Home / iGCSE Chemistry 0620 Extended – 2.1 Elements, compounds and mixtures- Exam Style Questions Paper 4
Most-appropriate topic codes (Cambridge IGCSE Chemistry 0620):
• Topic 2.1 — Atomic structure and the Periodic Table
(a)(i) A, B, F
Atoms are electrically neutral species where the total number of protons exactly balances the total number of electrons. Particles A, B, and F satisfy this constraint seamlessly.
(a)(ii) D
An ion with a charge of 2- must possess exactly two more electrons than protons. Particle D contains 16 protons and 18 electrons, resulting in a net structural negative charge of 2-.
(a)(iii) C
Cations are positively charged ions that are formed when an atom loses valence electrons. Particle C contains 13 protons and only 10 electrons, corresponding to a stable $+3$ cation.
(b) 5
The atomic number represents the total proton count situated within an atom’s nucleus. Particle A contains 5 protons, which explicitly defines its atomic position as 5.
(c) 34
The total nucleon count is determined by summing together the protons and neutrons within the core. For particle D, this evaluates to $16 \text{ protons} + 18 \text{ neutrons} = 34 \text{ total nucleons}$.
(d) 2,8,8
Particle D has 18 electrons. These electrons are arranged by filling successive shells from inside out, accommodating 2 in the first shell, 8 in the second shell, and 8 in the third shell.
(e) 5
Particle F contains 15 protons, which belongs to phosphorus. Its electronic distribution profile is 2,8,5. Since it possesses 5 outer valence electrons, it resides in Group V.
(f) 2
Particle B has a proton count of 10, identifying it as neon. Its electrons fill two principal energy levels (2,8), indicating it belongs to Period 2 of the Periodic Table.