Chemical Bonding2016

GSCIENCE CLASSES

CHEMICAL BONDING

1

What is a molecule? The smallest particle of an element or compound that is capable of an independent existence and shows all the properties of the substance is called a molecule. Q2 What is a chemical bond? Ans When atoms of elements combine to form molecules a force of attraction is developed between the combining atoms which holds them together .This force is called chemical bond. Q3 What are the different types of molecules? Give one example of each. Ans Molecules of an element: Molecules of an element is composed of atoms of the same kind. Eg: A molecule of hydrogen consists of two atoms of hydrogen Molecules of compound: Atoms of different elements combine together definite proportions to form molecules of compound. Eg: hydrogen chloride is a compound whose molecules are made up of one atom of hydrogen and one atom of chlorine. Q4 Why do atoms form bonds? Ans Atoms form bonds to become energetically favourable and lead to a minimum energy . Q5 What is octet? Ans Eight electrons in the outermost shell is called octet of an electrons. Q6 What is duplet? Ans Two electrons in the outermost shell of helium is called is called duplet. Q7 State Octet rule. Ans The principle of attaining eight electrons in the valence shell of atoms is called octet rule. Q8 What is electronic theory of valency? Ans According to Electronic theory of valency, atoms combine to acquire the nearest noble gas electronic configuration by losing, gaining or sharing electrons .This lead to the formation of chemical bonds between the combining atoms. Q9 Explain why Argon atom is stable? Ans The electronic configuration of Argon atom is 2,8,8. Since its outermost shell has eight electrons, this atom is stable. Q.10 Why is hydrogen molecule generally diatomic and not monoatomic? 2000 Ans: The atomic no. of hydrogen is 1.Therefore, its electronic configuration is 1. It is required 1 electron more to get stable configuration or duplet. The only means is to combine two hydrogen atoms.Hence, hydrogen is diatomic in nature. Q11 Why is the element with atomic numbers 10 stable? Ans The electronic configuration of the element is 2, 8.Thus, this element attain its octet and become stable. Page

Q1 Ans

Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

2

Why do elements other than noble gas combine to form molecules? What type of chemical bonding is expected when atom of hydrogen combines with an atom of chlorine? Ans Because these elements combine with other atom so as to get stable configuration of its nearest inert gas. When an atom of hydrogen combines with an atom of chlorine, the type of chemical bond expected is ‘covalent’ or ‘electrovalent’ bonding Q13 How do atoms combine together to form molecules? Ans All atoms other than noble gases have less than eight electrons in their outermost shells. So, the outermost shells of atoms of these elements do not have stable configurations. Therefore, they combine with each other or with other atoms to acquire stable nearest noble gas electronic configuration Q14 What are the ways by which an atom acquires the electronic configuration of the nearest inert elements. Or How can an atom of an element acquire stable electronic configuration? Or write the conditions for the formation chemical bond. Ans The two ways by which an atom acquires the electronic configurations of the inert gas are given below: a) By transference of valence electron or electrons from an atom to another enabling in the formation of electrovalent or ionic bond. E.g: NaCl b) By sharing of electrons between the bonded atoms or sharing of valence electrons of atom with other atoms resulting in the formation of covalent bonds. E.g: H2 ELECTROVALENT OR IONIC BOND Q15 What is electrovalent or ionic bond? Ans The type of combination between atoms which depend upon the transfer of electrons and in which oppositely charge ions are held together by electrostatic force of attraction is called electrovalent or ionic bond. Q16 What is electrovalency of atom? Ans The number of electrons lost or gained by an atom to attain the stable electronic configuration is known as the electrovalency of the atom. Q17 What is an electrovalent compound? Ans A compound which contains electrovalent bond formed by transfer of one or more electrons is known as an electrovalent compound. Q18 Give any three characteristics of Ionic or electrovalent compounds. Ans The characteristic properties are as follows: a. Ionic compounds are generally crystalline in nature b. Ionic compounds have high melting and boiling points. c. They conduct electricity in molten state and in their aqueous solution. Page

Q 12

Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING Page

3

Q19 How is an electrovalent bond or ionic formed? Ans An ionic or electrovalent bond is formed by the transfer of one or more electrons from one atom to another to attain the stable noble gas configuration. Q20 Describe the formation of NaCl molecule from its elements. Ans When sodium and chlorine react together, the outer electron of the sodium atom is transferred to the chlorine atom to produce sodium ion Na+ and chloride ion Cl-. The two ions (Na+, Cl-), being oppositely charged, are now held together by the electrostatic forces of attraction. Since both sorts of atoms attain a very stable inert gas configuration, the process is energetically favourable and sodium chloride, Na+Cl- is formed. .Q21 ( 2014) Sodium atom loses an electron to form sodium ion. Identify the compound form by sodium ion with another ion having the same number of electrons. Predict the solubility of the compound. 2 marks Ans: Ionic compound (i.e.Sodium chloride). The ionic compounds are soluble in water and other polar solvents . Q22 Explain the formation of MgCl from its elements. Ans The electronic configuration of Mg ( at. No. ) is 2,8,2.It has 2 electrons in its outermost shell. Thus the Mg atom transfers its two valence electrons to two Cl atoms and changes into a stable magnesium ion (Mg2+), with a stable octet of electrons in its outer shell.The positively charged magnesium ion (Mg2+) and negatively charged chloride ions (Cl-) are now held together by the electrostatic force of attraction. Dot and cross: Page 26 Q23 Desribe the formation of CaO from its elements. Ans The atomic number of Ca and O are 20 and 18 respectively. So, , their electronic configuration are 2,8,8,2 and 2,6, respectively, so that ,Ca atom has two valence electrons whereas the O atom has 6.When the atoms combine , the two valence electrons of Ca are transferred to the valence shell of oxygen. So, calcium as well as oxygen atom, achieve a stable octet of electrons and thus attain stable noble gas configuration. Dot and cross: Page 27 Q24 How is molecule of calcium oxide formed? (2002) Ans Same as Q17 CHARACTERISTIC S OF ELECTROVALENT COMPOUNDS Q25 Write three Characteristics of Ionic compound. Ans the three characteristics of ionic compounds are as follows: a. They are crystalline in nature. b. They have high melting and boiling points. c They conduct electricity in molten state and in their aqueous solution. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

4

Ionic compounds have high melting and boiling points. Give reason why? Or, why do ionic compounds possess considerably high melting and boiling points? Ans This is due to the strong electrostatic force of attraction between the oppositely charged ions. As a result of this, large amount of energy is needed to break the bond and hence melting and boiling points are high. Q27 Ionic compounds are good conductors of electricity in fused state or aqueous solution.Give reason why Ans Solid ionic compounds do not conduct electricity as the ions are fixed at particular positions and are not free to move. However, when these are melted or dissolved in water, the ions become fee and, therefore, conduct electricity. Q28 Why is sodium soluble in water but not in an organic solvent like benzene? Ans Since sodium chloride (NaCl) is an ionic compound; hence it is soluble in polar solvent like water and insoluble in non polar solvent like benzene. That is why NaCl is soluble in water but not soluble in benzene. Q29 Draw the crystalline structure of NaCl and label the ions. 2014 2 mark Page

Q26

COVALENT COMPOUNDS Q30 What is the limitation of ionic bond? Ans The formation of ionic bond cannot explain the chemical combination between identical atoms or atoms of similar chemical nature to form molecules. Thus it cannot account for the formation of molecules like H2,O2,Cl2,Co2 and also for the organic molecules like methane etc. Q31 What is covalent bond? Ans The bond formed by mutual sharing of electrons between the combining atoms is called covalent bond. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

Ans:

Q33 Ans

Q34 Ans Q35 Ans Q36 Ans

Q37

5

How is a covalent bond formed ? Why are the covalent compounds non-conducting and low melting /boiling point ? 3 marks (2013) Covalent bond is formed by the mutual sharing of electrons between the combining atoms. The covalent compounds are non-conducting because they are made up of neutral molecule. The covalent compounds have low melting and boiling point because the force between the molecules is weak; a comparatively small amount of heat energy is required to overcome these forces. What are covalent compounds? The type of combination between atoms which results from the mutual sharing of pair of electrons between the combining atoms is called covalent bond and the compounds formed are called covalent compounds. What is covalency? The number of electrons contributed by an atom for sharing in the formation of a covalent molecule is known as covalency. What are the different types of covalent bond? The different types of covalent bond are single bond, double bond and triple bond. Explain the formation of Chlorine molecule (Cl2) from two atoms of Chlorine. The electronic configuration of Chlorine atom 3, 8, 7.The two combining atoms of chlorine gives one of its electrons to be shared between them and constitute a shared pair of electons.The two shared electrons are counted for both the atoms .Thus, each Cl atom in a chlorine molecule (Cl2) acquires a stable configuration. Page

Q32

Give the electron dot representation of molecule.What covalency of chlorine in HCl. (2012)

chlorine

Ans: The covalency of chlorine in HCl is one. Q 38 Ans

Explain the formation of hydrogen Chloride molecule .Draw the electronic structure. Hydrogen atom has only one electron and chlorine atom has seven electrons in its valence shell. Hence by mutual sharing of electron pair between them both the atoms acquire nearest noble gas configuration.

Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

6

CHEMICAL BONDING Page

Q39 Explain why Methane ( CH4) Molecule has four pairs of shared electron? Ans In a molecule of methane, the carbon atom and each of the four H atoms acquire the stable configurations of the neon and helium respectively. In methane, we have four carbon-hydrogen (C-H) single bonds. Thus, methane has four pairs of shared electrons. Dot and cross: Page 30 H2 Q40 Explain how water O molecule. Ans

A molecule of water is made up of one oxygen atom and two hydrogen atoms. An oxygen atom is two electrons short and hydrogen atoms are one electron short of a noble gas structure. Thus one atom of oxygen shares two of its electrons with two hydrogen atoms thus attaining a stable configuration. Dot and cross: Page 31 Q41 Describe the formation of ammonia (NH3) molecule. A ns A molecule of ammonia is formed by the combination of one atom of nitrogen with three atoms of hydrogen .Therefore five electrons in the valence shell of nitrogen atom. So, it has three electrons short of to complete its octet and to be stable .When it shares three of its electrons with three H atoms, the stable electronic configuration of neon is achieved. The three H atoms acquire the stable configuration of helium Dot and cross: Page 31 Q42 How many lone pairs and bonding pairs are represent in NH3 molecule. Ans One lone pair and three bonding pairs are present in NH3 molecule. Q43 Covalent compound are generally insoluble in water, but ammonia is soluble in water, Give reasons. Ans Ammonia NH3 readily dissolves in water H 2O because it reacts with water to ions. MULTIPLE COVALENT BONDING Q44 What is a bonding pair of electrons or bond pair? Ans The pair of electrons which take part in bonding are called bonding pair of electrons. Q45 What are lone pairs? Ans The pair of electrons which do not take part in bonding are called lone pairs. Q46 What is single covalent bond? Ans If the two atoms share one electrons pair, the bond is known as single covalent bond and is represented by one dash ( ). Q47 What is double covalent bond? Ans if the two atoms share two electron pairs ,bond is known as double covalent bond and is represent by two dashes ( ). Q48 What is triple bond? Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

Q49 Ans

Q50 Ans

Q51 Ans

Q52 Ans

7

if the two atoms share three electron pairs ,bond is known as triple covalent bond and is represent by two dashes ( ). What do you mean by lone pairs of electrons? How many lone pairs and bonding pairs are present in H 2O ,NH3 and CH4 molecules. Pairs of electrons which do not take part in bonding are called lone pairs. In H2O molecule, there are two lone pairs and two bonding pairs . In NH3 molecules , there are three bonding pairs and one lone pairs. In CH4 molecules, there are only four bonding pairs and no lone pair. Write the configuration of a water molecule and thereafter, mention the number of lone pairs it possesses. In the electronic configuration, the central atom is surrounded by four electron pairs – two of which are bonding pairs and two of which are lone pairs. The number of lone pairs is two. Explain the formation of double bond in Oxygen atom. Two oxygen atoms combine to form an oxygen molecule (O 2) by sharing two electron pairs. Each oxygen atom has six electrons in the valence shell and requires two electrons to complete the octet. Therefore, in the formation of oxygen molecule, both the atoms contribute two electrons each for sharing resulting in two electrons pairs. Hence there is double bond between the two oxygen atoms. Using dot(.) and Cross(x) to represent valence electrons ,explain the formation of carbon dioxide ( CO2 ) molecule. A molecule of carbon dioxide ( CO 2 ) is formed when an atom of carbon combines with two atoms of oxygen. The C atom has dour electrons in its valence shell and thus requires four more electrons to complete its octet while oxygen atom requires two electrons to complete its octet. This is achieved when the carbon atom shares its four electrons with two oxygen atoms to form a carbon dioxide ( CO 2 ) molecule. Dot and cross: Page 32 Page

Ans

Q53 Explain the formation of Nitrogen molecule (N2). Ans In the formation of nitrogen molecule, each of the two nitrogen atoms having five valence electrons provides three electrons pairs for sharing. Thus a triple bond is formed between the two atoms. Dot and cross: Page 32 COORDINATE OR DATIVE BOND Q54 What are Coordinate covalent bonds? Why is it called dative or semi polar bond ? Ans A coordinate covalent bonds or dative bond is a covalent bond in which both the electrons of the shared pair came originally from one atom and none from the other. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

Q55 Ans Q56 Ans Q57 Ans

Q58 Ans

Q59

Page

8

Since co-ordinate bond has some polar character ,it is also called as dative or semi polar bond. What is a DONOR ? The atom which contributes the electrons pair is called the DONOR What is a ACCEPTOR ? The atom which only shares the electron pair is known the ACCEPTOR Explain the formation of ozone (O3) molecule? In O2 molecule, each oxygen atom has two pairs of unused valence electrons. If an atom of oxygen having six valence electrons comes close to O2 molecule, the new atom may share a lone pair of electrons of one of the oxygen atoms of O2 molecule. It gives rise to the formation of a coordinate covalent bond. Dot and cross: Page 33 Describe the formation of hydronium ion (H3O+) . Draw the electronic structure. Water , H2O has lone pair of electron s on oxygen atom while hydrogen ion (H+) has empty K- shell thereby can accommodate two electrons. Thus, oxygen in H2O can easily provide two electrons while H+ ion can accept these electrons to form a coordinate bond between them. Dot and cross: Page 34 NH ¿ Draw the electronic structure of ammonium ion +¿ . ¿ ¿

Ans Dot and cross: Page 34 CHARACTERISTICS OF COVALENT BOND Q60 Why do covalent compounds exist as liquids or gases at room temperature? Ans The covalent compounds do not exist as ions but they exist as molecules. There are weak inter molecular forces between the molecules. Hence they usually exist as liquids or gases at room temperature. Q61 Give reason why covalent compounds generally have low melting and boiling points? Ans Since the forces between the molecules are weak, a comparatively small amount of heat energy is required to overcome these forces. Hence covalent compounds generally have low melting and boiling points. Q62 Covalent compound cannot conduct electricity. Give reason, why? Ans Because they are made up of neutral molecules, not ions. Q63 Write three properties of covalent compound. Ans Three properties of covalent compound are as follows: a. They have low melting and boiling points Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING Page

9

b. They are soluble in polar solvents like water but insoluble in polar solvents like benzene. c. They do not conduct electricity. Q64 Why is a hydrogen atom molecule generally diatomic and not mono-atomic? Ans Hydrogen atom cannot exist as mono-atomic because H-atom has one electron in its outermost shell, so it is unstable and possess high energy. One hydrogen atom can combine with another hydrogen atom by sharing an electron pair and duplet is achieved. Hence, hydrogen molecules are diatomic. DO COVALENT BONDS SHOWS IONIC CHARACTER ? Q65 Defined the term the electro negativity of the atom. Ans The relative tendency of an atom to attract electrons to itself when combined in a compound is called the electro negativity of the atom. Q66 Give two conditions under which polar covalent bonds formed. (2000) Ans: Conditions form polar covalent bonds are as follows: (i) Atoms should be different (ii) The bond pairs should be shared unequally to atoms. Q67 Why do shared pair of electrons in H2 molecule is situated in between the identical nuclei? Ans Because the shared pair of electrons is equally attracted by the two atoms. Q68 If the atoms forming bonds are different, the electron attracting tendency of the two atoms may differ. Explain why? Ans As a result of the difference in electro negativity, the shared electron pair will be displaced towards the atom with more electron attracting tendency or electro negativity. Q69 Why does the molecule HCl have a dipolar character? (2000) Ans Same as Q70 Q70 Why does the molecule HCl have a dipolar character? Ans Because the shared electron pair will be more attracted towards the chlorine end of the molecule. So the chlorine end of the molecule will be slightly negative and the hydrogen end slightly positive. Thus, the HCl have a dipolar character. Q71 What are polar covalent compounds? Give a condition under which such bonds are formed. Ans All covalent bonds between unlike atoms are partially polar. The shared electron pair will be displaced towards the atom with more electron attracting tendency or electro negativity. Thus, they are called polar covalent compounds. Condition: A polar covalent bond is formed between different atoms. Q72 What do you mean by partially polar? Ans Those molecules which develop a partial ionic character even though it is a covalent molecule are said to be partially polar. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

10

Ans

Explain why HF is considered to be a polar covalent compounds. (2015) 1 mark Fluorine (F) has more electro negativity that of Hydrogen (H) .The shared electron pair would be attracted more towards the Fluorine end of the molecule. So the Chlorine end of the molecule will be slightly negative and the hydrogen end slightly positive, these are −¿ +¿∧δ ¿ represented as charges. δ¿ Page

Q73

δ−¿ +¿ ¿ δ −H H¿ Q74 Why is water a polar covalent compound? Ans Water is a polar covalent compound because the shared electron pair is unequally attracted by hydrogen and oxygen atom i.e. the shared electron pair is more attracted towards the oxygen atom developing −¿ +¿∧δ ¿ charges . δ¿ Diagram : page 35 Q75 Why is water molecule V- shaped? Ans The water(H2O) molecule contains two covalent bonds between the oxygen and hydrogen atoms. These two bonds are not symmetrically arranged, and H2O molecule is V-shaped. Q76 Why is water a polar solvent? Ans The water (H2O) molecule contains two covalent bonds between the oxygen and hydrogen atoms. These two bonds are not symmetrically arranged, and H2O molecule is V-shaped. This result in the polar character of water .Hence water is a polar solvent. Q. What is the type of bonding in water? Write down the electronic structure of it Why is water molecule polar? Ans: Try yourself BONDING IN METAL Q77 What is Metallic bonding? Ans The simultaneously force of attraction between the positively charged kernel and the mobile electrons which binds the metal atoms together is called metallic bonding. Q78 Who proposed the electron sea model? Ans Lorentz Q79 Define electron sea model? Ans According to model, a metal lattice consist of positively charged kernels arranged in a regular way surrounded by loosely held valence electrons. Q80 What are kernels? Why is it called electron sea model? Ans Kernels are metal nuclei and other electrons except valence electrons. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

Page

11

It is called electron sea model there is a sea of valence electrons in which positively charged kernels are immersed. Q81 Draw a neat diagram of electron sea model of metallic bonding and label the kernels and valence electron. 2 marks 2013 .Ans For Diagram see on page 36 TEXTUAL QUESTIONS (page 28) Ans1 Electronic configuration having eight electrons in their outermost shells (two in case of there is K-shell) favours inert or noble behavior of element. Ans2 The outermost shells of the atoms of all elements other than noble gases do not have stable configurations. Therefore, they combine with each other or with other atoms to acquire stable nearest noble gas electronic configurations. Thus, Most of the elements form atom. Ans3 Electropositive elements can form cations. E.g: (i) Na Na+ + e2,8,1 2,8 (ii) Ca Ca2++2e2,8,8,2 2,8,8 Ans4 Electronegative elements can form anions. E.g (i) Cl + eCl2,8,7 2,8,8 (ii) O+e2O22,6 2,8 Ans5 The electronic configuration of Sodium atom is 2,8,1, so the atom can lose one electron from its outermost shell to attain the nearest inert gas configuration. Whereas, the electronic configuration of sodium ion is 2, 8 and get its octet. Thus sodium atom reacts vigorously with water, but sodium ion does not. Ans6 The type of combination between atoms which depend upon the transfer of electrons and in which oppositely charge ions are held together by electrostatic force of attraction is called electrovalent or ionic bond. The three conditions for its formation (i) When electropositive element can lose one or more valence electron to attain nearest inert gas configuration. (ii) When electronegative element can accept one or more valence electrons to attain nearest inert gas configuration. (iii) When the electrostatic force of attraction develop between the oppositely charged ion i. e cations and anions. PAGE 36 Ans 2 Since carbon tetrachloride is a neutral molecules, there is no free electron to move. Hence, it cannot conduct electricity. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

CHEMICAL BONDING

12

A normal covalent bond is formed by mutual sharing of electron pair between the atoms of two similar or dissimilar elements to attain the stable configuration of the nearest inert gas configuration. Whereas, in co-ordinate bond an electron pair bond is formed in which both the electrons of the shared pair came originally from one atom and none from the other. Ans4 In the formation of hydrogen molecule, H2, the two hydrogen atoms approach each other, the single electron of both the atoms forma shared pair. This electron pair revolves around the two nuclei of Hatoms and it is contained in the electron shells of both the atoms and each hydrogen atom attains the electronic configuration of the nearest inert gas helium. Thus, H2 exist. Whereas, Helium (He) has two electrons in the k- shell to get its duplet and become stable. Thus ,He2 does not exist. Page

Ans3

Ans5 The shared electron pair would be attracted more towards the Fluorine end of the molecule. So the Chlorine end of the molecule will be slightly negative and the hydrogen end slightly positive, these are −¿ +¿∧δ ¿ represented as charges. δ¿ δ−¿ δ +¿ −H ¿ H¿ Thus, HF is polar. While H2 and F2 molecules, the shared pair of electrons is equally attracted by the two atoms. That is why they are not polar. PAGE -37 Ans1 The outermost shell of an atom of an element is called Valence shell. The number of electrons present in the outermost shell of the atom is called valence electrons. Ans2 Elements combine chemically because the element other than noble gases have less than eight electron in their outermost shells .So, these element combine with each other or with other atoms to decrease there energy to a minimum level and acquire stable nearest noble gas configuration . Ans3 Ionic bond Covalent bond (i) This is formed due to the strong (i) This is formed due to the weak electrostatic force of intermolecular forces between attraction. the molecules. (ii) These are formed when an This is formed by mutual sharing electropositive element of electrons between the combines with electropositive combining atoms. element. Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed

GSCIENCE CLASSES

Example from text book.

13

CHEMICAL BONDING

Page

IMPORTANT PREVIOUS YEARS QUESTIONS (5 Marks ) Q 1 Explain how an electrovalent bond is formed. What type of chemical bond is present in sodium oxide ? Show the type of bond formed by using dot(.) and Cross(X) to represent electrons of different atoms. 3+1+1=5 (1995) Q2 What is an electrovalent compound Give two properties of an electrovalent compound.Using ‘ dot (.) ’and ‘cross (x) to represent electronic different atoms, write the formation sodium chloride molecules. Q3 How is an ionic bond formed Write any three characteristics properties of ionic compound. Using dot(.) and cross(X) to represent electrons of different atoms draw the electronic structure of calcium oxide. 1+3+1=5 1996 Q4 What are the types of bonding in water and calcium oxide Write down the electronic structure of water and calcium oxide. Why is water molecule V shape? Q5 How is covalent bond formed? Using dot(.) and Cross(x) to represent electrons, describe the formation of the bond that holds two oxygen atoms together in an oxygen molecule. State two characteristics properties of covalent compound. 1+2+2=5 . Q6 An element X(atomic no. 15) combines with another element Y( atomic no. 1) .What will be the nature of the bond formed? Using dot(.) and cross(x) to denote valence electrons give the electronic structure of the compound and suggest any two properties of the compound .1+1+1+2=5 Q7 Two elements A and B have the atomic number 15 and 17 respectively. What type of bonding will be formed when A and B combine and what will be the formula of the compound ? 1+1+3=4

Prepared by Tutor :Ph Gokul Sharma (8974434474) M.Sc(Physics )

B.Ed

Not to be distributed