Cambridge IGCSE · Chemistry 0620
IGCSE Chemistry: Atoms, elements and compounds — Practice Questions & Answers
How matter is built from atoms, how sub-atomic particles define elements and isotopes, and how ionic, covalent and metallic bonds form.
1436 practice questions available for this topic — here are 10 with full answers and explanations.
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Practice questions with answers
1
Multiple choice · Easy
Which statement best describes an element?
- A substance containing only one type of atom
- A substance containing two or more elements chemically joined
- Two or more substances mixed but not chemically joined
- A substance that can be separated by filtration
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WhyAn element is a substance made of only one type of atom and cannot be broken down into anything simpler by chemical means.
2
Multiple choice · Easy
Which of these is a mixture?
- Air
- Water
- Carbon dioxide
- Sodium chloride
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WhyAir is a mixture of gases (mainly nitrogen and oxygen) that are not chemically combined and can be separated physically.
3
Multiple choice · Easy
What is the relative charge of a proton?
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WhyA proton carries a relative charge of +1, an electron -1, and a neutron has no charge.
4
Multiple choice · Easy
Where are protons and neutrons found in an atom?
- In the nucleus
- In the electron shells
- Outside the atom
- Spread evenly throughout the atom
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WhyProtons and neutrons are located in the central nucleus, while electrons occupy shells around the nucleus.
5
Fill in the blank · Easy
An atom of oxygen has a proton number of 8, so it contains electrons when neutral.
Answer:
8 / eight
WhyA neutral atom has equal numbers of protons and electrons, so oxygen has 8 electrons.
6
Fill in the blank · Easy
The number of protons in an atom is called its number.
Answer:
proton / atomic
WhyThe proton number (also called atomic number) identifies the element and equals the number of protons.
7
Multiple choice · Medium
An atom has a nucleon number of 23 and a proton number of 11. How many neutrons does it have?
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WhyNumber of neutrons = nucleon number - proton number = 23 - 11 = 12.
8
Multiple choice · Medium
What is the electronic configuration of a magnesium atom (proton number 12)?
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WhyTwelve electrons fill the shells in the order 2, then 8, then 2, giving 2,8,2.
9
Multiple choice · Medium
Which pair are isotopes of each other?
- An atom with 6 protons and 6 neutrons, and an atom with 6 protons and 8 neutrons
- An atom with 6 protons and 6 neutrons, and an atom with 7 protons and 7 neutrons
- An atom with 6 protons and 8 neutrons, and an atom with 8 protons and 6 neutrons
- An atom with 7 protons and 6 neutrons, and an atom with 8 protons and 8 neutrons
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WhyIsotopes have the same proton number but different nucleon numbers; both atoms here have 6 protons but different neutron counts.
10
Multiple choice · Medium
In which type of bonding are electrons transferred from a metal atom to a non-metal atom?
- Ionic bonding
- Covalent bonding
- Metallic bonding
- Intermolecular bonding
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WhyIonic bonding involves transfer of electrons from a metal to a non-metal, forming oppositely charged ions.
Key terms in Atoms, elements and compounds
Atom: The smallest particle of an element that still has the chemical properties of that element.
Element: A pure substance made of only one type of atom that cannot be broken down into simpler substances by chemical means.
Compound: A pure substance formed when two or more different elements are chemically combined in fixed proportions.
Mixture: Two or more substances physically combined together that are not chemically bonded and can be separated by physical methods.
Molecule: A group of two or more atoms held together by covalent bonds.
Pure substance: A material consisting of only one element or one compound with nothing else mixed in.
Proton: A positively charged subatomic particle found in the nucleus with a relative mass of one.
Neutron: A subatomic particle with no charge found in the nucleus with a relative mass of one.
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