in this performance task you will answer four questions. the electron configurations of two unknown atoms…

in this performance task you will answer four questions. the electron configurations of two unknown atoms are shown electron configuration atom x atom y based on the electron configuration of atom y, to which group in the periodic table does it belong? 1 8 7 2
Answer
Explanation:
Step1: Count valence electrons
The group number of an element in the periodic - table (for main - group elements) is related to the number of valence electrons. Valence electrons are the electrons in the outermost shell. By counting the electrons in the outermost shell of Atom Y, we can determine its group.
Step2: Identify the group
Atom Y has 7 electrons in its outermost shell. For main - group elements, elements with 7 valence electrons belong to Group 17 (or Group 7 in the old - style numbering without the transition metals separated). Among the given options, the closest representation is 7.
Answer:
C. 7