LC Chem Final Revision

Atomic Structure

2026 Mock Q4

(a)    (i)    36 ✓    (ii)    45 ✓

(b)    atomic orbital: a region in space where there is a high probability of finding an electron ✓


Q5

(a)    (i)    gold ✓

        (ii)    alpha particles ✓


  • most of the alpha particles passed through the gold foil ✓

  • a small number of particles were deflected at large angles ✓

  • a tiny number of particles were reflected back along their original path ✓


  • the atom is mostly empty space with small, dense, positive core called a nucleus. ✓


Q10

(a)    (i)    isotope: atoms of the same element with the same atomic number but different mass numbers due to different numbers of neutrons in the nucleus ✓

        (ii)    mass number: the number of neutrons and protons in the atom of an element ✓


principle of mass spectrometry: atoms of an element are separated based on their mass numbers and deflected at different angles due to their mass numbers


  • ionisation ✓

  • acceleration ✓

  • separation ✓

  • deflection ✓


Mr = 63.62 ✓


2025 Q4

(b)    (i)    28 X 24   (ii)    21 ✓


Q5

(a)    (i)    mass spectrometer ✓

        (ii)    the nucleus of the bromine-79 atom has 2 less neutrons than the nucleus of the bromine-81 atom X give number of protons and number of neutrons

        (iii)    MRR: the average mass numbers of isotopes of an element as they occur naturally, taking the abundances into account, based on the 1/12th mass of the carbon-12 isotope ✓

        (iv)    79.99 ✓


2025 Mock Q5

(a)    the minimum energy required to completely remove the most loosely bound electron from a neutral gaseous atom in its ground state ✓


(i)   the sulfur atom has a greater atomic radius than the chlorine atom. This means the outermost electron in a sulfur atom experiences a greater shielding effect from inner electrons and a less effective nuclear charge than the outermost electron of a chlorine atom. this means it requires less energy to remove the outermost electron from sulfur. ✓

the phosphorous atom has a half filled outer sublevel. This increases its stability requiring more energy to remove its outermost electron giving it a higher first ionisation energy than sulfur, which has a 2 electrons sharing an orbital in its 3P sublevel. ✓

(ii)    the first ionisation energy of elements decreased down a group due to increased atomic radius from oxygen to sulfur. ✓