Any icse student of class 10th online yet I need there help urgent.
Can they provide me 1st chp of chemistry note in. A
SHORT SUMMARY.
PLZ N OK SPARM TOMMROW IS MY EXAM.
ONLY THOSE WHO NO THEY ONLY ANSWER IT.
Answers
The first chapter is Periodic table .
Short Summary
The Modern Periodic Table is a table where elements are arranged in increasing order of their atomic numbers .
Earlier scientists tried to classify elements on the basis of atomic weights .
Notable mentions are Doberneir's law of Triads , Law of Octaves , etc .
The Modern Periodic Table
Basics :
Periods are horizontal rows .
Groups are vertical columns .
Elements show periodicity in properties or occurrence in properties at regular intervals . The properties are called periodic properties .
Some periodic properties are :
Atomic radius : The distance between the centre of an atom and the outermost shell .
Electron affinity , Ionisation potential .
Electronegativity is the tendency of an element to attract shared pairs of electrons when combined in compound .
The properties tend to change at regular intervals throughout the table when elements are arranged in increasing order of their atomic numbers .
Change of properties ( Trends )
From left to right across a period :
→ Atomic radius decreases .
→ Nuclear charge increases .
→ Ionization potential increases .
→ Electron affinity increases .
→ Metallic character decreases .
→ Electronegativity increases .
→ Non metallic character increases .
From top to down in a group :
→ Atomic radius increases
→ Nuclear charge decreases
→ Ionization potential decreases
→ Electron affinity decreases
→ Metallic character increases
→ Electronegativity decreases .
→ Non metallic character decreases .
NOTE :
In a group , number of valence electrons remains same .
In a period , number of shells remain same .
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