Express in factorial notation 15x14x13x12 please urgent​

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.

So the main goal for the elements is stability which is a complete/full valence shell and typically the magic number for a stable element is 8 valence electron but not always. so elements to the left of the periodic table tend to be way less stable then those on the right, so the elements on the left are much more reactive.

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