Selina Textbook Solutions: Chemical Bonding - Ionic Compounds and Covalent Compounds | Chemistry Class 10 ICSE PDF Download

 Page 1


Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
                   
INTEXT - QUESTION- 1 
 
Question 1: 
How do atoms attain noble gas configuration? 
Solution 1: 
Atoms lose, gain or share electrons to attain noble gas configuration  
 
 
Question 2: 
Define: 
(a) a chemical bond 
(b) an electrovalent bond 
(c) a covalent bond 
Solution 2: 
(a) A chemical bond may be defined as the force of attraction between any two atoms, in a 
molecule, to maintain stability. 
(b) The chemical bond formed between two atoms by transfer of one or more electrons from the 
atom of a metallic electropositive element to an atom of a non-metallic electronegative 
element. 
(c) The chemical bond formed due to mutual sharing of electrons between the given pairs of 
atoms of non-metallic elements. 
 
 
Question 3: 
What are the conditions for the formation of an electrovalent bond? 
Solution 3: 
Conditions for formation of Ionic bond are: 
(i) The atom which changes into cation should possess 1, 2 or 3 valency electrons. The other 
atom which changes into anion should possess 5, 6 or 7 electrons in the valence shell. 
(ii) A high difference of electronegativity of the two atoms is necessary for the formation of an 
Ionic bond. 
(iii) There must be an overall decrease in energy i.e., energy must be released. 
  For this an atom should have low value of Ionisation potential and the other atom   should 
have high value of electron affinity. 
(iv)  Higher the lattice energy, greater will be the case of forming an ionic compound. 
 
 
Question 4: 
An atom X has three electrons more than the noble gas configuration. What type of ion will it 
form? Write the formula of its  
 
Page 2


Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
                   
INTEXT - QUESTION- 1 
 
Question 1: 
How do atoms attain noble gas configuration? 
Solution 1: 
Atoms lose, gain or share electrons to attain noble gas configuration  
 
 
Question 2: 
Define: 
(a) a chemical bond 
(b) an electrovalent bond 
(c) a covalent bond 
Solution 2: 
(a) A chemical bond may be defined as the force of attraction between any two atoms, in a 
molecule, to maintain stability. 
(b) The chemical bond formed between two atoms by transfer of one or more electrons from the 
atom of a metallic electropositive element to an atom of a non-metallic electronegative 
element. 
(c) The chemical bond formed due to mutual sharing of electrons between the given pairs of 
atoms of non-metallic elements. 
 
 
Question 3: 
What are the conditions for the formation of an electrovalent bond? 
Solution 3: 
Conditions for formation of Ionic bond are: 
(i) The atom which changes into cation should possess 1, 2 or 3 valency electrons. The other 
atom which changes into anion should possess 5, 6 or 7 electrons in the valence shell. 
(ii) A high difference of electronegativity of the two atoms is necessary for the formation of an 
Ionic bond. 
(iii) There must be an overall decrease in energy i.e., energy must be released. 
  For this an atom should have low value of Ionisation potential and the other atom   should 
have high value of electron affinity. 
(iv)  Higher the lattice energy, greater will be the case of forming an ionic compound. 
 
 
Question 4: 
An atom X has three electrons more than the noble gas configuration. What type of ion will it 
form? Write the formula of its  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
(i) sulphate  
(ii) nitrate  
(iii) phosphate  
(iv) carbonate 
(v) hydroxide 
Solution 4: 
It will form a cation : M
3+
 
M2(SO4)3 
M(NO3)3 
M3(PO4)3 
M2(CO3)3 
M(OH)3  
 
 
Question 5: 
Mention the basic tendency of an atom which makes it to combine with other atoms. 
Solution 5: 
Atoms combine with other atoms to attain stable octet or noble gas configuration.  
 
 
Question 6: 
What type of compounds are usually formed between metals and non-metals and why? 
Solution 6: 
Ionic compounds are generally formed between metals and non-metals as metals always lose 
electrons to form cations while non-metals gain electrons forming anions to complete their octet. 
These oppositely charged ions are held together by electrostatic force of attraction and hence 
results in an ionic compound.  
 
 
Question 7: 
In the formation of the compound XY2, an atom X gives one electron to each Y atom. What is 
the nature of bond in XY2? Draw the electron dot structure of this compound. 
Solution 7: 
 
X and Y form an ionic bond in XY2. 
  
 
Page 3


Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
                   
INTEXT - QUESTION- 1 
 
Question 1: 
How do atoms attain noble gas configuration? 
Solution 1: 
Atoms lose, gain or share electrons to attain noble gas configuration  
 
 
Question 2: 
Define: 
(a) a chemical bond 
(b) an electrovalent bond 
(c) a covalent bond 
Solution 2: 
(a) A chemical bond may be defined as the force of attraction between any two atoms, in a 
molecule, to maintain stability. 
(b) The chemical bond formed between two atoms by transfer of one or more electrons from the 
atom of a metallic electropositive element to an atom of a non-metallic electronegative 
element. 
(c) The chemical bond formed due to mutual sharing of electrons between the given pairs of 
atoms of non-metallic elements. 
 
 
Question 3: 
What are the conditions for the formation of an electrovalent bond? 
Solution 3: 
Conditions for formation of Ionic bond are: 
(i) The atom which changes into cation should possess 1, 2 or 3 valency electrons. The other 
atom which changes into anion should possess 5, 6 or 7 electrons in the valence shell. 
(ii) A high difference of electronegativity of the two atoms is necessary for the formation of an 
Ionic bond. 
(iii) There must be an overall decrease in energy i.e., energy must be released. 
  For this an atom should have low value of Ionisation potential and the other atom   should 
have high value of electron affinity. 
(iv)  Higher the lattice energy, greater will be the case of forming an ionic compound. 
 
 
Question 4: 
An atom X has three electrons more than the noble gas configuration. What type of ion will it 
form? Write the formula of its  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
(i) sulphate  
(ii) nitrate  
(iii) phosphate  
(iv) carbonate 
(v) hydroxide 
Solution 4: 
It will form a cation : M
3+
 
M2(SO4)3 
M(NO3)3 
M3(PO4)3 
M2(CO3)3 
M(OH)3  
 
 
Question 5: 
Mention the basic tendency of an atom which makes it to combine with other atoms. 
Solution 5: 
Atoms combine with other atoms to attain stable octet or noble gas configuration.  
 
 
Question 6: 
What type of compounds are usually formed between metals and non-metals and why? 
Solution 6: 
Ionic compounds are generally formed between metals and non-metals as metals always lose 
electrons to form cations while non-metals gain electrons forming anions to complete their octet. 
These oppositely charged ions are held together by electrostatic force of attraction and hence 
results in an ionic compound.  
 
 
Question 7: 
In the formation of the compound XY2, an atom X gives one electron to each Y atom. What is 
the nature of bond in XY2? Draw the electron dot structure of this compound. 
Solution 7: 
 
X and Y form an ionic bond in XY2. 
  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
Question 8: 
An atom X has 2, 8, 7 electrons in its shell. It combines with Y having 1 electron in its outermost 
shell. 
(a) What type of bond will be formed between X and Y? 
(b) Write the formula of the compound formed. 
Solution 8: 
(a) X has 7 electrons in its outermost shell and Y has only one electron in its outermost shell 
so Y loses its one electron and X gains that electron to form an ionic bond. 
(b) The formula of the compound would be XY.  
 
 
Question 9: 
Draw orbit structure and electron dot diagram of NaCI, MgCl2 and CaO. 
Solution 9: 
 
Orbit structure and electron dot diagram of NaCl: 
 
 
Orbit structure and electron dot diagram of MgCl2: 
 
 
 
Orbit structure and electron dot diagram of CaO: 
Page 4


Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
                   
INTEXT - QUESTION- 1 
 
Question 1: 
How do atoms attain noble gas configuration? 
Solution 1: 
Atoms lose, gain or share electrons to attain noble gas configuration  
 
 
Question 2: 
Define: 
(a) a chemical bond 
(b) an electrovalent bond 
(c) a covalent bond 
Solution 2: 
(a) A chemical bond may be defined as the force of attraction between any two atoms, in a 
molecule, to maintain stability. 
(b) The chemical bond formed between two atoms by transfer of one or more electrons from the 
atom of a metallic electropositive element to an atom of a non-metallic electronegative 
element. 
(c) The chemical bond formed due to mutual sharing of electrons between the given pairs of 
atoms of non-metallic elements. 
 
 
Question 3: 
What are the conditions for the formation of an electrovalent bond? 
Solution 3: 
Conditions for formation of Ionic bond are: 
(i) The atom which changes into cation should possess 1, 2 or 3 valency electrons. The other 
atom which changes into anion should possess 5, 6 or 7 electrons in the valence shell. 
(ii) A high difference of electronegativity of the two atoms is necessary for the formation of an 
Ionic bond. 
(iii) There must be an overall decrease in energy i.e., energy must be released. 
  For this an atom should have low value of Ionisation potential and the other atom   should 
have high value of electron affinity. 
(iv)  Higher the lattice energy, greater will be the case of forming an ionic compound. 
 
 
Question 4: 
An atom X has three electrons more than the noble gas configuration. What type of ion will it 
form? Write the formula of its  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
(i) sulphate  
(ii) nitrate  
(iii) phosphate  
(iv) carbonate 
(v) hydroxide 
Solution 4: 
It will form a cation : M
3+
 
M2(SO4)3 
M(NO3)3 
M3(PO4)3 
M2(CO3)3 
M(OH)3  
 
 
Question 5: 
Mention the basic tendency of an atom which makes it to combine with other atoms. 
Solution 5: 
Atoms combine with other atoms to attain stable octet or noble gas configuration.  
 
 
Question 6: 
What type of compounds are usually formed between metals and non-metals and why? 
Solution 6: 
Ionic compounds are generally formed between metals and non-metals as metals always lose 
electrons to form cations while non-metals gain electrons forming anions to complete their octet. 
These oppositely charged ions are held together by electrostatic force of attraction and hence 
results in an ionic compound.  
 
 
Question 7: 
In the formation of the compound XY2, an atom X gives one electron to each Y atom. What is 
the nature of bond in XY2? Draw the electron dot structure of this compound. 
Solution 7: 
 
X and Y form an ionic bond in XY2. 
  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
Question 8: 
An atom X has 2, 8, 7 electrons in its shell. It combines with Y having 1 electron in its outermost 
shell. 
(a) What type of bond will be formed between X and Y? 
(b) Write the formula of the compound formed. 
Solution 8: 
(a) X has 7 electrons in its outermost shell and Y has only one electron in its outermost shell 
so Y loses its one electron and X gains that electron to form an ionic bond. 
(b) The formula of the compound would be XY.  
 
 
Question 9: 
Draw orbit structure and electron dot diagram of NaCI, MgCl2 and CaO. 
Solution 9: 
 
Orbit structure and electron dot diagram of NaCl: 
 
 
Orbit structure and electron dot diagram of MgCl2: 
 
 
 
Orbit structure and electron dot diagram of CaO: 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
 
  
 
 
Question 10: 
Compare: 
(a) sodium atom and sodium ion 
(b) chlorine atom and chloride ion, with respect to  
      (i) atomic structure 
      (ii) electrical state 
      (iii) chemical action 
      (iv) toxicity 
Solution 10: 
(a)   Sodium atom and sodium ion 
       (i) Sodium atom has one electron in M shell while sodium ion has 8 electrons in L shell. 
(ii) Sodium atom is neutral while sodium ion is positively charged. 
(iii) Sodium atom is highly reactive while its ion is inert. 
(iv) Sodium atom is poisonous while sodium ion is non-poisonous. 
 
(b)   Chlorine atom and chlorine ion 
(i) Chlorine atom has 7 electrons in its M shell while Chloride ion has 8 electrons in the 
same shell. 
(ii) Chlorine atom is neutral while chloride ion is negatively charged. 
(iii) Chlorine atom is highly reactive while its ion is inert. 
iv) Chlorine gas is poisonous while chloride ion is non-poisonous.  
 
 
 
 
Page 5


Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
                   
INTEXT - QUESTION- 1 
 
Question 1: 
How do atoms attain noble gas configuration? 
Solution 1: 
Atoms lose, gain or share electrons to attain noble gas configuration  
 
 
Question 2: 
Define: 
(a) a chemical bond 
(b) an electrovalent bond 
(c) a covalent bond 
Solution 2: 
(a) A chemical bond may be defined as the force of attraction between any two atoms, in a 
molecule, to maintain stability. 
(b) The chemical bond formed between two atoms by transfer of one or more electrons from the 
atom of a metallic electropositive element to an atom of a non-metallic electronegative 
element. 
(c) The chemical bond formed due to mutual sharing of electrons between the given pairs of 
atoms of non-metallic elements. 
 
 
Question 3: 
What are the conditions for the formation of an electrovalent bond? 
Solution 3: 
Conditions for formation of Ionic bond are: 
(i) The atom which changes into cation should possess 1, 2 or 3 valency electrons. The other 
atom which changes into anion should possess 5, 6 or 7 electrons in the valence shell. 
(ii) A high difference of electronegativity of the two atoms is necessary for the formation of an 
Ionic bond. 
(iii) There must be an overall decrease in energy i.e., energy must be released. 
  For this an atom should have low value of Ionisation potential and the other atom   should 
have high value of electron affinity. 
(iv)  Higher the lattice energy, greater will be the case of forming an ionic compound. 
 
 
Question 4: 
An atom X has three electrons more than the noble gas configuration. What type of ion will it 
form? Write the formula of its  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
(i) sulphate  
(ii) nitrate  
(iii) phosphate  
(iv) carbonate 
(v) hydroxide 
Solution 4: 
It will form a cation : M
3+
 
M2(SO4)3 
M(NO3)3 
M3(PO4)3 
M2(CO3)3 
M(OH)3  
 
 
Question 5: 
Mention the basic tendency of an atom which makes it to combine with other atoms. 
Solution 5: 
Atoms combine with other atoms to attain stable octet or noble gas configuration.  
 
 
Question 6: 
What type of compounds are usually formed between metals and non-metals and why? 
Solution 6: 
Ionic compounds are generally formed between metals and non-metals as metals always lose 
electrons to form cations while non-metals gain electrons forming anions to complete their octet. 
These oppositely charged ions are held together by electrostatic force of attraction and hence 
results in an ionic compound.  
 
 
Question 7: 
In the formation of the compound XY2, an atom X gives one electron to each Y atom. What is 
the nature of bond in XY2? Draw the electron dot structure of this compound. 
Solution 7: 
 
X and Y form an ionic bond in XY2. 
  
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
Question 8: 
An atom X has 2, 8, 7 electrons in its shell. It combines with Y having 1 electron in its outermost 
shell. 
(a) What type of bond will be formed between X and Y? 
(b) Write the formula of the compound formed. 
Solution 8: 
(a) X has 7 electrons in its outermost shell and Y has only one electron in its outermost shell 
so Y loses its one electron and X gains that electron to form an ionic bond. 
(b) The formula of the compound would be XY.  
 
 
Question 9: 
Draw orbit structure and electron dot diagram of NaCI, MgCl2 and CaO. 
Solution 9: 
 
Orbit structure and electron dot diagram of NaCl: 
 
 
Orbit structure and electron dot diagram of MgCl2: 
 
 
 
Orbit structure and electron dot diagram of CaO: 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
 
  
 
 
Question 10: 
Compare: 
(a) sodium atom and sodium ion 
(b) chlorine atom and chloride ion, with respect to  
      (i) atomic structure 
      (ii) electrical state 
      (iii) chemical action 
      (iv) toxicity 
Solution 10: 
(a)   Sodium atom and sodium ion 
       (i) Sodium atom has one electron in M shell while sodium ion has 8 electrons in L shell. 
(ii) Sodium atom is neutral while sodium ion is positively charged. 
(iii) Sodium atom is highly reactive while its ion is inert. 
(iv) Sodium atom is poisonous while sodium ion is non-poisonous. 
 
(b)   Chlorine atom and chlorine ion 
(i) Chlorine atom has 7 electrons in its M shell while Chloride ion has 8 electrons in the 
same shell. 
(ii) Chlorine atom is neutral while chloride ion is negatively charged. 
(iii) Chlorine atom is highly reactive while its ion is inert. 
iv) Chlorine gas is poisonous while chloride ion is non-poisonous.  
 
 
 
 
Class X Chapter 2 – Chemical Bonding  Chemistry 
_____________________________________________________________________________ 
 
Question 11: 
The electronic configuration of fluoride ion is the same as that of a neon atom. What is the 
difference between the two? 
Solution 11: 
Fluoride ion is negatively charged while neon atom is neutral.  
 
INTEXT - QUESTION- 2 
 
Question 1: 
What are the conditions necessary for the formation of covalent molecules? 
Solution 1: 
(i) Both atoms should have four or more electrons in their outermost shells, i.e., non-metals. 
(ii) Both the atoms should have high electronegativity. 
(iii) Both the atoms should have high electron affinity and high ionisation potential. 
(iv) Electronegativity difference between the two atoms should be zero or negligible. 
(v) The approach of the atoms towards one another should be accompanied by decrease of 
energy.  
 
 
Question 2: 
Elements A, B and C have atomic number 17, 19 and 10 respectively. 
(a) State which one is: (i) a non-metal (ii) a metal, (iii) chemically inert? 
(b) write down the formula of the compound formed by two of the above elements. 
Solution 2: 
(a) A is a non-metal; B is a metal while C is a chemically inert element. 
(b) BA 
 
 
Question 3: 
Five atoms are labelled from A to E. 
Atoms Mass No. Atomic No. 
A 40 20 
B 19 9 
C 7 3 
D 16 8 
E 14 7 
 
(a) Which one of these atoms: 
     (i) contains 7 protons, 
     (ii) has an electronic configuration 2, 7? 
(b) Write down the formula of the compound formed between C and D. 
(c) predict which are: (i) metals, (ii) non-metals?