It appears that you are referencing terminology related to the periodic table of elements. Here's a clarification of the terms you've mentioned:
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AxA or A family: In the context of the periodic table, elements are often categorized into groups or families based on their similar properties. The "A" designation typically refers to the main group elements (especially in older notations), which include the s- and p-block elements. For example, Group 1 (alkali metals) and Group 2 (alkaline earth metals) are considered "A" families.
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Vertical column/Group: The vertical columns in the periodic table are called groups. Elements in the same group generally exhibit similar chemical properties because they have the same number of valence electrons.
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C subset: The "C" designation often refers to the transition metals, which are located in the d-block of the periodic table. These are sometimes referred to as "B" groups in older classifications.
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Period: The horizontal rows in the periodic table are called periods. Each period corresponds to the number of electron shells that the elements in that row possess.
If you have a specific question or need more detailed information about any of these terms or concepts, feel free to ask!