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Researching the topic

After the scientific question has been decided upon, the next step in the scientific method is to research the topic.

This improves your understanding of the science behind your question, and helps to prepare you for the next step in the scientific method: making predictions.

You can collect information from textbooks, the internet and even your own experiences.

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Introducing predictions

After you have finished researching your topic, the next step in the scientific method is to make a prediction.

A prediction is a statement that says what you think the outcome of your investigation will be.

For example:

I predict that my cup of tea will get cold faster if I place it in the fridge

rather than on the kitchen table.

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How do you make a prediction?

It is important to use scientific facts to make your predictions.

A prediction made without scientific facts is really just a guess!

You will need to use the information from the research stage of your investigation to come up with your prediction.

Predictions are important because they are tested during scientific experiments.

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Predicting trends in group 1 metals

What would you need to know to make a prediction for this question?

How will the elements sodium and caesium react with water?

The research stage of your investigation should provide some background information about sodium and caesium.

Their position in the periodic table would be particularly useful, as it would highlight any elements that might have similar properties to sodium and caesium.

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Sodium and caesium

Sodium (Na) and caesium (Cs) are alkali metals. They are located in group 1 of the periodic table.

All alkali metals react with water in a similar way. If we can find out how other alkali metals react with water, we can make a prediction for the reactions of sodium and caesium.

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Lithium, potassium and rubidium

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Spotting trends in results

Can you spot a trend in the results?

The further down group 1 an element is located, the more reactive it is. Of the elements shown, lithium is the least reactive and rubidium is the most reactive.

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Predicting a reaction for sodium (1)

How can we use the results to predict the reaction for sodium?

Sodium is located beneath lithium and above potassium. We can predict that sodium will be more reactive than lithium but less reactive than potassium.

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Predicting a reaction for sodium (2)

We can even predict what we might observe when sodium reacts with water.

As sodium is likely to be between lithium and potassium in reactivity, we can predict that it will disappear more quickly than lithium but more slowly than potassium. Sodium might be expected to fizz more than lithium, and move around more quickly.

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Prediction summary

Using existing scientific facts, we have been able to develop the following predictions for sodium:

Sodium will be more reactive than lithium but less reactive than potassium.

Sodium will disappear more quickly than lithium but less quickly than potassium. It will fizz more than lithium, and move around more quickly.

What is the next stage of the scientific method?

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Predicting a reaction for caesium activity

Can you predict the reaction of caesium with water?