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Science 7–10 · Year 10

Lithium and sodium in water: reactivity down group 1

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Teacher-led demonstrationPracticalHigh risk

Teacher-led demonstration

A teacher carries out this activity as a demonstration. Its materials, steps, variables, misconceptions and sources are not published on the open web, and neither is any result, control or note that states a number or an amount: tutors and administrators read them on the learning platform, with the safety card first. The idea, the hazards and the curriculum references are below.

Open the procedure on the learning platform (tutor or administrator sign-in)

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

The idea

Elements in the same group react in the same way and their reactivity changes in a regular order down the group, which the periodic table was built to show.

Safety card

High riskTeacher-led demonstration

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

  • sodium reacts violently with water; hydrogen can ignite or pop if it accumulates
  • molten sodium and corrosive hydroxide can spit
  • lithium and sodium are corrosive and highly flammable

Controls

At least one of them states a number or an amount, which may be part of the method, so the controls are shown with the method to tutors and administrators on the learning platform.

Note

It states a number or an amount, which may be part of the method, so it is shown with the method to tutors and administrators on the learning platform.

What you should see

Lithium floats, fizzes steadily and shrinks away without catching fire; the indicator turns blue-purple around it (alkaline). Sodium melts into a ball, skates across the surface, fizzes vigorously and may burn with a yellow flame and white smoke; the indicator turns purple faster. The learner knows it worked when the sodium is clearly more vigorous than the lithium and the prediction for potassium (faster still, lilac flame) follows from the pattern.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

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