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The reactivity of metals increases as you move left in a period and as you move down in a group, so Marie needs to know the period and group of the element inside each box. Boxes that show locations in groups 1 or 2 or in period 8 contain the most reactive elements.

Explanation:

The Group Number of the elements.

Explanation:

If Marie knew the group number of the elements, then she could determine the amount of valence electrons each element has and their reactivity rate. For example, if one box tells her that an element is located in group 18, then she could determine that the element is not very reactive. This is because elements in group 18 have 8 valence electrons, which makes them stable/unreactive.

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explanation:

physics means: "the branch of science concerned with the nature and properties of matter and energy. the subject matter of physics, distinguished from that of chemistry and biology, includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."