EasyChemistryHigh School (9–10)GeneralThe Periodic Table › Development of the Periodic TableConceptualBoard Exam
Give two reasons why Newlands' law of octaves was not accepted for all of the elements…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Give two reasons why Newlands' law of octaves was not accepted for all of the elements. Then say what part of his idea was right.
Need a reminder? The key ideaShow
Dobereiner: in a triad of three similar elements, the middle atomic mass is close to the average of the other two. Newlands: in order of atomic mass, every eighth element is like the first, which worked only up to calcium.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. First reason. The pattern held only up to calcium. Heavier elements did not fit their columns.
Step 2. Second reason. To force a fit, he put two elements in one box and grouped unlike elements, such as iron with oxygen and sulphur.
Step 3. What was right. Properties do repeat at regular steps. That idea is the base of the periodic table.
Answer: it failed after calcium, and it forced unlike elements together; but the idea of repeating properties was right.
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