Class 10 Science - ICSE-CHEMISTRY
Periodic Table, Periodic Properties and Variations
This chapter explores the modern periodic table, tracing its evolution from Dobereiner's triads and Newlands' octaves to Mendeleev's table and finally the Modern Periodic Law. Students learn how elements are arranged in periods and groups based on atomic number. A major focus is placed on periodic properties such as valency, atomic size, metallic character, ionization energy, electron affinity, and electronegativity, along with their predictable trends down a group and across a period. This high-weightage ICSE Chemistry chapter builds the foundational chemical reasoning required for predicting element behavior and solving board exam equations.
Start Learning FreeKey Concepts
Modern Periodic Law
The physical and chemical properties of elements are a periodic function of their atomic numbers.
Periodicity
The repetition of similar properties of elements at regular intervals when arranged in order of increasing atomic number.
Atomic Size
The distance between the center of the nucleus and the outermost shell of an isolated atom; decreases across a period and increases down a group.
Ionization Energy
The amount of energy required to remove an electron from a neutral gaseous isolated atom; increases across a period and decreases down a group.
Electron Affinity
The amount of energy released when an electron is added to a neutral gaseous atom; increases across a period and decreases down a group.
Electronegativity
The tendency of an atom to share electrons in a covalent bond to attract electrons towards itself; increases across a period and decreases down a group.
Important Formulas
Board Exam Info
In the ICSE Chemistry Class 10 Board Exam, this chapter typically carries around 8 to 12 marks. Common question types include reasoning questions based on periodic trends, identifying elements based on group and period numbers, and explaining anomalies in properties.
Frequently Asked Questions
Why does atomic size decrease as we move from left to right across a period?
Because the nuclear charge increases while the number of shells remains the same, pulling the electrons closer to the nucleus.
Why do noble gases have zero electron affinity?
Because they have a stable, completely filled valence electron shell and do not have a tendency to accept extra electrons.
How do metallic and non-metallic characters vary across a period?
Metallic character decreases from left to right across a period, while non-metallic character increases.
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