Problem 7 - A Complete Resource Book in Chemistry for JEE Main

Question

Which one of the following is a metalloid? (a) phosphorus (b) antimony (c) nitrogen (d) bismuth

Step-by-Step Solution

Answer

Antimony (b) is a metalloid.

Step 1: Understand the Element Categories

First, let's define what a metalloid is. Metalloids are elements that have properties intermediate between metals and nonmetals. They are typically semiconductive and often have a mix of metallic and nonmetallic properties. Commonly recognized metalloids include elements like boron, silicon, and arsenic.

Step 2: Identify the Elements Listed

We need to identify which of the provided options are metalloids. Let's review each: - Phosphorus: A nonmetal. - Antimony: Known to be a metalloid. - Nitrogen: A nonmetal. - Bismuth: A metal.

Step 3: Verify the Metalloid

Check the periodic table to ensure that antimony is indeed classified as a metalloid. Antimony ( extbf{Sb}) has atomic number 51, and it is typically placed in the same group as arsenic, another metalloid. This confirms its metalloid status.

Key Concepts

Element Classification

Elements are fundamental substances that consist only of one kind of atom. They can be classified into three main categories: metals, nonmetals, and metalloids. This classification is based on their physical and chemical properties.

• Metals: These are typically solid at room temperature (except mercury), good conductors of heat and electricity, and have high melting and boiling points. They can be formed into shapes, such as sheets or wires, due to their malleability and ductility.
• Nonmetals: These elements are found on the right side of the periodic table. They are typically gases or brittle solids at room temperature and do not conduct electricity well. For example, oxygen and nitrogen.
• Metalloids: These elements possess mixed properties of both metals and nonmetals, making them unique. They are often semiconductors, meaning they can conduct electricity under certain conditions. Antimony is a good metalloid example.

Understanding these categories helps in predicting the properties and reactions of elements. Look for common physical traits and electronic configurations when determining the classification of an element.

Chemical Properties

The chemical properties of elements determine how they react with other substances. Each group in the periodic table shares similar chemical properties due to their similar electronic configurations. For instance, metalloids, which are elements like silicon and antimony, have variable chemical reactivity.
They can form alloys with metals, participate in chemical reactions as semiconductors, and sometimes exhibit oxidation states that are not fixed.

• Reactivity: Metalloids may behave as either metals or nonmetals in chemical reactions. Their ability to "switch sides" in terms of chemical reactivity is quite unique.
• Formation of Compounds: Metalloids can form compounds with both metals and nonmetals. For instance, antimony trioxide is commonly used as a flame retardant and is obtained by the oxidation of antimony.

Thus, when predicting reactions of metalloids or any element, considering its place in the periodic table and known chemical behavior offers valuable insight.

Periodic Table

The periodic table is an organized chart of elements arranged by increasing atomic number. It reflects recurring chemical properties. This organization allows for easy prediction of element properties and behaviors based on their positions.

• Groups: Vertical columns called groups contain elements with similar chemical properties. Metalloids are found along the diagonal line that separates metals from nonmetals and often intermingle with groups in this area.
• Periods: Horizontal rows known as periods indicate elements with the same number of atomic orbitals. Moving across a period from left to right shows a change from metallic to non-metallic character.

The periodic table is a vital tool in chemistry, acting as a map for understanding the relationship between different elements. Knowing where metalloids and other elements fit within this table helps in grasping their expected interactions and utility in chemical processes.