Question

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❕[Classification of elements]❕
❕❗❕< CLASS 11 >❕❗❕

Define :-
1) Atoms
2) Molecules
3) Compounds
4) Elements
5) Periods
6) Groups

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Answer 1

$<b><i>HLLO NIDHRA!!$

ATOMS:- An atom is the smallest particle of a chemical element that retains its chemical properties. 
Examples:- Electron, proton , neutron.
__________

MOLECULES:- The smallest unit into which a substance can be divided without changing its chemical nature.
Examples:-H2, N2, O2, Cl2 
__________

COMPOUNDS:- I think it is a mixture of molecules .
Examples:- Here is the best example of water .
It is a compound of two atoms hydrogen and oxygen.

___________

ELEMENTS:- In chemistry A chemical element is a substance that cannot be broken down by chemical means. Although elements aren't changed by chemical reactions, new elements may be formed by nuclear reactions.

___________

PERIODS:- A period is the name given to a horizontal row of the periodic table
Example:- Period 1 contains only two elements: hydrogen and helium.

___________

Groups:- It is is a column of elements in the periodic table of the chemical elements.
There are 18 numbers of groups in the periodic table.

1st group = alkali matels
2nd group = alkali earth matels.

HOPE IT HELPED YOU .

Answer 2

hai frnd
$classsificaton \: of \: elements \:$
are also know as division of elements:-
in a periodic table the elements are classified based on some properties ,principles,theries agter arranged in
a order in a table .

◆ there are 7 rows in a moder periodic table
◆each horizontal row is called a period in a periodic table
◆there are 18 columns in a modern periodic table .
◆each column is called a group
◆1st group elements are called alkali metals .
~these metals have the property of making bases
◆ 2nd group elements are called alkali earth metals
~because they are abundantly available on earth
◆16th group elements are called chalcogens
◆17th group elements are called halogens
◆19th group elements are called noble gases { or } zero group elements ,in active elements ,inert gases,stable elements .
◆18th group elements doesn't reach with other elements to form a compound.
● the 8th period i.e 1st period the main table is called lanthanide.
●the 9th period i e 2nd period below the mai. table is called actinides .
◆ elements of 1st and 2nd group combinly called as 's' block elements because when we write electronic configuration enters into 's' shell.
◆ elements from 13th to 18th group combinly called as 'p' block elements because ,when we write electronic configuration in to 'p' shell.
◆elements between s block nd p block are d block elements because when we write electronic configuration the last elements of configuration enters into d shell
lanthanide and actinides are f block elements because,when we write electronic configuration the last elements of configuration enters into f shell
◆◆s and p block elements combinly called representative elements◆◆
◆◆ d block elements are called transitional elements ◆◆
◆◆f block elements are called inner transition elements ◆◆
left side elements in periodic table ->metals except hydrogen
right side elements in periodic table -> non mentals .
◆●◆ATOMS◆●◆
atoms are small particles present o. the matter is called atoms
◆●◆MOLECULES◆●◆
molecule is the smallest particles of matter tht exists independently and is formed by the combination of atom .

◆●◆COMPOUNDS◆●◆
compound is a molecules made up of atoms
from different elements .




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