Answer:
The number of atoms in the outermost shell
Explanation:
For example, the electron shells in the alkali metals contain the following numbers of electrons:
Li: 2, 1
Na: 2, 8, 1
K: 2, 8, 8, 1
They all have one electron in their outermost shell, and they have similar chemical properties.
The number 6.022 × 1023 indicating the number of atoms or molecules in a mole of any substance
Answer:
was difficult to place isotopes of elements as they have the same chemical properties but different atomic masses. It was not possible to predict how many elements could be discovered between two heavy elements as the rise in atomic mass is not uniform.
Answer:
12 grams
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