FOCUS ON: The Early Periodic Table

Part 1 - Keywords:

1. Mendeleev

2. Periodic Table

3. Atomic Weights

4. Relative Atomic Mass

5. Elements

6. Properties

7. Compounds

8. Predictions

9. Eka-silicon

10. Germanium

Part 2 - Key Facts:

Early Attempts to Classify Elements: Before the discovery of protons, neutrons, and electrons, scientists attempted to classify elements by arranging them based on their atomic weights, now known as relative atomic mass. These early periodic tables were incomplete due to undiscovered elements, and some elements were placed in groups that did not reflect their similarities.

Dmitri Mendeleev:

• Russian chemist Dmitri Mendeleev published his first periodic table in 1869, organizing elements by increasing atomic weights.

• Mendeleev considered both the properties of elements and their compounds, resulting in a table with gaps and elements with similar properties grouped together.

• Despite the atomic weight ordering, some adjacent elements were in the wrong order.

Predictions Using Gaps:

• Mendeleev left gaps in his table for unknown elements, predicting their properties by examining the elements around the gaps.

• An example is 'eka-silicon,' a predicted element below silicon. Subsequently, germanium was discovered, confirming Mendeleev's predictions as its properties matched the anticipated ones.

Part 3 - Quick Quiz:

1. What did Mendeleev use to arrange elements in his periodic table?

   a) Atomic numbers

   b) Atomic weights (relative atomic mass)

   c) Number of electrons

   Answer: b) Atomic weights (relative atomic mass)

2. What feature did Mendeleev's periodic table have, which later led to the discovery of new elements?

   a) Filled with known elements

   b) Gaps for undiscovered elements

   c) Arranged by alphabetical order

   Answer: b) Gaps for undiscovered elements

3. How did Mendeleev predict the properties of undiscovered elements?

   a) By random guesswork

   b) By looking at the properties of elements next to the gaps

   c) By analysing the alphabetical order

   Answer: b) By looking at the properties of elements next to the gaps

Part 4 - Going Further:

Question: Explain Mendeleev's contributions to the periodic table. How did the predictions he made using gaps in the table contribute to the understanding of undiscovered elements?

Answer: Mendeleev's periodic table was ground-breaking as he arranged elements by both atomic weights and properties. The table, despite having gaps, showcased elements with similar properties grouped together. Mendeleev's predictions using gaps demonstrated his foresight, allowing for the anticipation of undiscovered elements and their properties. This approach laid the foundation for the discovery of germanium, validating the accuracy of Mendeleev's periodic table.

Part 5 - Revision Tips: Focus on understanding Mendeleev's criteria for arranging elements and how the periodic table evolved with his predictions. Practice recalling key elements and their properties within the context of Mendeleev's contributions.

Part 6 - More Help: WANT 25% Off GCSE Science And Math Tuition OR Past Paper Revision Resources? Click this link - piacademy.co.uk and use this COUPON CODE - GCSE25.

Stay tuned for the next issue, where we'll delve into more intriguing topics in GCSE Science.