Question

part d: application

1. arrange the following elements in order of increasing atomic radius: k, na, rb, cs.
2. arrange the following elements in order of decreasing atomic radius: o, s, se, te.
3. circle the atom in each pair with the larger radius:

a) mg or ca
b) c or si
c) cl or br
d) li or f

Explanation:

Step1: Recall atomic - radius trend

Atomic radius increases down a group in the periodic table due to the addition of electron - shells.

Step2: Solve question 16

K, Na, Rb, Cs are in Group 1. As we go down the group (Na < K < Rb < Cs), the atomic radius increases. So the order is Na, K, Rb, Cs.

Step3: Solve question 17

O, S, Se, Te are in Group 16. As we go down the group, the atomic radius increases. So in decreasing order, it is Te, Se, S, O.

Step4: Solve question 18a

Mg and Ca are in Group 2. Ca is below Mg, so Ca has a larger radius.

Step5: Solve question 18b

C and Si are in Group 14. Si is below C, so Si has a larger radius.

Step6: Solve question 18c

Cl and Br are in Group 17. Br is below Cl, so Br has a larger radius.

Step7: Solve question 18d

Li and F are in Period 2. As we move from left to right across a period, the atomic radius decreases. Li is to the left of F, so Li has a larger radius.

Answer:

1. Na, K, Rb, Cs
2. Te, Se, S, O

18a. Ca
18b. Si
18c. Br
18d. Li