Question

The statement that is not correct for the periodic classification of elements is (1) The properties of elements are the periodic functions of their outer electronic configurations. (2) Non-metallic elements arc lesser in number than metallic elements. (3) For transition elements the d-subshells are filled with electrons monotonically with increase in atomic number. (4) In the periodic table metallic elements appear in the right-hand columns.

Short answer

Statement 4: 'In the periodic table metallic elements appear in the right-hand columns.' This is incorrect.

Step-by-step solution

Understand the Given Statements

Read each statement carefully to understand what it claims about the periodic table and the classification of elements.

Analyze Statement 1

Statement 1 says that 'The properties of elements are the periodic functions of their outer electronic configurations.' Verify that as you move across a period or down a group, properties of elements vary in a predictable way, which is influenced by their outer electronic configurations. This statement is true.

Analyze Statement 2

Statement 2 says that 'Non-metallic elements are lesser in number than metallic elements.' Generally, metallic elements are more abundant than non-metallic elements in the periodic table. This statement is true.

Analyze Statement 3

Statement 3 says that 'For transition elements the d-subshells are filled with electrons monotonically with increase in atomic number.' The filling of the d-subshell actually is not always monotonic and can vary due to electron configuration stability. This statement is not entirely correct.

Analyze Statement 4

Statement 4 says that 'In the periodic table metallic elements appear in the right-hand columns.' However, metallic elements are actually found on the left-hand side and the middle parts of the periodic table. This statement is false.

Identify the Incorrect Statement

Based on the analysis, the correct answer is the statement that incorrectly describes the periodic classification of elements. It is Statement 4.

Key concepts

periodic table

The periodic table is a comprehensive chart of all known chemical elements. It organizes these elements into rows called periods and columns known as groups. Each element is placed based on its atomic number, which is the number of protons found in the nucleus of an atom. This arrangement helps to predict the properties of elements and their compounds. Elements in the same group often share similar chemical behaviors because they have the same number of valence electrons.
For example, the noble gases in Group 18 all have full outer electron shells, which makes them very unreactive.

atomic number

The atomic number is a fundamental property of an element, denoted by the symbol Z. It represents the number of protons in the nucleus of an atom. Each element on the periodic table has a unique atomic number, distinguishing it from other elements. For instance, hydrogen has an atomic number of 1 because it has one proton, while carbon has an atomic number of 6 because it has six protons. The atomic number also determines the element's position on the periodic table in increasing order from left to right.

metallic elements

Metallic elements, also known as metals, are abundant on the left and middle parts of the periodic table. Metals are characterized by their ability to conduct electricity and heat, their shiny appearance, and their malleability and ductility. Most metals are solid at room temperature except for mercury. Examples of metallic elements include iron (Fe), gold (Au), and aluminum (Al).

• Conductivity: Metals are good conductors of electricity and heat.
• Malleability: Metals can be hammered into thin sheets.
• Ductility: Metals can be drawn into wires.

non-metallic elements

Non-metallic elements are found primarily on the right-hand side of the periodic table. These elements are generally poor conductors of heat and electricity, and they are not shiny. Non-metals can be gases, liquids, or solids at room temperature. Examples of non-metallic elements include oxygen (O), nitrogen (N), and sulfur (S).
Common properties of non-metals include:

• Poor conductivity: Non-metals are poor conductors of heat and electricity.
• Brittle: Non-metals are usually not malleable or ductile and can break easily when solid.
• Diverse states: Non-metals can exist in various states, such as gases (like chlorine), liquids (like bromine), or solids (like carbon).

electron configuration

Electron configuration describes the arrangement of electrons in an atom's orbitals. This configuration is crucial because it determines how an element will chemically react with others. The configuration follows the principles of the Aufbau principle, Hund’s rule, and the Pauli-exclusion principle. Electrons fill orbitals in a way that minimizes the energy of the atom. For instance, the electron configuration of carbon is 1s² 2s² 2p², showing it has six electrons distributed among its orbitals. Knowing an element's electron configuration helps to understand its place in the periodic table and its chemical properties.

---

• Aufbau principle: Electrons fill the lowest energy orbitals first.
• Hund's rule: Electrons occupy degenerate orbitals singly before pairing up.
• Pauli-exclusion principle: No two electrons can have the same set of quantum numbers in a single atom.