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.
... show full transcript
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?
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Mendeleev reversed the order of tellurium and iodine because iodine, with an atomic weight of 127, has similar properties to elements in Group 7, while tellurium, with an atomic weight of 128, has properties that better align with those of elements in Group 6.
Step 2
Why did Mendeleev's periodic table become more widely accepted than previous versions?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Mendeleev's periodic table became more widely accepted because he had predicted the properties of missing elements, which later matched the elements that were discovered. This predictive power, alongside the arrangement of elements according to properties and atomic weights, made it more reliable than earlier tables.
Step 3
What is the modern name for atomic weight?
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The modern name for atomic weight is relative atomic mass.
Step 4
Complete the sentence.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
In the modern periodic table, the elements are arranged in order of increasing atomic number.
Step 5
Predict the formula of an astatine molecule.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The formula of an astatine molecule is At₂.
Step 6
Predict the state of astatine at room temperature.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The state of astatine at room temperature is solid.
Step 7
Describe what you would see when sodium reacts with chlorine.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
When sodium reacts with chlorine, you would observe a bright yellow flame, and solid sodium would disappear as it forms sodium chloride. The chlorine gas would turn to a white smoke as it combines with sodium.
