Question

for the following groups of elements, arrange elements in increasing order of electron affinity. part 1 of 3 k, rb, cs part 2 of 3 cl, i, br part 3 of 3 ba, p, na, si

Explanation:

Step1: Recall electron - affinity trend

Electron affinity generally increases across a period and decreases down a group. Metals have low electron - affinities and non - metals have high electron - affinities.

Step2: Analyze Part 1 (K, Rb, Cs)

K, Rb, Cs are alkali metals in Group 1. As we go down the group, the atomic size increases, and the added electron is farther from the nucleus, so electron affinity decreases. So the order is Cs < Rb < K.

Step3: Analyze Part 2 (Cl, I, Br)

Cl, Br, I are halogens in Group 17. As we go down the group, the atomic size increases, and the electron affinity decreases. So the order is I < Br < Cl.

Step4: Analyze Part 3 (Ba, P, Na, Si)

Ba is an alkaline - earth metal, Na is an alkali metal, P is a non - metal, and Si is a metalloid. Ba and Na are metals with low electron affinities. Among them, Ba has a lower electron affinity than Na due to its larger size. Si has a higher electron affinity than metals, and P has a relatively high electron affinity among these elements. So the order is Ba < Na < Si < P.

Answer:

Part 1: Cs < Rb < K
Part 2: I < Br < Cl
Part 3: Ba < Na < Si < P