Class 9 Science Chapter 14 Atomic Structure and Chemical bond Notes

1. Describe valency.
=Valency is a measurement of an atom's ability to combine with other atoms in an element to create molecules or valency compounds.




2. How would you express the valency of aluminum and nitrate in Al(NO))?

= Aluminum and nitrate have no valency in Al(NO).




3. How many electron pairs does the molecule of oxygen share?




The oxygen molecule shares two electron pair.




4. Fluorine has a valency of 1.
What electron makes up its valence?




= The valence electron for fluorine is 7.




6. Describe an element.




= A pure material with just one type of atom makes up an element.




7. What exactly is a compound?

=An impure substance that has more than two different types of atoms is called a compounds.

8.Write the subatomic particles it an atom.

= The subatomic particles of an atom are:

a.Electron

b.Proton

c.Neutron

9. What exactly is a covalent compound?




→The chemical compounds/ molecules termed by covalent bonding are called covalent compound.




10. Can you name any two electrovalent compounds?




= The two electro-valent compounds are as follows:




a.Cloride of Soda (NaCl)




Lithium Carbonate b. (Li2CO3)




11.What is meant by sodium's atomic mass?




=Atomic mass at sodium is 23, which is the sum of protons and neutrons in a sodium atom.




#. Questions requiring lengthy responses.




1.Write the valency of the ions and elements listed below.




NH4+ has the valency = CO2-- =2. Valency +1




PO3--- =3 valency 1 valency = CI




1 valency = Na Ca has a valency of two.




H has a valency of one. Valency of Al = 3




OH-1 valency = Si




valency Hg (ic) = OH = -1




O has a valency of two and NO3 has a valency of one.




b. Atom X loses two electrons in two atoms.

a. Water is the only solvent for the chemical.

b. when the compound is molten or dissolved in water it will conduct electricity

3.What do you understand by valence electors. and valence shell?

=An atom consist at various shells in which different numbers of electrons are located The outermort. shell of an atom is called a valence shell. The electrons present in the valence shell of an atom are called valence electrons.

4. Justify the statement "Nuclear energy is harmful as well as useful".

= The beneficial effects of nuclear energy is usually. overlooked because at its potentially devasting side effects. Nuclear waste can be extremely hazardous because at its high emissions of radiation, but health problems from this can be prevented with careful disposal it nuclear waste.

5.What is an electrovalent bond? Also give and example.

= The chemical bond Formed by the transfer of electrons from the valence shell at one atom to the valence shell of another atom is called electrovalent bond. ex: CaCl₂, etc..

7. Ditterentiate between duplet and octed.

Duplet Octet

a.It has two electrons in the outermost shell. a.lt has eight electron in the L outemost shell.

b.It has ns2 type configuration at the end. b. It has not no type election. contiguration at the end.

c.It has only one orbital. ! c. It may have a minimum of two orbitals.

d.It has only S orbital. d. It have all types it rebited (such as s, p, d, and f

g. What is a covalent bond? How is it formed? Explain. with an example.

= The chemical bond that is formed by the mutual sharing of electrons between the atoms each contributing equal number of electrons to the electron pairs is called a covalent bond. a covalent bond is farmed when the difference between the electronegativities of two atoms is to small for an electron transfer to occur to forms lons. ex H, O₂, N. etc.