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In 1869, Dmitri Mendeleev produced his periodic table of the elements - AQA - GCSE Chemistry - Question 3 - 2014 - Paper 3
Question 3
In 1869, Dmitri Mendeleev produced his periodic table of the elements. Mendeleev placed the alkali metals in the same group. 3 (a) What evidence did Mendeleev use ... show full transcript
Worked Solution & Example Answer:In 1869, Dmitri Mendeleev produced his periodic table of the elements - AQA - GCSE Chemistry - Question 3 - 2014 - Paper 3
Step 1
What evidence did Mendeleev use to decide that the alkali metals should be in the same group?
Answer
Mendeleev placed alkali metals in the same group based on their similar chemical properties. He observed that they shared characteristics such as high reactivity and the formation of similar compounds with halogens, suggesting a commonality that justified their grouping.
Step 2
Step 3
Describe how the elements in the modern periodic table are arranged: in terms of electrons.
Answer
Elements in the same group of the periodic table have the same number of electrons in their outer shell. This means that as you move down the group, the number of electrons increases, with elements having uniform arrangements in their outermost energy level.
Step 4
State two properties of transition elements that make them more useful than alkali metals for making water pipes.
Answer
- Transition elements are generally stronger and harder than alkali metals, making them more suitable for structural applications such as pipes.
- Transition elements have higher melting points, allowing them to withstand higher temperatures without deformation.
Step 5
Describe and explain the trend in reactivity of the alkali metals (Group 1).
Answer
The reactivity of alkali metals increases as you move down the group. This is due to the outer electron being further from the nucleus, which results in a weaker attraction between the outer electron and the nucleus. Consequently, the outer electron is lost more easily, leading to higher reactivity.