What charge do Group 1 ions have?

1+, formed by losing the outer electron.

Name three physical properties of the alkali metals.

Soft, low density and low melting point (for metals).

Why do lithium, sodium and potassium float on water?

They have a lower density than water.

What is the trend in reactivity down Group 1?

Reactivity increases down the group.

Why is potassium more reactive than sodium?

Its outer electron is further from the nucleus with more shielding, so it is held less tightly and lost more easily.

What are the products when an alkali metal reacts with water?

A metal hydroxide and hydrogen gas.

What colour does universal indicator turn in the solution from an alkali metal and water?

Purple, because the hydroxide solution is alkaline.

What do you see when potassium is added to water?

It floats, melts, moves very quickly and burns with a lilac flame.

Why are alkali metals stored under oil?

To stop them reacting with oxygen and water vapour in the air.

Group 1: the alkali metalsIB MYP Chemistry: Flashcards

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How many electrons are in the outer shell of a Group 1 atom?

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How many electrons are in the outer shell of a Group 1 atom?: One.
What charge do Group 1 ions have?: 1+, formed by losing the outer electron.
Name three physical properties of the alkali metals.: Soft, low density and low melting point (for metals).
Why do lithium, sodium and potassium float on water?: They have a lower density than water.
What is the trend in reactivity down Group 1?: Reactivity increases down the group.
Why is potassium more reactive than sodium?: Its outer electron is further from the nucleus with more shielding, so it is held less tightly and lost more easily.
What are the products when an alkali metal reacts with water?: A metal hydroxide and hydrogen gas.
Write the balanced equation for sodium and water.: 2Na + 2H₂O → 2NaOH + H₂
What colour does universal indicator turn in the solution from an alkali metal and water?: Purple, because the hydroxide solution is alkaline.
What do you see when potassium is added to water?: It floats, melts, moves very quickly and burns with a lilac flame.
Write the equation for lithium and oxygen.: 4Li + O₂ → 2Li₂O
Why are alkali metals stored under oil?: To stop them reacting with oxygen and water vapour in the air.

Exam questions on Group 1: the alkali metals

A school technician in Singapore is preparing a demonstration for a Year 9 class. A small piece of sodium is taken from a bottle of oil, cut with a knife, dried and dropped into a large trough of water containing a few drops of universal indicator. The class will watch from behind a safety screen.
Write the word equation for the reaction of sodium with water.2 marks
A teacher drops equal-sized small pieces of lithium, sodium and potassium into three separate troughs of water. Lithium floats and fizzes steadily until it disappears. Sodium floats, melts into a silvery ball and fizzes rapidly, darting across the surface. Potassium floats, melts, darts about very quickly and burns with a lilac flame.
Explain, in terms of electrons, why potassium is more reactive than sodium.2 marks
A student wants to compare the reactivity of lithium, sodium and potassium. She plans to add a small piece of each metal, one at a time, to a large beaker of water at room temperature and to time how long each piece takes to stop fizzing. Her teacher will cut and dry each piece for her.
State a testable hypothesis for her investigation, with a scientific reason, and identify the independent variable.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).