A chlorine atom contains 17 electrons, 18 neutrons and 17 protons - Edexcel - GCSE Chemistry - 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 - Question 2 - 2018 - Paper 1
Step 1
State the mass number of this chlorine atom.
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Answer
The mass number of a chlorine atom can be calculated by adding the number of protons and neutrons. Here, chlorine has 17 protons and 18 neutrons. Therefore, the mass number is:
17+18=35
Step 2
Give the electronic configuration of this chlorine atom.
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Answer
The electronic configuration of a chlorine atom, which has 17 electrons, is written as:
1s22s22p63s23p5
This shows that there are 2 electrons in the first shell, 8 in the second shell, and 7 in the third shell.
Step 3
Describe what you would see if damp, blue litmus paper is placed into chlorine gas.
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When damp, blue litmus paper is placed into chlorine gas, the paper will first turn red. This color change indicates that chlorine is an acidic gas. After a while, the litmus paper may bleach and turn white, indicating that the chlorine gas has oxidizing properties.
Step 4
State why the litmus paper turns red.
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The litmus paper turns red because the solution formed by hydrogen chloride (HCl) in water is acidic, containing hydrogen ions (H⁺). This reaction leads to a decrease in pH, which causes the blue litmus paper to change color.
