Ch.22 - The Main Group Elements

McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook

McMurry 8th Edition

Ch.22 - The Main Group Elements

Problem 22.84

Chapter 22, Problem 22.84

List three ways in which the properties of boron differ from those of the other group 3A elements.

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1. Boron is a metalloid, while the other elements in Group 3A (Aluminium, Gallium, Indium, Thallium) are metals. This means that boron has properties of both metals and nonmetals, while the other elements in this group are primarily metallic in nature.

2. Boron has a much higher melting point and boiling point compared to the other elements in Group 3A. This is due to the strong covalent bonding in boron, while the other elements in this group have metallic bonding which is generally weaker.

3. Boron is less reactive than the other elements in Group 3A. This is because boron has a stable half-filled p orbital, making it less likely to participate in chemical reactions. The other elements in Group 3A are more reactive due to their tendency to lose electrons and form positive ions.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Group 3A Elements

Group 3A elements, also known as Group 13 in the periodic table, include boron, aluminum, gallium, indium, and thallium. These elements share similar valence electron configurations, typically having three electrons in their outer shell. However, their properties can vary significantly due to differences in atomic size, electronegativity, and metallic character as you move down the group.

Metalloid vs. Metal

Boron is classified as a metalloid, which means it exhibits properties of both metals and nonmetals, such as being a poor conductor of electricity and having a high melting point. In contrast, the other Group 3A elements are metals, characterized by good electrical conductivity, malleability, and ductility. This distinction leads to significant differences in their chemical reactivity and physical properties.

Oxidation States

Boron primarily exhibits a +3 oxidation state in its compounds, but it can also show a +1 state in certain cases. The other Group 3A elements predominantly exhibit +3 oxidation states as well, but they can also form +1 oxidation states more readily due to their metallic nature. This difference in oxidation states influences the types of compounds formed and their chemical behavior.

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Oxidation Numbers

Related Practice

Textbook Question

Using the shorthand notation of Figure 22.9, draw the structure of the silicate anion in:

(a) K₄SiO₄ (b) Ag₁₀Si₄O₁₃

What is the relationship between the charge on the anion and the number of terminal O atoms?

Textbook Question

a. Why is the SO₃ molecule trigonal planar but the SO₃^2– ion is trigonal pyramidal?

Textbook Question

Why are CO and CN^– so toxic to humans?

Textbook Question

An important physiological reaction of nitric oxide (NO) is its interaction with the superoxide ion (O₂^–) to form the peroxynitrite ion (ONOO^–).

a. Write electron-dot structures for NO, O₂^–, and ONOO^–, and predict the O–N–O bond angle in ONOO^–.

Textbook Question

What is the hybridization and geometry around carbon atoms in graphene? Explain why graphene is an excellent conductor of electricity.

Textbook Question

The following pictures represent structures of the hydrides of four second-row elements:

(1)

(2)

(3)

(4)

(a) Which compound has the highest melting point?