Question

1. from the table below, determine the atomic number of the noble gas at the end of period 5.

a. 18
b. 36
c. 54
d. 52
54
52
18
36

Explanation:

Step1: Recall the number of elements in each period

Period 1 has 2 elements, period 2 has 8 elements, period 3 has 8 elements, period 4 has 18 elements, and period 5 has 18 elements.

Step2: Calculate the cumulative number of elements up to period 5

Add the number of elements in each period: \(2 + 8+8 + 18+18\).
First, \(2+8 = 10\), then \(10 + 8=18\), then \(18+18 = 36\), and finally \(36+18=54\).

Answer:

C. 54