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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). 2 (a) (i) A carbon atom has six electrons. Complete Figure 2 to... show full transcript
Worked Solution & Example Answer:This question is about compounds of carbon - AQA - GCSE Chemistry - Question 2 - 2017 - Paper 1
Step 1
2 (a) (i) Complete Figure 2 to show the electronic structure of a carbon atom.
Answer
The electronic structure of a carbon atom includes six electrons arranged as follows:
- Two electrons in the first energy level (shell).
- Four electrons in the second energy level (shell). This can be represented in Figure 2 as:
x
x
x x
Where each 'x' represents an electron.
Step 2
2 (a) (ii) 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 that are positively charged. Therefore, the nucleus of a carbon atom contains a total of twelve particles (protons and neutrons) with the following characteristics:
- Neutrons: no charge, located in the nucleus.
- Protons: positively charged, located in the nucleus.
Step 3
Step 4
Step 5
2 (c) (ii) 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 trend is attributable to the greater surface area and the resulting London dispersion forces that become stronger with increased molecular size.
Step 6
2 (c) (iii) 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 instance, hexane (C6H14) has a higher boiling point (69°C) than hexene (C6H12), which boils at 64°C. This observation can be attributed to the stronger intermolecular forces present in alkanes compared to alkenes.
Step 7
2 (d) Describe what happens to the alkane molecules in this investigation.
Answer
When liquid paraffin, which contains alkane molecules, is heated to a high temperature, the alkane molecules undergo a process known as cracking. This process involves breaking down large alkane molecules into smaller alkanes or even alkenes. This decomposition can produce gas and allows for the generation of various hydrocarbons with different properties.