Question

1. which arrangement of the following period 5 elements, from left to right, orders them with respect to their atomic size, from smallest to largest? a. rb; sr; in; sb; te b. in; rb; sb; sr; te c. te; sb; in; sr; rb d. in; sb; te; rb; sr 13. the diagram shows the electron configuration around the chlorine nucleus. chlorine has 17 protons. which of the following correctly completes the statement? chlorine has ____ valence electrons, and the effective nuclear charge, ( z_{\text {eff }} ), for the chlorine atom shown is ____. a. ( 7 ; 7+ ) b. ( 7 ; 7- ) c. ( 10 ; 7- ) d. ( 17 ; 7+ )

Explanation:

Question 12

• Atomic size decreases across a period from left to right.
• In Period 5, the order from left to right (increasing atomic number) is \(Rb\), \(Sr\), \(In\), \(Sb\), \(Te\). Since atomic size decreases across the period, the order from smallest to largest (opposite of left - to - right in the periodic table for atomic size) is \(Te\), \(Sb\), \(In\), \(Sr\), \(Rb\).

• Valence electrons are the electrons in the outermost shell. For chlorine (\(Cl\)), the electron configuration is \(2,8,7\), so there are \(7\) valence electrons.
• The formula for effective nuclear charge \(Z_{eff}=Z - S\), where \(Z\) is the atomic number (\(Z = 17\) for \(Cl\)) and \(S\) is the number of shielding electrons. For \(Cl\), \(S=10\) (the inner - shell electrons). So \(Z_{eff}=17- 10=7+\).

Answer:

C. Te; Sb; In; Sr; Rb

Question 13