A Data Booklet may be used.
| species | protons | neutrons | electrons |
|---|---|---|---|
| 23Na | 11 | 12 | 11 |
| 23Na+ | |||
| 32S2− | |||
| 56Fe3+ |
Source: Learners' Alley, Atomic Structure slides
CommonUnder certain conditions, a beam of 1H+ is deflected by +12°. Under the same conditions, calculate the angle of deflection of
Source: Learners' Alley, Atomic Structure slides
Source: Learners' Alley, Atomic Structure slides
Source: Learners' Alley, Atomic Structure slides
Write the full electronic configurations of
Source: Learners' Alley, Atomic Structure slides
578 1817 2745 11 577 14 842
State the Group of Y and identify Y.Source: Learners' Alley, Atomic Structure slides
496 4562 6912 9543
State the Group of Z, and explain why its second ionisation energy is so much larger than its first.Source: Learners' Alley, Atomic Structure slides
CommonWhat do the ions 18O2− and 19F− have in common?
Source: 2024 RI J2 Prelim P1 Q3
Which of the following species has no unpaired electrons?
Source: RVHS 2017 Promo, via EJC 2022 Atomic Structure Topical Revision, Q7
Which particle would, on losing an electron, have a half-filled set of p orbitals?
Source: IJC 2017 Promo, via EJC 2022 Atomic Structure Topical Revision, Q8
| species | number of protons | number of neutrons | number of electrons |
|---|---|---|---|
| 2H | |||
| 1H2+ | |||
| 3H3+ |
Source: 2024 NYJC J2 Prelim P2 Q1(c)
Magma, the molten rock under the Earth's surface, is rich in oxygen and silicon.
Source: 2022 HCI J1 Promo P3 Q1(a)
CommonIons of 28Si+ and X+ are passed through the same electric field. Their angles of deflection are 5.6° and 2.0° respectively.
Source: 2024 CJC J2 Prelim P2 Q1(d)
CommonThis question is about the first ionisation energies of the Period 3 elements, sodium to argon.
Source: EJC 2022 JC1 Atomic Structure Tutorial, A3(b) to (d)
ChallengeBoron and its compounds have many uses in industry.
Source: 2024 RI J2 Prelim P2 Q1(a)
| species | protons | neutrons | electrons | |
|---|---|---|---|---|
| 23Na+ | 11 | 12 | 10 | [1] |
| 32S2− | 16 | 16 | 18 | [1] |
| 56Fe3+ | 26 | 30 | 23 | [1] |
Exam tipCharge changes only the electrons: number of electrons = proton number − charge. Protons and neutrons never change in chemical reactions.
Angle of deflection = k × chargemass
For 1H+: +12 = k × +11, so k = 12
(a) 2H+: 12 × +12 = +6°[1]
(b) 4He2+: 12 × +24 = +6°[1]
(c) 16O2−: 12 × −216 = −1.5°[1]
Note2H+ and 4He2+ have the same charge to mass ratio, so they are deflected by the same angle.
% 26Mg = 100 − 79.0 − x = 21.0 − x
Ar = 24(79.0) + 25x + 26(21.0 − x)100 = 24.32[1]
1896 + 25x + 546 − 26x = 2432
x = 10.0[1]
Each atom is 35Cl with probability 0.75 and 37Cl with probability 0.25.
Mass 70 (35Cl–35Cl): 0.75 × 0.75 = 0.5625
Mass 72 (35Cl–37Cl or 37Cl–35Cl): 2 × 0.75 × 0.25 = 0.375
Mass 74 (37Cl–37Cl): 0.25 × 0.25 = 0.0625[1]
Relative abundances 70 : 72 : 74 = 9 : 6 : 1[1]
The large jump is between the 3rd and 4th ionisation energies, so Y has 3 electrons in its outermost shell. Group 13, and in Period 3, Y is aluminium.[1]
Group 1: the large jump is after the 1st ionisation energy.[1]
The 2nd electron is removed from an inner principal quantum shell, nearer the nucleus and less shielded, so it is much more strongly attracted.[1]
BThey have 10 neutrons in their nuclei.[1]
18O2−: 8 protons, 10 neutrons, 10 electrons. 19F−: 9 protons, 10 neutrons, 10 electrons.
CCu+[1]
| particle | electronic configuration | unpaired electrons |
|---|---|---|
| Fe3+ | [Ar] 3d5 | 5 |
| Ge+ | [Ar] 3d10 4s2 4p1 | 1 |
| Cu+ | [Ar] 3d10 | 0 |
| Ti3+ | [Ar] 3d1 | 1 |
NoteTransition metal ions lose their 4s electrons before their 3d electrons.
BN−[1]
| particle | before losing an electron | after losing an electron |
|---|---|---|
| C− | 1s2 2s2 2p3 | 1s2 2s2 2p2 |
| N− | 1s2 2s2 2p4 | 1s2 2s2 2p3 (half-filled) |
| O+ | 1s2 2s2 2p3 | 1s2 2s2 2p2 |
| P+ | 1s2 2s2 2p6 3s2 3p2 | 1s2 2s2 2p6 3s2 3p1 |
| species | protons | neutrons | electrons | explanation (not required) |
|---|---|---|---|---|
| 2H | 1 | 1 | 1 | each 2H atom has 1 electron, 1 proton and 1 neutron |
| 1H2+ | 2 | 0 | 1 | each 1H atom has 1 electron, 1 proton and 0 neutrons |
| 3H3+ | 3 | 3 × 2 = 6 | 2 | each 3H atom has 1 electron, 1 proton and 2 neutrons |
[1] for any 3 boxes correct[3]
Similarity (one of the following):[1]
The 3s and 3p orbital both belong to the third principal quantum shell or the 3s and 3p orbital can each hold a maximum of two electrons (of opposite spins).
Difference (one of the following):[1]
The 3s orbital is spherical while the 3p orbital has a dumb-bell shape or the 3s orbital is lower in energy than the 3p orbital.
NoteVague answers ("both hold electrons", "different energy") were rejected. Compare one 3s orbital with one 3p orbital, not the number of orbitals in each subshell.
Let the nucleon number of X be m.
1/281/m = 5.62.0[1]
m = 78.4, so X is Br.[1]
Across the period from sodium to argon, nuclear charge increases. There is the same number of inner shell electrons, so the shielding effect is approximately constant.[1]
Effective nuclear charge increases, so the electrostatic forces of attraction between the nucleus and the valence electron increase. More energy is needed to remove the valence electron.[1]
Mg: 1s2 2s2 2p6 3s2 Al: 1s2 2s2 2p6 3s2 3p1[1]
The 3p electron removed from Al is at a higher energy level than the 3s electron removed from Mg, so less energy is required to remove it.[1]
P: 1s2 2s2 2p6 3s2 3p3 S: 1s2 2s2 2p6 3s2 3p4[1]
In S, two electrons are paired in the same 3p orbital, so there is inter-electronic repulsion. Less energy is required to remove a 3p electron from S than from P.[1]
B3+: 1s2 C3+: 1s2 2s1
C3+ has one more electron shell than B3+: the 2s electron in C3+ is further from the nucleus and more shielded than the 1s electron in B3+.[1]
Despite the greater nuclear charge of C3+, the electrostatic attraction between the nucleus and its 2s electron is weaker. Less energy is required to remove the 2s electron from C3+ than the 1s electron from B3+, so B has the higher fourth ionisation energy.[1]