The chemical characteristics or reactivity of a chemical element is highly (mostly) dependent on the: number of valence electrons in its outermost shell.
A chemical characteristic can be defined as the properties of a chemical element or compound that is mainly observable and measurable during a chemical reaction such as reactivity.
A valence electron can be defined as the number of electrons that are present in the outermost shell of an atom of a chemical element.
In Chemistry, the number of valence electrons (valency) is a property that is typically used to determine the chemical characteristics or reactivity of all chemical elements.
In conclusion, the chemical characteristics or reactivity of a chemical element is highly (mostly) dependent on the number of valence electrons in its outermost shell.
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