Question

1. use a periodic table to choose the best answer. which element is more chemically reactive? br se 13) use a periodic table to choose the best answer. which element is more chemically reactive? cs rb 14) use a periodic table to choose the best answer. which element is more chemically reactive? f cl

Explanation:

• For question 12: Bromine (\(Br\)) is a halogen. Selenium (\(Se\)) is a chalcogen. Halogens are more reactive than chalcogens in the same period as halogens need only one electron to complete their octet.
• For question 13: Cesium (\(Cs\)) and Rubidium (\(Rb\)) are alkali metals. As we move down the group of alkali metals, the atomic size increases, and the outermost electron is more easily lost. Cesium is below rubidium in the group, so it is more reactive.
• For question 14: Fluorine (\(F\)) and Chlorine (\(Cl\)) are halogens. As we move down the group of halogens, the atomic size increases, and the attraction for the incoming electron decreases. Fluorine is above chlorine in the group, so it is more reactive.

Answer:

1. Br
2. Cs
3. F