Atoms, elements and compounds — IGCSE Chemistry (0620) questions by topic
Defining isotopes precisely, distinguishing a compound from a mixture, judging which statements about isotopes are chemically correct, and working out the electron, neutron and proton count for a specific isotope of boron are the core tasks in this topic, worth 1 to 21 marks across 51 real questions from 2023 to 2025 papers.
State, identify, complete, calculate and deduce are the top command words, and deduce specifically means working from proton number and mass number to the correct particle counts, showing that the reasoning follows the given data. Because a single miscounted proton or neutron invalidates the whole answer, working through these calculations and checking each against instant marking is a precise way to catch that error immediately rather than repeating it across a set of isotopes.
May–June 2025, Paper 11
An atom of element Q contains 19 electrons, 19 protons and 20 neutrons. What is Q? A calcium B potassium C strontium D yttrium
Answer this question and get it marked →Which part of an atom has a relative mass of 1 and a relative charge of 0? A electron B neutron C nucleus D proton
Answer this question and get it marked →Which row identifies the number of electrons, neutrons and protons in a particle which is an isotope of B-11 (proton number 5)? electrons neutrons protons --- --- --- --- A 5 5 5…
Answer this question and get it marked →May–June 2025, Paper 12
Which substance is a mixture of one element and one compound? A aqueous glucose B clean, dry air C oxygen dissolved in distilled water D stainless steel
Answer this question and get it marked →What is different for isotopes of the same element? A nucleon number B number of electron shells C number of electrons in the outer electron shell D proton number
Answer this question and get it marked →May–June 2025, Paper 13
Which diagram shows a mixture of an element and a compound? Each option (A, B, C, D) shows a box containing particles drawn as circles, where open (white) circles represent atoms…
Answer this question and get it marked →An atom of the element erbium is represented by 167/68 Er (mass number 167, proton number 68). Which row shows the number of protons, neutrons and electrons in this atom? protons…
Answer this question and get it marked →May–June 2025, Paper 21
Which atom has an equal number of protons, neutrons and electrons? A. ⁴⁰Ar (argon) B. ¹H (hydrogen) C. ²³Na (sodium) D. ¹⁴N (nitrogen)
Answer this question and get it marked →May–June 2025, Paper 22
Which row gives the number of protons, electrons and neutrons in an atom of zinc? protons electrons neutrons --- --- --- --- A 30 30 35 B 30 35 35 C 35 30 30 D 35 35 30
Answer this question and get it marked →Which particles have the electronic configuration 2,8,8? 1 an argon atom, Ar 2 an aluminium ion, Al^3+ 3 a sodium ion, Na^+ 4 a chloride ion, Cl^- A 1 and 3 B 1 and 4 C 2 and 3 D…
Answer this question and get it marked →A sample of element Q has two isotopes. Their relative masses and abundances are shown. relative mass of isotope abundance / % --- --- 238 66 244 34 What is the relative atomic…
Answer this question and get it marked →May–June 2025, Paper 31
A list of substances is shown: aluminium, ammonia, argon, bromine, carbon dioxide, fluorine, iron, magnesium, magnesium chloride, nitrogen, oxygen, potassium. Each substance may…
Answer this question and get it marked →May–June 2025, Paper 41
Atoms are made of electrons, neutrons and protons. Complete Table 2.1 to show the relative charge and relative mass of each particle. Table 2.1 particle relative charge relative…
Answer this question and get it marked →May–June 2025, Paper 43
Atoms are made of electrons, neutrons and protons. State which of these particles are found in the nucleus of an atom.
Answer this question and get it marked →May–June 2024, Paper 11
The diagram shows some properties of particles in an atom, with regions labelled A, B, C and D arranged around descriptions: "found outside nucleus", "relative mass less than 1"…
Answer this question and get it marked →May–June 2024, Paper 12
Which statement is correct? A Air is a mixture of gaseous elements only. B Alloys are formed when a metal is ionically bonded to other elements. C Carbon dioxide is a mixture of…
Answer this question and get it marked →Which row shows the number of protons, neutrons and electrons in the ion shown (an oxide ion, ¹⁸O²⁻ with mass number 18, atomic number 8)? (columns: protons; neutrons; electrons)…
Answer this question and get it marked →Isotopes of the same element have some features that are the same and some that are different. Which row shows the features that are the same (✓) and those that are different (✗)?…
Answer this question and get it marked →May–June 2024, Paper 13
Four substances in a mixture are listed: calcium nitrate; iron(II) sulfate; oxygen; water. Which statement describes the mixture? A It contains 6 elements. B It contains 3…
Answer this question and get it marked →An ion is represented by the symbol shown (an oxide ion ¹⁸O²⁻, mass number 18, atomic number 8, charge 2-). Which statements about this ion are correct? 1 The ion contains 8…
Answer this question and get it marked →What is the meaning of the term nucleon number? A the number of neutrons in the nucleus of an atom B the number of protons in the nucleus of an atom C the total number of protons…
Answer this question and get it marked →May–June 2024, Paper 21
Four statements about atoms are listed: 1 The centre of an atom is positively charged. 2 Protons and electrons are located in the nucleus. 3 Protons and electrons have the same…
Answer this question and get it marked →Which statement explains why isotopes of the same element have the same chemical properties? A They have different numbers of protons in their nucleus. B They have different…
Answer this question and get it marked →May–June 2024, Paper 22
Which statements about isotopes are correct? 1 Isotopes are atoms of different elements with the same number of protons. 2 Isotopes of the same element have the same chemical…
Answer this question and get it marked →May–June 2024, Paper 23
Substances P and Q both conduct electricity. P is a mixture of two different types of atom. Q is made of only one type of atom. Which row describes P and Q? (columns: P; Q) A…
Answer this question and get it marked →An atom of element R contains 15 protons, 16 neutrons and 15 electrons. What is R? A gallium B phosphorus C sulfur D zinc
Answer this question and get it marked →May–June 2024, Paper 31
An atom of carbon is represented by the symbol ¹⁴₆C (mass number 14, atomic number 6). Describe this atom of carbon in terms of: the position of the electrons, neutrons and…
Answer this question and get it marked →May–June 2024, Paper 32
An atom of sulfur is represented by the symbol ³⁴₁₆S (mass number 34, atomic number 16). Describe this atom of sulfur in terms of: the position of the electrons, neutrons and…
Answer this question and get it marked →May–June 2024, Paper 33
An atom of phosphorus is represented by the symbol ³¹₁₅P (mass number 31, atomic number 15). Describe this atom of phosphorus in terms of: the position of the electrons, neutrons…
Answer this question and get it marked →May–June 2024, Paper 41
Complete Table 2.1 (atom or ion; number of protons; number of electrons; number of neutrons): atom or ion protons electrons neutrons ------ ------ ------ ------ ³⁷₁₇Cl⁻ 17 ⁶³₂₉Cu⁺…
Answer this question and get it marked →May–June 2024, Paper 42
Sulfur is a Group VI element. A sample of sulfur contains two isotopes, ³²S and ³⁴S. Complete Table 5.1 to show the number of protons and neutrons in one atom of each isotope of…
Answer this question and get it marked →May–June 2024, Paper 43
Complete Table 2.1 (atom or ion; number of protons; number of electrons; number of neutrons): atom or ion protons electrons neutrons ------ ------ ------ ------ ⁶³₂₉Cu 29 ³⁷₁₇Cl⁻…
Answer this question and get it marked →October–November 2024, Paper 11
One atom of an element contains 12 electrons, 12 protons and 13 neutrons. How many nucleons does this atom contain? A 12 B 13 C 24 D 25
Answer this question and get it marked →A diagram representing a mixture of four particles is shown (the diagram shows particles, some made of two joined identical atoms and some single atoms, of more than one kind).…
Answer this question and get it marked →October–November 2024, Paper 12
Three boxes P, Q and R each show a diagram of particles. Which statement about the boxes P, Q and R is correct? A Box P contains two compounds, and box R contains two elements. B…
Answer this question and get it marked →Which information about an element is given by its atomic number? A the number of protons in the nucleus of an atom of an element B the number of particles in the nucleus of an…
Answer this question and get it marked →The symbols represent four atoms (the letters used are not the usual atomic symbols): W has nucleon number 40 and proton number 20; X has nucleon number 40 and proton number 19; Y…
Answer this question and get it marked →October–November 2024, Paper 13
What is the nucleon number of an atom? A the number of neutrons B the number of protons C the total number of protons and neutrons D the total number of protons and electrons
Answer this question and get it marked →An atom has three electron shells. There are three electrons in the outer shell. How many protons and how many neutrons are in this atom? protons neutrons --- --- --- A 13 14 B 13…
Answer this question and get it marked →October–November 2024, Paper 21
Which diagram represents one helium atom? (Four atom diagrams A-D are shown with a key: proton, neutron, electron. The correct diagram has 2 protons and 2 neutrons in the nucleus…
Answer this question and get it marked →October–November 2024, Paper 22
Rubidium has two isotopes, 85/37 Rb and 87/37 Rb. Which statement explains why both isotopes have the same chemical properties? A They have the same number of protons. B They have…
Answer this question and get it marked →October–November 2024, Paper 41
This question is about atomic structure and the Periodic Table. Define the term nucleon number.
Answer this question and get it marked →May–June 2023, Paper 31
This question is about sulfur and compounds of sulfur. Sulfur has several isotopes. Define the term isotopes.
Answer this question and get it marked →May–June 2023, Paper 33
This question is about bromine and compounds of bromine. Deduce the number of protons, neutrons and electrons in the bromide ion shown. ⁸¹₃₅Br⁻ number of protons ... number of…
Answer this question and get it marked →Fig. 7.1 shows the displayed formula of compound E (containing a C=C double bond, a -CH₃ group and an -OH group). On Fig. 7.1 draw a circle around the functional group that makes…
Answer this question and get it marked →October–November 2023, Paper 32
Petroleum is a mixture of hydrocarbons. Describe two characteristics of a mixture.
Answer this question and get it marked →October–November 2023, Paper 33
Hydrocarbons are compounds of carbon and hydrogen. State the meaning of the term compound.
Answer this question and get it marked →October–November 2023, Paper 41
Boron and aluminium are Group III elements. Boron has only two naturally occurring isotopes, ¹⁰B and ¹¹B. Complete Table 2.1 to show the numbers of protons, neutrons and electrons…
Answer this question and get it marked →October–November 2023, Paper 42
Table 1.1 gives the electronic configurations of some atoms and ions, A to G (A = 2,5; B = 2,8; C = 2,8,2; D = 2,8,4; E = 2,8,5; F = 2,8,6; G = 2,8,18,7). Answer the following…
Answer this question and get it marked →Cobalt and copper are transition elements. Copper has two naturally occurring isotopes, ⁶³Cu and ⁶⁵Cu. Cobalt has only one naturally occurring isotope, ⁵⁹Co. Complete Table 2.1 to…
Answer this question and get it marked →October–November 2023, Paper 43
Table 2.1 gives information about particles A, B, C, D, E and F (electrons, neutrons, protons): A (5,6,5), B (10,11,10), C (10,14,13), D (18,17,16), E (18,17,17), F (15,16,15).…
Answer this question and get it marked →Other IGCSE Chemistry topics
- Organic chemistry (155)
- The Periodic Table (102)
- Metals (96)
- Acids, bases and salts (84)
- Experimental techniques and chemical analysis (84)
- Chemical reactions (80)
- Stoichiometry (62)
- Chemical bonding (58)
- Chemistry of the environment (55)
- Electrochemistry (47)
- Practical skills (43)
- States of matter (42)