Question

a group in the periodic table has the same
a) shell number.
b) number of neutrons.
c) number of outer shell electrons.
d) number of protons.
question 18 (5 points)
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elements in the same period
a) have the same number of valence electrons.
b) have the same number of protons.
c) have the same principal quantum number.

Explanation:

• For the first question:
• In the periodic table, a group (vertical column) has elements with the same number of outer - shell (valence) electrons. For example, group 1 elements (alkali metals) all have 1 valence electron.
• Shell number (A) is related to periods (horizontal rows). The number of neutrons (B) varies among different isotopes of elements and is not a characteristic of a group. The number of protons (D) is unique for each element (atomic number) and not the same within a group.
• For the second question:
• Elements in the same period (horizontal row) have the same principal quantum number (\(n\)). The principal quantum number represents the energy level or shell of the outermost electrons.
• Elements in the same period do not have the same number of valence electrons (A) (valence electrons increase from left to right in a period). The number of protons (B) (atomic number) increases from left to right in a period.

Answer:

• First question: C. number of outer shell electrons.
• Second question: C. have the same principal quantum number.