Problem 21 - Chemistry: The Central Science

Question

Give a reason why hydrogen might be placed along with the group 1 A elements of the periodic table.

Step-by-Step Solution

Answer

Hydrogen shares similarities with Group 1A elements, including having one electron in its outermost shell, high reactivity, and the ability to form compounds with a +1 oxidation state. These properties provide a reason to place hydrogen alongside Group 1A elements in the periodic table, despite some differences such as being a nonmetal and having a lower atomic mass.

Step 1: Understand the properties of hydrogen

Before explaining why hydrogen might be placed alongside Group 1A elements, it is essential to comprehend hydrogen's properties. Hydrogen is the lightest and simplest element in the periodic table, with atomic number 1 and atomic mass 1.00794. Hydrogen forms a diatomic gas (H2) at room temperature and is highly reactive. It exists in various isotopes, the most common being protium (¹H), deuterium (²H), and tritium (³H).

Step 2: Understand the properties of Group 1A elements

Group 1A elements, also known as alkali metals, include elements such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These elements have the following properties: - They are very reactive and readily form compounds with other elements. - They have one electron in their outermost shell, making them highly electropositive (easily lose an electron to become positively charged). - They typically form +1 ions when combined with nonmetals. - They are soft, shiny metals with low melting points.

Step 3: Comparing hydrogen with Group 1A elements

Hydrogen has similarities with Group 1A elements, which make it reasonable to place it alongside those elements: - Both hydrogen and Group 1A elements have one electron in their outermost shell. This property enables hydrogen to lose one electron, similar to alkali metals, resulting in a +1 oxidation state in their compounds. - Hydrogen, like Group 1A elements, is highly reactive. This reactivity comes from its ability to lose its one valence electron easily. - Hydrogen can form compounds with nonmetals through ionic or covalent bonding, much like alkali metals.

Step 4: Conclusion

Hydrogen exhibits properties that are similar to those of Group 1A elements, specifically its single electron in the outermost shell, high reactivity, and ability to form compounds that display the oxidation state of +1. This is the reason why hydrogen might be placed alongside Group 1A elements in the periodic table. However, it is important to note that hydrogen also has some distinctly different properties from alkali metals, such as being a nonmetal, existing as a diatomic gas, and having a much lower atomic mass.