Problem 103 - Chemistry Central Science

Question

There are certain similarities in properties that exist between the first member of any periodic family and the element located below it and to the right in the periodic table. For example, in some ways Li resembles \(\mathrm{Mg}\), Be resembles \(\mathrm{Al}\), and so forth. This observation is called the diagonal relationship. Using what we have learned in this chapter, offer a possible explanation for this relationship.

Step-by-Step Solution

Answer

In conclusion, the diagonal relationship in the periodic table can be explained by considering factors such as electronic configuration, atomic size, and electronegativity. Elements with a diagonal relationship have similar electronic configurations (with a small difference in p-orbitals), comparable atomic sizes, and electronegativity values due to the periodic trends. These factors contribute to the similarities in properties between the elements in the diagonal relationship, such as Li with Mg and Be with Al.

Step 1: Identify elements and their positions

First, identify the elements that exhibit the diagonal relationship in the periodic table. These include: 1. Lithium (Li) and Magnesium (Mg) 2. Beryllium (Be) and Aluminum (Al) The relationship occurs between elements from Group 1 (alkali metals) and Group 2 (alkaline earth metals).

Step 2: Electronic configuration

Analyze the electronic configuration of these elements and how they are related. Electronic configurations are as follows: 1. Li: \(1s^2 2s^1\) 2. Mg: \(1s^2 2s^2 2p^6 3s^2\) 3. Be: \(1s^2 2s^2\) 4. Al: \(1s^2 2s^2 2p^6 3s^2 3p^1\) We can see that both Li and Mg have two outermost electrons in the s-orbital, and Be and Al have a similar configuration, with Al having one additional electron in the p-orbital.

Step 3: Atomic size

Examine the trend in atomic size across the periodic table. Typically, atomic size decreases going across a period (left to right) and increases going down a group (top to bottom). Due to this trend, elements having a diagonal relationship have similar atomic sizes. This similarity in atomic size can also partly explain the resemblance of properties between the elements with diagonal relationships.

Step 4: Electronegativity

Investigate the trend in electronegativity across the periodic table. Electronegativity generally increases going across a period (left to right) and decreases going down a group (top to bottom). Looking at the elements with diagonal relationships, we can see that they have similar electronegativity values: 1. Li: 0.98 2. Mg: 1.31 3. Be: 1.57 4. Al: 1.61 The similarity in electronegativity values also contributes to the likeness in properties between the elements with diagonal relationships.

Step 5: Conclusion

In conclusion, the diagonal relationship in the periodic table can be explained by considering factors such as electronic configuration, atomic size, and electronegativity. Elements with a diagonal relationship have similar electronic configurations (with a small difference in p-orbitals), comparable atomic sizes, and electronegativity values due to the periodic trends. These factors contribute to the similarities in properties between the elements in the diagonal relationship, such as Li with Mg and Be with Al.