Question

1. which list arranges the elements na, li, k, rb, and cs in order of increasing ionization energy (from left to right)?

a. cs; rb; k; na; li
b. cs; li; na; k; rb
c. na; li; k; rb; cs
d. li; na; k; rb; cs

1. with the exception of he, how many valence electrons do noble gases have?

a. 3
b. 4
c. 6
d. 8

1. which characteristic is not a periodic trend?

a. atomic radius
b. electron affinity
c. ionization energies
d. number of elements in a group

Explanation:

• Question 14: Ionization energy decreases down a group. These elements (Na, Li, K, Rb, Cs) are in Group 1. As we go down the group (Cs is the lowest, then Rb, K, Na, Li), ionization energy increases.
• Question 15: Noble gases (except He) have a full valence shell. The valence shell configuration for most noble gases (Ne, Ar, Kr, etc.) is \(ns^{2}np^{6}\), giving 8 valence electrons.
• Question 16: Atomic radius, electron - affinity, and ionization energy show periodic trends (vary with the position in the periodic table). The number of elements in a group is a fixed property (e.g., Group 1 has a certain number of elements that doesn't change as a 'trend' across the table).

Answer:

1. A. Cs; Rb; K; Na; Li
2. D. 8
3. D. number of elements in a group