Problem 3 - A Complete Resource Book in Chemistry for JEE Main

Question

The number of electrons, neutrons and protons in a species are equal to 10,8 and 8 respectively. The proper symbol of the species is (a) \({ }^{16} \mathrm{O}_{8}\) (b) \({ }^{18} \mathrm{O}_{8}\) (c) \({ }^{18} \mathrm{Ne}_{10}\) (d) \({ }^{16} \mathrm{O}_{8}^{-2}\)

Step-by-Step Solution

Answer

The proper symbol of the species is \\({ }^{16} \mathrm{O}_{8}^{-2}\\).

Step 1: Identify Number of Protons

The number of protons defines the atomic number of an element. In this problem, the species has 8 protons, which corresponds to the element Oxygen (O) as per the periodic table.

Step 2: Determine the Element's Symbol

Given that the element with 8 protons is Oxygen, we start by looking at options that have the oxygen symbol (O) in them. Options (a), (b), and (d) present oxygen as a component, indicating these could be correct.

Step 3: Calculate Atomic Mass

The atomic mass of the species is the sum of protons and neutrons. Since there are 8 protons and 8 neutrons, the atomic mass is 8 + 8 = 16.

Step 4: Determine the Charge

The species has 10 electrons and 8 protons. Since electrons are negatively charged, having more electrons than protons results in an overall negative charge. Thus, there are 2 extra electrons, resulting in a charge of -2.

Step 5: Match the Configuration to Options

With an atomic mass of 16, atomic number 8, and -2 charge, we compare with the given options. Option (d), \( { }^{16} \mathrm{O}_{8}^{-2} \), matches our calculated values.

Key Concepts

Atomic Number

The atomic number is a fundamental property of an element that is incredibly important for understanding chemical species. It is defined as the number of protons found in the nucleus of an atom. Each element has a unique atomic number, which determines its identity on the periodic table.
This concept is crucial because it explains why elements behave differently from each other. For instance, in the original exercise, the species has 8 protons, giving it an atomic number of 8. This number corresponds to the element Oxygen (O).
Knowing the atomic number allows us to identify an element's position on the periodic table. Since the atomic number determines the element's identity, any variation in protons signifies a different element. Hence, correctly identifying the atomic number is the first step in identifying a chemical species.

Atomic Mass

Atomic mass, sometimes called atomic weight, is the total mass of an atom. It is calculated as the sum of the number of protons and neutrons in the nucleus. Unlike the atomic number, which is unique to each element, the atomic mass can vary even within atoms of the same element because of isotopes.
In this exercise, the atoms of the species were found to have 8 protons and 8 neutrons, giving them an atomic mass of 16 (8 protons + 8 neutrons = 16).
Understanding this concept helps to distinguish between different isotopes of the same element. For example, Oxygen-16 and Oxygen-18 are isotopes of oxygen. Their difference lies in the number of neutrons, which alters the atomic mass but not the elemental identity. This distinction is essential for applications in nuclear chemistry and physics, providing insight into atomic stability and reactions.

Protons, Neutrons, Electrons

Atoms are composed of three main subatomic particles: protons, neutrons, and electrons. Each of these plays a vital role in defining the properties and behavior of the atom.

• Protons: These positively charged particles are located in the atom's nucleus and determine the atomic number and identity of the element.
• Neutrons: Neutral particles also found in the nucleus. They contribute to the atomic mass and can affect the stability and isotopic nature of elements.
• Electrons: Negatively charged particles that orbit the nucleus in various energy levels, playing a crucial role in chemical reactivity and bonding.

In the exercise, the species contains 8 protons, 8 neutrons, and 10 electrons. The equal number of protons and neutrons provides a stable atomic structure, while the additional electrons give the atom an overall negative charge of -2.
This arrangement of subatomic particles highlights the importance of balancing charges and understanding the role of each particle in determining atomic makeup and its implications on chemical behavior.