Class 11 Chemistry - MP
Classification of Elements and Periodicity in Properties
The chapter 'Classification of Elements and Periodicity in Properties' in Class 11 Chemistry explores the historical attempts to organize elements and introduces the modern periodic table based on atomic numbers. Students learn how electronic configurations dictate periodicity and study periodic trends such as atomic radius, ionic radius, ionization enthalpy, electron gain enthalpy, and electronegativity. This chapter is foundational for understanding chemical bonding and reactivity, making it highly important for MPBSE board exams where conceptual reasoning and trend-based questions frequently appear.
Start Learning FreeKey Concepts
Modern Periodic Law
The physical and chemical properties of elements are periodic functions of their atomic numbers.
Atomic and Ionic Radius
Atomic radius generally decreases across a period due to increased effective nuclear charge and increases down a group due to the addition of new shell levels.
Ionization Enthalpy
It is the energy required to remove an electron from an isolated gaseous atom, increasing across a period and decreasing down a group.
Electron Gain Enthalpy
The enthalpy change when an electron is added to a gaseous neutral atom, becoming more negative across a period and less negative down a group.
Electronegativity
The tendency of an atom to attract shared electrons in a covalent bond, increasing across periods and decreasing down groups.
Important Formulas
Board Exam Info
In the Madhya Pradesh (MPBSE) Class 11 Chemistry examination, this chapter typically carries around 4 to 6 marks. Questions usually include objective type (MCQs/fill-in-the-blanks), short-answer reasoning questions about periodic trends (e.g., why size decreases across a period or why noble gases have positive electron gain enthalpy), and IUPAC nomenclature for elements with atomic numbers greater than 100.
Frequently Asked Questions
Why is the electron gain enthalpy of noble gases positive?
Noble gases have fully filled stable electronic configurations, so adding an extra electron requires energy, making the electron gain enthalpy positive.
Why does atomic radius decrease across a period?
As we move across a period, the atomic number increases, adding protons to the nucleus which increases the nuclear charge and pulls the electrons closer, thereby decreasing the size.
What is the IUPAC name for an element with atomic number 105?
Using IUPAC roots (1=un, 0=nil, 5=pent), the name is Unnilpentium (Unp).
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