Classification of elements best note

 Mention the place of non-metals in periodic table and write down their names.

Non-metal are placed at the right hand side of the periodic table from group ''VA'' to '0'.

They are N,O,F,P,S,CL,Se,Br, I,At (Astatine) and 'o' Group elements.

What are metalliods? Name any 3 metalliods.

Elements which lie between metal and nonmetal of the periodic table and possess both the metallic and non metallic character are called metalliods.

Silicon (Si), germanium (Ge), and bismuth
(Bi)

Why the elements of group IA are called alkali metal?

The metallic oxide of the metal of group IA dissolves in water to form alkali. So they are called alkali metal.

Why the elements of group IIA are called alkali earth metal?

The metallic oxide of the metal of group IA dissolves in water to form alkali, further their oxides and carbonates are abundantly present on the earth crust. So they are called alkali earth metal.

Why the properties of elements of one group of periodic table are similar?

Elements of same group of periodic table contains same number of electrons in the outer most orbits of their atoms due to similar electronic configuration. Therefore they have similar chemical and physical properties.

Why the properties of the elements of different group of periodic table are different?

Elements of different group of periodic table contain different number of electrons in the outer most orbit of their atom. Therefore they have different chemical and physical properties.

Why the properties of the elements of different group of periodic table are different?

Elements of diffrent group of periodic table contain different number of electrons in the outer most orbit of their atom. Therefore they have different chemical and physical properties because these electrons are responsible to take part in the chemical reaction.

Why the elements of group IA of periodic table are known as highly reactive metals?

Except hydrogen; lithium, sodium, potassium etc. of first group of periodic table are metals. They have only one electron in the outermost orbit  of the atoms. So they react easily and quickly with other elements by the donation of one electron of their outermost orbits.Therefore they are called highly reactive metals.

Why the elements of group VIIA of periodic table are known as highly reactive nonmetal?

Fluorine,chlorine,bromine,iodine etc.of group -VII of periodic table are nonmetals and their atoms contain 7 electrons in the outermost orbit. So they react easily and quickly with other elements by sharing electrons or by accepting one electron. Therefore the elements of group VII of periodic table is known as highly reactive nonmetals.

Why the elements  of group '0'of  periodic table are knows as insert gases?

Helium,Neon, Argon, Krypton etc. of 'Group-0' of the periodic table are gases. Their outermost orbit is fulfilled with the electrons either by 8 electrons (octet) or by 2 electrons (duplet).Since an element takes part in chemical reaction to complete the number of electrons in their outer most orbits,therefore they do not react with other elements and are known as insert gas.

Write down characteristics of modern (new)periodic table.

1. Elements are divided into 9 groups (18 columns ) and 7 periods (rows).

2. Landthanides and actinides are placed differently at the bottom of the periodic table.

3. Elements are divided not only into the groups and periods but they are also divided into 4 distinct blocks i.e.s,p,d and f-block elements.

4. Elements of Gr-VIII of old periodic table like Fe,Co,Ni,etc.are taken as transition elements and are placed in the order of transition elements between Gr.II A and IIIA.

5. Elements are arranged in the order of their increasing atomic number from left to right of the table.

What are  representative elements?

Elements of group -IA,IIA,IIIA,IVA,VA,and VIIA are called representative elements in which the outerost orbit of the atoms are not fullfilled with the number of electrons. They are s-block and p-block elements except noble gasses.

_{Why hydrogen is placed in group IA of periodic table?}

Like Li,Na,K etc of Gr-I of periodic table, hydrogen also reacts with halogens (flurione,chlorine etc) as an electropositive elements .

Hydrogen can be placed in group VIIA of periodic table?Why?

Following are the reasons:

i) It is a gas at the ordinary temperature like some halogens of group -VIIA of periodic table.

ii) Like halogens,its molecule its diatomic.

iii) Metals form halides with the halogens like NaCl,KBr etc .and similarly some metals form hydrides with hydrogen e.g. NaH,KH,CaH₂ etc.

iv) If it were placed in 'Group-VIIA'' there would not be a blank space for six elements between hydrogen and helium.

Why the elements of Group-VIIA of periodic table are known as halogens.

'Hale' means 'sea-salts' and 'genes' means 'produce'. So, halogen means sea-salt producer.This name is given to the elements of Gr-VIIA (F,Cl,Br etc.) of periodic table because chlorine produce sea-salt i.e. sodium chloride and other elements have also the tendency to form salts.

Why ''Alkali metals'' are placed in 'Group-IA' of periodic table.What is transition element?

The elemlent which lies in between highly reactive metals and nonmetals i.e. from group IIIB to IIB of periodic table are called transition elements.

Why transition metals have variable valency?

In case of transition metals,both the outermost and inner shells are not f'ulfilled with the electrons.Some times, only the electrons of the outermost orbit and some times the electrons of the inner orbit also take part in chemical reaction so their valency differ according to the number of electron that take part in chemical reaction.

What are landthanides and actinides?

After the element Lanthanum (At.No.-57), a series of 14 elements i.e. 'Cerium'(At.No.-58) to Lutetium (At.No.-71) and after Actinium (At.No.-89) another series of 14 elements i.e.Thorium (At.No.-90) to Lawrencium(At.No.-103) are called landthanides and Actinides respectively.

( In both the series their f-sub shell is being filled with electrons  so they are knowns as f-block elements and are placed at the bottom of the periodic table. They are also known as inner transition element.)

What are duplet and octet?

The condition of the elements having capacity to hold maximum two electrons in the outermost orbit of its atom is known as duplet.

The condition of the element having capacity to hold maximum eight electrons in the outermost orbit of its atom is known as octet.

What do you mean by 2n² rule of electron configuration?

It is a rule that gives the maximum number of electrons that an orbit of the atom can hold. Here 'n' represents number of orbit. According to this rule first orbit, 2nd orbit and 3rd orbit can hold 2,8,and 18 electrons respectively.

First orbit (n=1)

2n² = 2*1² =2*1=2

Second orbit (n=2)

2n²=2*2²=2*4=8

Write down the maximum number of electron that can stay in s,p,d and f sub-shells.

sub-shell                                                             No.Of electrons

s                                                                                   2

p                                                                                  6

d                                                                                  10

f                                                                                   14

Why landthanide and actinide are placed in different place in modern periodic table?

They have totally different properties than other elements of periodic table. They are characterized by the electrons being filled up in 'f ' orbital of forth orbit in case of Landthaide and 'f ' orbital of fith orbit in case of Actinides. Their property depends upon the number of electrons in 'f ' orbital. Therefore they are kept differently than other elements i.e. at the bottom of the periodic table.

What is s-block and p-block element?

Elements in which last electron enters into the s-sub shell of the outermost shell of their atom is called s-block element. Elements of group IA and IIA are s-block element.

Elements in which last electron enters into the p-sub shell of the outermost shell of their atom is called p-block element. Elements of group IIIA,IVA,VA,VIA,VIIA and '0' are called p-block element.

What are d-block and f-block element?

Elements in which the last electron enters into d-sub shell of their penultimate shell are called d-block elements.  Elements of group IIIB,IVB,VB,VIB,VIIB,IB and IIB are d-block elements.

Elements in which the last electron enters into f-sub shell of their anti-penultimate shell are called f-block element. Landthanides and actinides are f-block element.

Write down any two differences between s-block and p-block element.

s-block element	p-block element
1) Last electron enters into s-sub shell of their atom.	1) Last electron enters into p-sub shell of thier atom.
2) They lie in group-IA &IIA of periodic table.	2) They lie in group IIIA,IVA,VA,VIA,VIIA and 0 of periodic table.

Write down any three differences between d-block and f-block element.

d-block element	f-block element
1) Last electron enters into d-sub shell of penultimate shell.	1) Last electron enters into f-sub shell of antepenultimate shell.
2) They are  arranged in the middle part of the periodic table.	2) They are placed at the bottom part of the periodic table.
3) They are comaparatively more in number than f-block element.	3) They are only 28 which are comparatively less than d-block element.

What is Aufbau principle?

This principle expresses how electrons are filled in different sub shell.  According to this principle, electrons are filled in the sub shell from lower energy level to higher energy level. And the order of filling of sub shell is represented by following way:

What is noble gas?

Elements of 'Group 0' of periodic table i.e helium, neon, argon, krypton, xenon and radon are called noble gases because their outermost orbit is fulfilled with number of electrons either by eight electrons (octet) or by two electrons (duplet). So they do not take part in the chemical reaction and are called noble (or inert)gases.

What are halogens?

Elements of 'GroupVII  A' of periodic table are called halogens. They are fluorine, chlorine, bromine, iodine etc.

How are elements arranged in modern periodic table?

In modern periodic table, elements are arranged in the increasing order of atomic number from left to right in such a way that the elements having similar electronic configuration are in the same group.

What do you mean by metallic and non-metallic character of an element in a chemical reaction?

If an element reacts with another by donating electron then that character is called metallic character, but if it gains electrons then it is called non-metallic character.

What would be the effect on metallic character:

i) As we move from left to right in a period of periodic table.

When we move in a period from left to right, atomic radius goes on decreasing from 'Group-I' to 'Group-VII'. If an atom has greater radius, the attraction between the proton and the electron of outermost orbit becomes less. So, in a chemical reaction, the tendency to lose the electron/ s from the outermost orbit of the atom decreases. Tendency of loss of electron is metallic character. Therefore, metallic character gradually decreases due to the decrease of atomic radius as we move from left to right in a period.

ii) When we move down in a group of P.T.

As we move down in a periodic table, atomic radius of elements gradually increases due to the increase in number of orbits. Now the force of attraction between the proton and the electrons of the outermost orbit decreases . So they tendency of losing electrons in the chemical reactions i.e. the metallic characteristic increases.