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This question is about compounds of carbon - AQA - GCSE Chemistry - Question 2 - 2017 - Paper 1
Question 2
This question is about compounds of carbon. Figure 2 shows an atom with two energy levels (shells). (a) (i) A carbon atom has six electrons. Complete Figure 2 to s... show full transcript
Worked Solution & Example Answer:This question is about compounds of carbon - AQA - GCSE Chemistry - Question 2 - 2017 - Paper 1
Step 1
Complete Figure 2 to show the electronic structure of a carbon atom.
Answer
The electronic structure of a carbon atom has six electrons distributed in the two energy levels as follows: two electrons in the first shell and four electrons in the second shell. This can be represented as:
- First energy level: 2
- Second energy level: 4
The diagram should reflect these arrangements with 'x' marking the electrons.
Step 2
Complete the following description about the central part of this carbon atom.
Answer
The central part is made up of six neutrons that have no electrical charge and six protons which are positively charged. Therefore, the central part is known as the nucleus, which holds these particles together.
Step 3
Step 4
Step 5
Describe the relationship between the number of carbon atoms in an alkane molecule and the boiling point of the alkane molecule.
Answer
As the number of carbon atoms in an alkane molecule increases, the boiling point of the alkane molecule also increases. This is due to the larger size of the molecule leading to stronger van der Waals forces that require more energy to overcome.
Step 6
Use the information in Table 2 to compare the boiling points of alkanes with the boiling points of alkenes.
Answer
The boiling points of alkanes are generally higher than those of alkenes that have the same number of carbon atoms. For example, hexane (C6H14) has a higher boiling point than hexene (C6H12) because alkanes are saturated and have only single bonds, which leads to stronger intermolecular forces compared to the unsaturated structure of alkenes.
Step 7
Describe what happens to the alkane molecules in this investigation.
Answer
When liquid paraffin (which contains alkanes) is heated to a high temperature, the alkane molecules undergo a process called cracking. This process causes larger alkane molecules to break down into smaller molecules, producing alkenes and other hydrocarbons, which may include gases. As heat is applied, these molecules may evaporate or boil off, resulting in the production of gaseous products.