain these two electrons, forming O²⁻ ions. This transfer of electrons results in the formation of ionic bonds between the positively charged magnesium ions and the negatively charged oxide ions in magnesium oxide.
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 as a result of its strong covalent bonding within a giant covalent structure. A large amount of energy is required to break these strong bonds, which allows silicon dioxide to remain stable and not melt under the high temperatures of 1500 °C found in furnaces. Additionally, the continuous network of silicon and oxygen atoms in its structure provides excellent thermal stability.