Activity 4. Prediction of unknown elements
Imagine you are a scientist like Dmitri Mendeleev. Your task is to “predict” the properties of an unknown chemical element based on its place in the periodic table.

Source: https://depositphotos.com
Select a blank space in the table (for example, below an existing element or between two known elements). This will be your “unknown element”.
- Use the periodic law to predict:
- The atomic number of the element.
- Its atomic mass (approximately).
- Its chemical properties (activity, valence).
- Its physical properties (state at room temperature, colour, density).
- Describe how this item could be used in practice – in industry, medicine or technology, based on similar items in the table. Use electronic resources (e.g., WebElements or Wikipedia) to reference for similar items. Then make an assumption:
- How can it be useful in the industry?
- What medical applications can it have?
- Can it be used in technology?
- Submit your “predictions” in the electronic format of your choice:
Presentations (PowerPoint/Google Slides):
- Create a short presentation to include:
- Atomic number, mass and properties of the selected predicted element;
- Comparison with similar elements in the periodic table;
- Possible applications in industry and technology;
- Pictures or diagrams associated with the item.
Spreadsheets (Excel/Google Sheets):
- Create a data table for the predicted chemical element to include:
- Atomic and chemical properties of the element;
- Comparison with neighbouring elements;
- Summary of results and “predictions”;
- May contain formulas or graphs to compare properties.
Sample hint:
If your element is in group 1 (alkali metals) and is between potassium and rubidium, it is likely to be a soft metal with high reactivity and will react strongly with water. It can also be used in batteries, like sodium and lithium.

You can access the interactive periodic table at:
https://ptable.com – interactive and detailed version
https://www.webelements.com – offers additional information about the elements

