Problem 1 - A Complete Resource Book in Chemistry for JEE Main

Question

How many e \(^{-}\)are present in p-sub-orbits in \(\mathrm{Zn}\)-atom? (a) 2 (b) 6 (c) 12 (d) 18

Step-by-Step Solution

Answer

The Zn atom has 12 electrons in p-sub-orbitals.

Step 1: Understand the Electronic Configuration

The atomic number of zinc (Zn) is 30. The electronic configuration of a Zn atom is determined based on its 30 electrons. The configuration is: \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 3d^{10} \).

Step 2: Identify p-sub-orbitals

In the electron configuration, the 'p' sub-orbitals are present in the 2p and 3p levels. The configurations for these are \( 2p^6 \) and \( 3p^6 \).

Step 3: Count Electrons in p-sub-orbitals

Each p-sub-orbital can hold 6 electrons (\( p^6 \)). Given there are 2 p-sub-orbitals: \( 2p^6 \) and \( 3p^6 \), each contains 6 electrons. Sum them: \( 6 + 6 = 12 \).

Key Concepts

Zinc Atom

The zinc atom is an essential concept in chemistry, as it helps us understand electronic configuration and atomic structure. Zinc, represented by the symbol \( \text{Zn} \), is a transition metal that is well-known for its use in galvanizing and alloys. It is the 30th element on the periodic table. The atomic structure of zinc includes 30 protons in its nucleus, which determines its atomic number. Surrounding the nucleus are electrons arranged in specific energy levels or shells. This unique structure gives zinc its characteristic properties. By understanding the arrangement of electrons in a zinc atom, we can predict its chemical behavior and bonding capabilities.

P-Sub-Orbitals

In the realm of electronic configuration, p-sub-orbitals hold particular significance. Orbitals are regions around the nucleus where electrons are likely to be found. Each principal energy level can have one or more sub-levels, which include s, p, d, and f orbitals. The p-sub-orbitals, in particular, are shaped like dumbbells and exist in groups of three at each principal energy level beginning from the second shell. Each set of p-sub-orbitals can accommodate up to six electrons \( (p^6) \), two per orbital. When examining the electron configuration of an element, identifying the electrons in the p-sub-orbitals gives insights into its reactivity and bond formation.

Electron Counting

Electron counting is a vital step in understanding the electronic configuration of atoms. It involves determining the number of electrons in various orbitals based on the element's atomic number. For zinc with an atomic number of 30, electron counting helps us understand how these electrons occupy the different orbitals: \(1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^{10}\). Here, we specifically focus on how these 30 electrons are distributed to achieve the most stable configuration. Knowing how to count electrons correctly is essential for predicting the chemical and physical properties of elements.

Atomic Number

The concept of the atomic number is fundamental to chemistry and physics. It is defined as the number of protons in the nucleus of an atom, which also equals the number of electrons in a neutral atom, thereby determining the element's identity. For zinc, the atomic number is 30. This number is crucial as it tells us not only how electrons should be arranged in an atom but also an element's location on the periodic table. Furthermore, atomic number influences atomic size, electronegativity, and even an element's reactivity. Understanding atomic numbers thus provides a framework for exploring the periodic table and predicting the properties of elements.