Problem 6 - A Complete Resource Book in Chemistry for JEE Main

Question

The elements with atomic numbers \(9,17,35,53\) and 85 (a) noble gases (b) light metals (c) halogens (d) heavy metals

Step-by-Step Solution

Answer

The elements with atomic numbers 9, 17, 35, 53, and 85 are halogens.

Step 1: Identify the elements by their atomic numbers

The atomic numbers given are 9, 17, 35, 53, and 85. First, identify the corresponding elements from the periodic table. They are Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At) respectively.

Step 2: Categorize the elements

Examine the group of elements identified in Step 1. These elements, F, Cl, Br, I, and At, belong to Group 17 of the periodic table, which is known as the halogens.

Step 3: Match the group with the categories given

Compare the group identified in Step 2 (halogens) with the given options: (a) noble gases, (b) light metals, (c) halogens, (d) heavy metals. The elements belong to the halogens category.

Key Concepts

Periodic Table

The periodic table is a structured arrangement of chemical elements, organized by increasing atomic number. Atomic numbers define how many protons are in an atom's nucleus. The table helps us understand and predict chemical properties of elements.

• Vertical columns on the periodic table are called groups or families.
• Horizontal rows are called periods.
• Each element is represented by a unique symbol and an atomic number.

The periodic table is a powerful tool in chemistry, serving as a roadmap for students and scientists to understand element properties and relationships.

Group 17 Elements

Group 17 of the periodic table consists of the halogens, which are placed in the second-last column from the right. These elements are known for their high reactivity, especially Fluorine and Chlorine. Halogens are :

• Non-metals
• Highly electronegative
• Common in nature, but usually found in compounds rather than in their pure form

The halogens include Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At). These elements form salts when combined with metals, and are known for their distinctive colors and odors in the gas phase.

Atomic Numbers

Atomic numbers are crucial in defining the identity of an element. Each element on the periodic table is assigned a number that tells us the number of protons in its nucleus. For instance, the atomic number of Fluorine is 9, which means it has 9 protons.

• Elements are arranged in increasing order of atomic numbers in the periodic table.
• Atomic number is a fundamental property that differentiates one element from another.
• It influences the element's chemical properties and its reactivity.

Atomic numbers help us understand the structure of atoms and predict how different elements will interact in chemical reactions.