Question

(a) Without refering to Figure 4.8 , give the oxidation numbers of the alkali and alkaline earth metals in their compounds. (b) Give the highest oxidation numbers that the Groups \(3 \mathrm{~A}-7 \mathrm{~A}\) elements can have.

Short answer

(a) Alkali metals: +1, Alkaline earth metals: +2. (b) Group 3A: +3, 4A: +4, 5A: +5, 6A: +6, 7A: +7.

Step-by-step solution

Oxidation Numbers for Alkali Metals

Alkali metals are found in Group 1 of the periodic table and include elements like lithium (Li), sodium (Na), and potassium (K). These elements typically lose one electron to achieve a stable electron configuration, resulting in an oxidation number of +1 in their compounds.

Oxidation Numbers for Alkaline Earth Metals

Alkaline earth metals are found in Group 2 of the periodic table and include elements like beryllium (Be), magnesium (Mg), and calcium (Ca). These elements typically lose two electrons when forming compounds, leading to an oxidation number of +2.

Highest Oxidation Numbers for Group 3A Elements

Group 3A elements include boron (B), aluminum (Al), and gallium (Ga). These elements can achieve an oxidation state of +3, as they can form compounds where they lose three electrons.

Highest Oxidation Numbers for Group 4A Elements

Group 4A elements like carbon (C) and silicon (Si) can have an oxidation number of up to +4, corresponding to the loss of four valence electrons or forming covalent compounds with four more electronegative elements.

Highest Oxidation Numbers for Group 5A Elements

Group 5A elements, such as nitrogen (N) and phosphorus (P), can have high oxidation numbers like +5 by losing all five valence electrons or participating in covalent bonding with more electronegative atoms.

Highest Oxidation Numbers for Group 6A Elements

Elements in Group 6A, such as oxygen (O) and sulfur (S), can have a maximum oxidation number of +6 after losing or sharing all six valence electrons with more electronegative atoms.

Highest Oxidation Numbers for Group 7A Elements

Group 7A contains the halogens, like fluorine (F) and chlorine (Cl). The highest oxidation number these elements can exhibit is +7, typically when forming compounds with very electronegative atoms or in polyatomic ions.

Key concepts

Alkali Metals

Alkali metals are a fascinating group of elements that can be found in Group 1 of the periodic table. They include familiar elements like lithium (Li), sodium (Na), and potassium (K). What makes alkali metals interesting is their tendency to lose one electron easily.
This characteristic behavior is due to their single electron in their outermost shell, which they readily give up to achieve a stable electronic arrangement, often similar to the noble gas configuration.
This results in a consistent oxidation number of +1 for alkali metals in their chemical compounds.

• Located in Group 1 of the periodic table
• Consistently show an oxidation number of +1
• Elements: Lithium, Sodium, Potassium

They're highly reactive, particularly with water, forming hydroxides and releasing hydrogen gas. This reactivity is one of the reasons why they are so important in chemistry, both in terms of practical applications and theoretical understanding of chemical behaviors.

Alkaline Earth Metals

The alkaline earth metals are found in Group 2 of the periodic table and include elements like beryllium (Be), magnesium (Mg), and calcium (Ca). These elements share a common trait: they have two electrons in their outermost shell. Naturally, to reach a stable electron configuration, they lose both electrons, resulting in a typical oxidation number of +2.

• Located in Group 2 of the periodic table
• Show an oxidation number of +2 in compounds
• Elements: Beryllium, Magnesium, Calcium

Alkaline earth metals are less reactive than alkali metals but still, they react with water and acids, often forming hydroxides. They are employed in numerous applications ranging from construction materials (such as in cement and plaster) to important roles in biological systems.

Periodic Table Groups

The periodic table is a detailed chart that organizes elements based on their atomic number, electron configurations, and recurring chemical properties. It is divided into groups and periods. The groups are the vertical columns, and they contain elements that have similar properties.

• Alkali metals belong to Group 1
• Alkaline earth metals belong to Group 2
• Other notable groups include halogens (Group 7A) and noble gases (Group 8A)

Each group is designed to showcase elements with similar outer electron configurations, which is why elements in the same group exhibit similar chemical behaviors.
This structure is particularly useful in predicting how different elements will react with one another and is a cornerstone in the study and application of chemistry.
It's fascinating to see that although the members of a group share certain properties, each element also has unique characteristics that make them interesting individually. This balance of shared and unique traits forms the bedrock of understanding chemical interactions and properties.