1.
In the modem periodic table, periods with heavier elements are longer than periods with lighter elements. This difference in period length exists because -
A the nuclei of lighter elements are more stable than those of heavier elements.
B. Othere are many more heavy elements than light elements.
CO Mendeleev originally designed the periodic table this way.
D.
D. heavier elements have more electron sub-shells than lighter elements

In the modern periodic table, periods with heavier elements are longer than periods with lighter elements. This difference in period length exists because there are many more heavy elements than light elements.

The periodic table is arrangement of elements in groups and periods. Elements in the same group of the periodic table have the same number of valence electrons while elements in the same period have the same number of shells.

Period 1 contains the lightest elements, hydrogen and helium. However, in the periodic table, we notice that periods with heavier elements are longer than periods with lighter elements. This is because there are many more heavy elements than light elements.

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