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Sixty-two elements were known when Mendeleev published his periodic table of the elements in 1869 - Leaving Cert Chemistry - Question b - 2011
Question b
Sixty-two elements were known when Mendeleev published his periodic table of the elements in 1869. What was the basis (periodic law) used by Mendeleev in arranging ... show full transcript
Worked Solution & Example Answer:Sixty-two elements were known when Mendeleev published his periodic table of the elements in 1869 - Leaving Cert Chemistry - Question b - 2011
Step 1
What was the basis (periodic law) used by Mendeleev in arranging the elements in his periodic table?
Answer
Mendeleev's periodic law was based on the principle that the properties of elements are a periodic function of their atomic weights. When elements are arranged in order of increasing atomic weight, similar properties recur at regular intervals, allowing elements with similar chemical properties to be grouped together.
Step 2
Why did Mendeleev leave spaces in his periodic table, e.g. where the element germanium occurs in the modern periodic table?
Answer
Mendeleev left spaces in his periodic table for undiscovered elements. He predicted that as new elements were discovered, they would fit into these gaps, maintaining the continuity of increasing atomic weight and the grouping of elements with similar properties.
Step 3
Explain why he placed the element tellurium before the element iodine.
Answer
Mendeleev placed tellurium before iodine despite its higher atomic weight due to the properties of the elements. He prioritized the chemical properties over atomic weights when discrepancies occurred, as iodine exhibited properties more similar to group VII elements than tellurium.
Step 4
Step 5
The reactivity of the alkali metals increases down the group.
Answer
As you move down the group in the periodic table, the atomic size increases, leading to a weaker attraction between the nucleus and the outermost electron. This makes it easier for the electron to be removed, increasing reactivity.
Step 6
Step 7
Step 8
What do the electron configurations of the series of elements from scandium to zinc have in common?
Answer
The electron configurations of the series of elements from scandium to zinc indicate a gradual filling of the 3d subshell. Specifically, all these elements fill the 4s subshell before beginning to fill the 3d subshell, maintaining a consistent pattern in their electronic structure.