Question

question 26 (1 point)listenrank the following atoms in order of decreasing effective nuclear charge ($z_{eff}$) (i.e., highest to lowest):fluorine (f)rubidium (rb)nitrogen (n)beryllium (be)question 27 (1 point)listenrank the following atoms in order of increasing effective nuclear charge ($z_{eff}$) (i.e., lowest to highest):silicon (si)calcium (ca)sulfur (s)rubidium (rb)

Explanation:

Step1: Recall $Z_{eff}$ trends

For main-group atoms:

1. Across a period (left to right), $Z_{eff}$ increases (protons added, shielding from inner electrons changes little).
2. Down a group (top to bottom), $Z_{eff}$ for valence electrons changes very little (protons added, but new full electron shells add significant shielding).

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For Question 26 (Decreasing $Z_{eff}$):

Step2: List atomic numbers/periods

• F (Z=9, Period 2, Group 17)
• N (Z=7, Period 2, Group 15)
• Be (Z=4, Period 2, Group 2)
• Rb (Z=37, Period 5, Group 1)

Step3: Rank by period/group

Period 2 atoms have higher $Z_{eff}$ than Period 5 (Rb). Within Period 2, $Z_{eff}$ increases rightward.
Rank: F > N > Be > Rb

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For Question 27 (Increasing $Z_{eff}$):

Step4: List atomic numbers/periods

• Rb (Z=37, Period 5, Group 1)
• Ca (Z=20, Period 4, Group 2)
• Si (Z=14, Period 3, Group 14)
• S (Z=16, Period 3, Group 16)

Step5: Rank by period/group

Lower period atoms have lower $Z_{eff}$ than higher periods. Within Period 3, $Z_{eff}$ increases rightward.
Rank: Rb < Ca < Si < S

Answer:

Question 26 (highest to lowest):

1. Fluorine (F)
2. nitrogen (N)
3. Beryllium (Be)
4. Rubidium (Rb)

Question 27 (lowest to highest):

1. Rubidium (Rb)
2. Calcium (Ca)
3. Silicon (Si)
4. sulfur (S)