This question is about the periodic table - AQA - GCSE Chemistry - Question 1 - 2019 - Paper 1
Question 1
This question is about the periodic table.
In the 19th century, some scientists tried to classify the elements by arranging them in order of their atomic weights.
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Worked Solution & Example Answer:This question is about the periodic table - AQA - GCSE Chemistry - Question 1 - 2019 - Paper 1
Step 1
Why did Mendeleev reverse the order of these two elements?
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Answer
Mendeleev reversed the order of tellurium and iodine because he recognized that iodine's properties were more similar to those of elements in Group 7, such as bromine and chlorine. This alignment based on chemical properties took precedence over atomic weight.
Step 2
Why did Mendeleev's periodic table become more widely accepted than previous versions?
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Mendeleev's periodic table became more widely accepted because he predicted the properties of missing elements, and subsequent discoveries of these elements matched his predictions. This pattern established credibility for his arrangement of the periodic table.
Step 3
What is the modern name for atomic weight?
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The modern name for atomic weight is 'relative atomic mass.'
Step 4
Complete the sentence.
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In the modern periodic table, the elements are arranged in order of increasing atomic number.
Step 5
Predict: the formula of an astatine molecule and the state of astatine at room temperature.
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The formula of an astatine molecule is At₂ and the state of astatine at room temperature is solid.
Step 6
Describe what you would see when sodium reacts with chlorine.
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When sodium reacts with chlorine, you would observe a vigorous reaction where sodium burns with a bright yellow flame, producing white sodium chloride (table salt), which may appear as a white solid or smoke.
