Use a copy of the Periodic Table where you need one.
What type of bonding holds magnesium and oxygen together in magnesium oxide?
Source: Learners' Alley, Chemical Bonding and Materials slides
Which substance conducts electricity in the solid state?
Source: Learners' Alley, Chemical Bonding and Materials slides
Why is diamond very hard?
Source: Learners' Alley, Chemical Bonding and Materials slides
How many pairs of electrons are shared between the two atoms in an oxygen molecule, O2?
Source: Learners' Alley, Chemical Bonding and Materials slides
A sodium atom has the electronic configuration 2.8.1 and a chlorine atom has the electronic configuration 2.8.7. They react to form sodium chloride.
Source: Learners' Alley, Chemical Bonding and Materials slides
Which of the following pairs of elements forms covalent bonds?
Source: 2023 GESS Sec 3 End-of-Year P1 Q13
Which of the following correctly describes metallic bonding?
Source: 2023 GESS Sec 3 End-of-Year P1 Q14
Copper is used in electrical wiring to conduct electricity. Why is copper able to conduct electricity?
Source: 2022 XMS Sec 3 WA2 Q1
Calcium phosphate is the main mineral found in human bones and teeth. What is the chemical formula of calcium phosphate?
Source: 2022 XMS Sec 3 WA2 Q2
A solid substance was found to be unable to conduct electricity. When pure water was used to dissolve the substance, the solution could conduct electricity. What could be the structure of the substance, and why can the solution conduct electricity?
| structure | reason for being able to conduct electricity | |
|---|---|---|
| A | giant metallic structure | Water can conduct electricity. |
| B | giant metallic structure | It has free-moving electrons. |
| C | giant ionic structure | It has free-moving ions. |
| D | giant ionic structure | Water can conduct electricity. |
Source: 2022 XMS Sec 3 WA2 Q4
Which of the following groups consists of a metallic element, an ionic compound and a gaseous mixture?
Source: 2020 XMS Sec 3 WA1 P1 Q3
Which diagram represents a chemical change?
Source: 2024 CHS Sec 3 End-of-Year Section A Q4
The diagram shows the structure of an alloy.
Which statement about alloys is correct?
Source: Broadrick Sec 4 Prelim P1 Q32
Use this list of substances to answer the questions: sulfur dioxide, graphite, oxygen, sodium sulfate, dry ice.
Source: 2022 XMS Sec 3 WA2 B1, adapted
Scandium is a metallic element with the symbol Sc and atomic number 21.
Source: 2023 XMS Sec 3 WA2 Q7
The table shows some information about the properties of compounds Li2O and CH4.
| compound | melting point / °C | boiling point / °C | solubility in water | electrical conductivity at room temperature and pressure |
|---|---|---|---|---|
| Li2O | 1438 | 2600 | soluble | poor |
| CH4 | −182 | −162 | insoluble | poor |
Source: 2023 XMS Sec 3 WA2 Q10
Bionic bonding[1]
Magnesium is a metal and oxygen is a non-metal. Magnesium loses 2 electrons and oxygen gains them, so ions form and attract each other.
Bgraphite[1]
Each carbon atom in graphite uses only 3 of its 4 outer electrons, so one electron per atom is free to move.
BEach carbon atom is bonded to four others by strong covalent bonds.[1]
A large amount of energy is needed to break the many strong covalent bonds in the giant network.
B2[1]
Each oxygen atom has 6 outer electrons and shares 2 of them. This makes a double bond, which is two shared pairs.
A sodium atom loses 1 electron to form a sodium ion, Na+. [1]
A chlorine atom gains 1 electron to form a chloride ion, Cl−. [1]
Ionic bond. [1]
It is the electrostatic attraction between the oppositely charged ions. [1]
Bphosphorus and oxygen[1]
Covalent bonds form between non-metals. Phosphorus and oxygen are both non-metals. The other pairs are a metal and a non-metal, which form ionic bonds.
Aelectrostatic forces of attraction between positive metal ions surrounded by a ‘sea of delocalised electrons’[1]
Metal atoms lose their outer electrons to form positive ions. The attraction between oppositely charged particles is electrostatic.
ACopper has a ‘sea’ of delocalised electrons.[1]
The delocalised electrons are mobile charge carriers. The positive ions stay in fixed positions.
DCa3(PO4)2[1]
Calcium forms Ca2+ and phosphate is PO43−. Three Ca2+ (+6) balance two PO43− (−6).
Cgiant ionic structure, because it has free-moving ions[1]
The ions are fixed in the solid but move freely when dissolved.
Bair, tungsten, sodium bromide[1]
Tungsten is a metallic element, sodium bromide is an ionic compound and air is a gaseous mixture. The order in the list does not matter.
DD[1]
In D, atoms of two different elements join to form particles of a new compound, so a new substance is made.
CIn an alloy there is attraction between positive ions and a ‘sea of delocalised electrons’.[1]
An alloy still has metallic bonding. It can contain a non-metal, as steel contains carbon, and it is a mixture, so brass has no chemical formula.
Sodium sulfate [1]
Graphite [1]
Sulfur dioxide and sodium sulfate [1]
Both contain sulfur and oxygen.
Dry ice [1]
Graphite [1]
Any one: dry ice, CO2 or sulfur dioxide, SO2 or sodium sulfate, Na2SO4. [1]
Correct number of electrons: a nitrogen atom with 3 shared pairs and 1 lone pair, and each hydrogen atom with 1 shared pair. [1]
Correct number of atoms: one nitrogen atom bonded to three hydrogen atoms. [1]
A giant metallic structure, a lattice of positive ions [1]
in a sea of delocalised electrons. [1]
Sc2(SO4)3 [1]
Sc2O3 shows that scandium forms Sc3+ and sulfate is SO42−.
Sc(OH)3 [1]
The correct ratio of two Li+ ions to one O2− ion. [1]
Each ion shown with its charge: Li+ with no outer electrons and O2− with 8 outer electrons, in square brackets. [1]
Li2O: solid [1]
CH4: gas [1]
Li2O has a giant ionic lattice. [1]
As a solid, the ions are held in fixed positions and cannot move freely to conduct electricity. [1]
CH4 consists of simple molecules. [1]
The weak intermolecular forces of attraction need little energy to overcome, so the melting and boiling points are low. [1]