iGCSE Chemistry 0620 Extended - 2.2 Atomic structure and the Periodic Table- Exam Style Questions Paper 2- New Syllabus
▶️ Answer/Explanation
Number of neutrons = nucleon number − proton number.
Atom 1 \(^{24}_{12}\mathrm{Mg}\): neutrons = 24 − 12 = 12 (equal to protons).
Atom 2 \(^{27}_{13}\mathrm{Al}\): neutrons = 27 − 13 = 14 (more than protons).
Atom 3 \(^{31}_{15}\mathrm{P}\): neutrons = 31 − 15 = 16 (more than protons).
Atom 4 \(^{40}_{18}\mathrm{Ar}\): neutrons = 40 − 18 = 22 (more than protons).
The atoms with more neutrons than protons are 2, 3, and 4. Looking at the given options, 2 and 4 is the correct pair.
✅ Answer: (C)
Atom 1 \(^{24}_{12}\mathrm{Mg}\): neutrons = 24 − 12 = 12 (equal to protons).
Atom 2 \(^{27}_{13}\mathrm{Al}\): neutrons = 27 − 13 = 14 (more than protons).
Atom 3 \(^{31}_{15}\mathrm{P}\): neutrons = 31 − 15 = 16 (more than protons).
Atom 4 \(^{40}_{18}\mathrm{Ar}\): neutrons = 40 − 18 = 22 (more than protons).
The atoms with more neutrons than protons are 2, 3, and 4. Looking at the given options, 2 and 4 is the correct pair.
✅ Answer: (C)
▶️ Answer/Explanation
An argon atom has atomic number 18, giving it 18 electrons arranged as 2,8,8. A chloride ion (Cl−) forms when a chlorine atom (17 electrons, configuration 2,8,7) gains one electron, resulting in 18 electrons with configuration 2,8,8. An aluminium ion (Al3+) loses 3 electrons (from 13 to 10), giving 2,8. A sodium ion (Na+) loses 1 electron (from 11 to 10), also giving 2,8. So only 1 and 4 are correct.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
The nucleon number (also called mass number) is defined as the total number of protons and neutrons in the nucleus of an atom. It is represented by the symbol \(A\). Option (A) defines atomic number (proton number), and options (B) and (C) are incorrect.
✅ Answer: (D)
✅ Answer: (D)