Starter quiz
- What is an ion?
- an atom that has gained extra electrons ✓
- an atom that has lost some electrons ✓
- an atom that has gained extra protons
- an atom with extra neutrons
- an atom that has lost some protons
-
- When metal atoms react to form ions they ...
- lose electrons. ✓
- gain electrons.
- form positive ions. ✓
- form negative ions.
- become a noble gas.
-
- Which of the following elements form negatively charged ions?
- chlorine ✓
- magnesium
- sodium
- oxygen ✓
- neon
-
- How does a sodium atom become a sodium ion (Na⁺)?
- it gains one electron
- it loses one electron ✓
- it gains one proton
- it loses a proton
- it gains a neutron
-
- What is the total charge of an ionic compound?
- +1
- +2
- 0 ✓
- -1
- -2
-
- What is electrolysis?
- a process of using electricity to break down ionic compounds into their elements ✓
- a process of using heat to break down ionic compounds into their elements
- a process of using pressure to break down ionic compounds into their elements
- a process of using electricity to break down molecules into their elements
- a process of using heat to break down molecules into their elements
-
Exit quiz
- What happens when molten calcium chloride is electrolysed?
- the Cl- ion is attracted to the anode ✓
- the Cl- is attracted to the cathode
- the Ca2+ is attracted to the anode
- the Ca2+ is attracted to the cathode ✓
-
- What state must salts be in to conduct electricity for electrolysis?
- gaseous
- molten ✓
- dissolved ✓
- solid
-
- What is produced at the cathode during the electrolysis of molten sodium chloride?
- chlorine gas
- sodium chloride
- sodium metal ✓
-
- Why can molten salts conduct electricity?
- the atoms are free to move
- the electrons are free to move
- the ions are free to move ✓
-
- What happens to cations during electrolysis?
- they gain electrons ✓
- they lose electrons
- they remain unchanged
- they gain protons
- they lose protons
-
- What is the overall charge of the products formed during electrolysis?
- +1
- -1
- 0 ✓
- +2
- -2
-
Worksheet
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Lesson Details
Key learning points
- A solid ionic compound cannot conduct electricity.
- Salts are ionic compounds which can be electrolysed when they are in the molten state.
- Gases may be formed at the electrodes.
- Freely moving ions can reach the electrodes and undergo oxidation or reduction.
- A non-metal always forms at the positive electrode, and a metal forms at the negative electrode.
Common misconception
Pupils often think that, during electrolysis, the charge carriers are electrons and not ions.
Revisit the structure of ionic compounds in the solid and liquid states. Point out that there are no delocalised electrons. The electrons are associated with ions and so are unable to move through the electrolyte. Ions can move in the liquid state.
Keywords
Molten - the term used to describe a liquid substance formed by heating ionic compounds and metal ores.
Anode - A positively charged electrode, in an electrolysis cell, to which the anions are attracted.
Cathode - A negatively charged electrode, in an electrolysis cell, to which the cations are attracted.
Anion - A negatively charged ion.
Cation - A positively charged ion.
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