A chlorine atom contains 17 electrons, 18 neutrons and 17 protons - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2018 - Paper 1
Question 2
A chlorine atom contains 17 electrons, 18 neutrons and 17 protons.
(i) State the mass number of this chlorine atom.
(ii) Give the electronic configuration of this ... show full transcript
Worked Solution & Example Answer:A chlorine atom contains 17 electrons, 18 neutrons and 17 protons - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2018 - Paper 1
Step 1
State the mass number of this chlorine atom.
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Answer
The mass number of an atom is calculated by adding the number of protons and neutrons. For chlorine, this is:
Mass Number = Number of Protons + Number of Neutrons
Mass Number = 17 + 18 = 35
Step 2
Give the electronic configuration of this chlorine atom.
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Answer
The electronic configuration of chlorine (with 17 electrons) is determined based on the distribution of electrons in various energy levels. Chlorine's electronic configuration is:
2, 8, 7
This indicates that there are 2 electrons in the first shell, 8 in the second shell, and 7 in the outer shell.
Step 3
Describe what you would see if damp, blue litmus paper is placed into chlorine gas.
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Answer
When damp, blue litmus paper is introduced to chlorine gas, it first turns red before bleaching white. The red color indicates the acidity, and the bleaching effect occurs due to the oxidizing nature of chlorine, which removes the color from the litmus paper.
Step 4
State why the litmus paper turns red.
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Answer
The litmus paper turns red because hydrogen chloride (HCl), which is formed when chlorine dissolves in water, is an acidic solution. The presence of hydrogen ions (H⁺) in the solution is what causes the blue litmus paper to change color.
