notes for ICSE Class 9th chemistry chapter periodic table topic Modern Periodic Table
Answers
Answer:
Henry Mosley put forward the *modern periodic table*. which was based on atomic number. He stated that "the physical and chemical properties of elements are the periodic functions of their atomic ynumber.
Definition: *A tabular arrangement of elements in groups and periods highlighting the regular trends in properties of elements is called a PERIODIC TABLE.
GROUP:
The modern periodic table has 18 vertical columns called groups.
GROUP 1 : These elements are known as Alkali metals as they form strong alkalia with water.
GROUP2: Alkaline earth metals- they form weaker alkali as compared to group 1.
GROUP 3,4,5,6,7,8,9,19,11 and 13 are known as *transition elements.
GROUP 13: Boron family
GROUP 14: Carbon family
GROUP 15: Nitrogen family
GROUP 16: Oxyfen family or chalcogens, maning ore forming .
GROUO 17: Halogens
GROUO 18 Inert gases.
*PERIODICITY*
The properties that reappear at regular intervals or in which there is gradual variation at regular intervals, are called 'periodic properties' and the phenomenon is called periodicity.
ORBITS
ectrons revolve around the nucleus in certain definite circular paths.
VALENCY
(i dont remember its definition)
(Sorry)
answer:-
valency - no.of valence electrons in the outermost shell.
Explanation:
for eg:- sodium. sodium has atomic no. 11 and the electronic configuration is 2,8,1 . sodium has 1 electron in outermost shell so it's valency is 1