This question is about elements in the periodic table - AQA - GCSE Chemistry Combined Science - Question 4 - 2019 - Paper 1
Question 4
This question is about elements in the periodic table.
1. What order did scientists use to arrange elements in early periodic tables?
2. In the early periodic tabl... show full transcript
Worked Solution & Example Answer:This question is about elements in the periodic table - AQA - GCSE Chemistry Combined Science - Question 4 - 2019 - Paper 1
Step 1
What order did scientists use to arrange elements in early periodic tables?
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Answer
Early scientists arranged elements based on atomic weight. They observed periodic trends where elements with similar properties displayed repeating characteristics at regular intervals.
Step 2
Give one way Mendeleev did this.
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Answer
Mendeleev placed gaps or spaces in his periodic table to accommodate undiscovered elements and adjusted the order of elements based on their properties rather than strictly adhering to atomic weight.
Step 3
Explain why the boiling points in Table 2 are low.
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Answer
The low boiling points of elements in Table 2 are due to the weak intermolecular forces present. These weak forces require less energy to overcome, resulting in lower boiling points.
Step 4
Explain the trend in the boiling points in Table 2.
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Answer
The trend in boiling points shows an increase down the group. As we go from fluorine to bromine, the size of the molecules increases, leading to stronger intermolecular forces that require more energy to overcome, hence higher boiling points.
Step 5
Explain why neon is unreactive.
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Neon is unreactive because it has a stable electron configuration with a complete outer shell. This stability means it does not readily form bonds with other elements.
Step 6
Give the electronic structure of neon in your answer.
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Answer
The electronic structure of neon is 1s² 2s² 2p⁶, indicating that its outer shell is filled, contributing to its lack of reactivity.
Step 7
How many atoms are there in 1 g of argon?
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Answer
To find the number of atoms in 1 g of argon, we use the formula:
Number of atoms =
rac{mass ext{ (g)}}{molar mass ext{ (g/mol)}} imes ext{Avogadro's constant}
Number of atoms in 1 g of argon =
rac{1 ext{ g}}{40 ext{ g/mol}} imes 6.02 imes 10^{23} ext{ atoms/mol} = 1.51 imes 10^{22} ext{ atoms}.
