The Development of the Periodic Table

Newlands' Law of Octaves

• Arranged according to the ascending order of the elements' atomic mass.
• Every eight element, starting from a given one, had similar properties as the first one.

However, his classification was not accepted by the scientific community because:

• Newlands' rule did not hold true at all for elements beyond calcium.
• He did not leave blank spaces in his table for undiscovered elements.

Mendeleev's Periodic Table

• Arranged the elements in order of increasing R.A.M.
• He left gaps where necessary to ensure that similar elements were grouped together.
• Vertical columns = groups
• Horizontal columns = periods

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