Use a copy of the Periodic Table where you need one.
Which statement about atoms of chlorine-35 and chlorine-37 is correct?
Source: Learners' Alley, Atomic Structure slides
Calcium has proton number 20. What is its electronic configuration?
Source: Learners' Alley, Atomic Structure slides
Complete the table. The first row is done for you.
| particle | protons | neutrons | electrons |
|---|---|---|---|
| 18474W | 74 | 110 | 74 |
| an atom of uranium-235 (proton number 92) | |||
| a sodium ion with a charge of +1 (a sodium atom has 11 protons and 12 neutrons) | |||
| 3216S2− |
Source: Learners' Alley, Atomic Structure slides
Boron-11 is the most common isotope of boron. Boron has proton number 5.
Source: Learners' Alley, Atomic Structure slides
ChallengeArsenic is a toxic element with proton number 33. Arsenic and its compounds react in the same way as phosphorus and its compounds. Phosphorus has proton number 15. Arsenic has 5 valence electrons.
Source: Learners' Alley, Atomic Structure slides
Which option correctly describes the locations of the sub-atomic particles in an atom?
| proton | neutron | electron | |
|---|---|---|---|
| A | in the nucleus | in the nucleus | orbiting the nucleus |
| B | in the nucleus | in the nucleus | in the nucleus |
| C | orbiting the nucleus | in the nucleus | orbiting the nucleus |
| D | orbiting the nucleus | orbiting the nucleus | in the nucleus |
Source: 2023 GESS Sec 3 End-of-Year P1 Q8
Which statement about an atom is true?
Source: 2023 HYSS Sec 3 End-of-Year P1 Q6
In which of the following sets do all the particles have the same number of electrons?
Source: 2023 GESS Sec 3 End-of-Year P1 Q11
Chlorine-37 is an isotope of chlorine.
| particle | number | name of particle |
|---|---|---|
| X | 20 | |
| Y | 18 | |
| Z | 17 |
| particle | number |
|---|---|
| X | |
| Y | |
| Z |
Source: BLSS 2024 Sec 4 Prelim P2 Q3, adapted
| relative mass | relative charge | |
|---|---|---|
| proton | ||
| neutron | ||
| electron |
The symbol of an atom of aluminium is 2713Al.
Source: 2023 GESS Sec 3 End-of-Year P2 Q5
Flerovium, Fl, has proton number 114. It was first made in research laboratories in 1998. Two isotopes of flerovium are 286Fl and 289Fl.
| isotope | protons | neutrons | electrons |
|---|---|---|---|
| 286Fl | |||
| 289Fl |
Source: CHS Sec 3 End-of-Year Section B Q5(b)
Table 12.1 shows information about two atoms. Complete Table 12.1.
| atom | protons | neutrons | electrons |
|---|---|---|---|
| 3919K | |||
| 28 | 24 |
Source: 2025 TKGS Sec 4 Prelim P2 Q2(a)
CThey have the same number of electrons.[1]
D2.8.8.2[1]
Uranium-235: 92 protons, 143 neutrons (235 − 92) and 92 electrons[1]
Sodium ion: 11 protons, 12 neutrons and 10 electrons (11 − 1)[1]
Sulfide ion: 16 protons, 16 neutrons (32 − 16) and 18 electrons (16 + 2)[1]
5 protons, 6 neutrons (11 − 5) and 5 electrons[1]
2.3[1]
Phosphorus has the electronic configuration 2.8.5, so it also has 5 valence electrons.[1]
Elements with the same number of valence electrons have similar chemical properties.[1]
Aproton in the nucleus, neutron in the nucleus, electron orbiting the nucleus[1]
Protons and neutrons are found in the nucleus of an atom while electrons are found in the electron shells around the nucleus.
BThe proton number of all atoms of an element is the same.[1]
CK+, Ca2+, P3−[1]
Isotopes are atoms of the same element with the same number of protons[1] but different numbers of neutrons.[1]
| particle | number | name of particle |
|---|---|---|
| X | 20 | neutron |
| Y | 18 | electron |
| Z | 17 | proton |
All three correct[2] (two correct earns 1 mark).
| particle | number |
|---|---|
| X (neutrons) | 18 |
| Y (electrons) | 17 |
| Z (protons) | 17 |
All three correct[2] (two correct earns 1 mark).
| relative mass | relative charge | |
|---|---|---|
| proton | 1 | +1 |
| neutron | 1 | 0 |
| electron | 1/1836 or 1/1840 | −1 |
Three blanks correct[1] and the other three blanks correct[1]
27 − 13 = 14[1]
2.8.3[1]
They are isotopes. They are atoms of the same element with the same proton number (13) but different numbers of neutrons (14 and 13).[1]
Atoms of the same element with the same number of protons but different numbers of neutrons.[1]
| isotope | protons | neutrons | electrons |
|---|---|---|---|
| 286Fl | 114 | 172 | 114 |
| 289Fl | 114 | 175 | 114 |
Each correct row[1][1]
| atom | protons | neutrons | electrons |
|---|---|---|---|
| 3919K | 19 | 20 | 19 |
| 5224Cr | 24 | 28 | 24 |
Each correct row[1][1]
The atom is neutral, so protons = electrons = 24, which is chromium, and the nucleon number is 24 + 28 = 52.