Answer the following questions about the characteristics of the elements in Group 2 (the alkaline earths).
How do they react with iodine?
How do they react with water?
How do they react with oxygen?
Which reacts the most vigorously?
Which element in the group is the most metallic in character?
To answer questions about the characteristics of the elements in Group 2 (the alkaline earths), we will look at their reactivity with iodine, water, and oxygen, as well as their metallic character.
1. How do they react with iodine?
To determine how Group 2 elements react with iodine, you can refer to their position on the periodic table. Group 2 elements have two valence electrons, and they are known to lose these electrons to form a +2 cation. Iodine, on the other hand, has seven valence electrons and tends to gain one electron to form a -1 anion. Therefore, Group 2 elements react with iodine by losing their two valence electrons to form a 2+ cation, while iodine accepts two electrons to form an iodide ion (I-).
2. How do they react with water?
Group 2 elements react with water, but their reactivity increases as you move down the group. The reaction with water produces metal hydroxides and hydrogen gas. For example, calcium (Ca), the first element in Group 2, reacts slowly with water to form calcium hydroxide (Ca(OH)2) and hydrogen gas (H2). As you go down the group, the reactivity increases, and the reaction becomes more vigorous. Strontium (Sr) and barium (Ba), the elements below calcium, react more vigorously with water, producing their respective hydroxides and hydrogen gas.
3. How do they react with oxygen?
Group 2 elements readily react with oxygen to form metal oxides. The reactivity increases as you move down the group. For example, calcium reacts with oxygen in the air to form calcium oxide (CaO), commonly known as quicklime. Similar to the reactivity with water, strontium and barium react more vigorously with oxygen, forming their respective oxides.
4. Which reacts the most vigorously?
As mentioned earlier, the reactivity of Group 2 elements increases as you move down the group. Therefore, barium, the last element in Group 2, reacts the most vigorously with iodine, water, and oxygen compared to the other elements in the group.
5. Which element in the group is the most metallic in character?
The metallic character increases as you move down a group in the periodic table. Therefore, the element at the top of Group 2, beryllium (Be), is considered the least metallic in character. As you go down the group, the metallic character increases, with barium (Ba) being the most metallic element in Group 2.
In conclusion, Group 2 elements react with iodine by losing their valence electrons, react with water to form metal hydroxides and hydrogen gas, and react with oxygen to form metal oxides. Barium is the most reactive element in the group, while barium is also the most metallic in character.