WAJA F4 Chemistry 2009 Chapter 5: Chemical Bonds

CHAPTER 5 : CHEMICAL BONDS

A Formation of Compounds

Learning Outcomes:

You should be able:

  • explain the stability of noble gases
  • explain the conditions for the formation of chemical bonds
  • state the types of chemical bonds

Activity 1: Formation of chemical bonds

Choose the correct answer from the table

1 / Noble gases are ………………… gases. They exist as……………………….. gases and
are chemically unreactive. They have ………….………….. octet or ……………..……… electron …………………………..
2 / Other atoms besides noble gases tend to achieve the stable electron arrangement through the formation of …………………………
3 / Two types of chemical bonds :
(i) / …………………….. bond
- formed when atoms join together by transferring of electrons
(ii) / …………………….. bond
- formed when atoms join together by ………………………………..of electrons

B IONIC BONDS

Learning outcomes:

You should be able to:

  • explain the formation of ions
  • write the electron arrangements for the ions formed
  • explain the formation of ionic bonds
  • illustrate electron arrangement of an ionic bond
  • illustrate the formation of ionic bonds

Activity 2 : Formation of ions

1 / Underline the correct answer.
To achieve astable electron arrangement:
(i) / A metal atom(donates/accepts) electrons , forming a (positive/negative) ion
called cation .
(ii) / A (non-metal/ metal)atom accepts electrons , forminga (positive/negative) ion
called anion .
2 / Complete the diagram below.
(a) /
(b) /

(Refer to page 84 – 85 - F4 Chemistry text book)

Activity 3 : Formation of ionic bonds

Fill in the blanks with the correct words.

1 / Formation of ionic compound, sodium chloride ()
  • Electron arrangement of sodium atom is ......
  • A sodium atom ………………….one electron to achieve the ………………electron arrangement which is 2.8.
  • Sodium ion, ……..…...... is formed
  • Electron arrangement of chlorine atom is…………………………………………..
  • Electron from sodium atom is transferred to a …………………………….…atom
  • A chlorine atom …………………………electron from sodium atom to ………………………….. thestable electron………………………which is 2.8.8
  • Chloride ion,………………….. is formed
  • The sodium ion, and chloride ion, formed are ……………………..to one another to form an ionic compound …………………….., .
  • The strong ……………………………….forces between the opposite-charged ions is called ………………………….bond.
(Refer to page 86 -F4 Chemistry text book)
2 / Complete the diagram below.
2.8.1 2.8.7 ......
Sodium atom,Na Chlorine atom,Cl Sodium ion, …… Chloride ion, …..
3
(a) / Fill in the blanks with the correct answers.
Formation of ionic compound magnesium chloride, MgCl2 .
  • Electron arrangement of magnesium atom is ......
  • A magnesium atom ………………….two electrons to achieve the ………………electron arrangement which is, 2.8.
  • Magnesium ion, ……..…...... is formed
  • Electron arrangement of chlorine atom is…………………………………………
  • Electrons from magnesium atom is transferred to two ………………….…atoms
  • A chlorine atom …………………………electron from magnesium atom to …………….. thestable electron …………………………which is 2.8.8.
  • Chloride ion,………………….. is formed
  • The magnesium ion,Mg2+and two chloride ions,formed are ………………to one another to form an ionic compound …………………………., MgCl2
  • The strong ……………………………….forces between the opposite-charged ions is called …………………………..bond
(Refer to page 86 -F4 Chemistry text book)
(b) / Complete the diagram below.

(Refer to page 86 -F4 Chemistry text book)

C Covalent Bonds

Learning Outcomes:

You should be able :

  • state the meaning of covalent bonds
  • explain the formation of covalent bonds
  • illustrate the formation of covalent bonds
  • compare and contrast the formation of ionic and covalent bonds

Activity 4: Formation of covalent bonds

Fill in the blanks with the correct words.

1 / Covalent bonds are formed when..………………… atoms …………………….. electrons to achieve …………………….electron arrangements.
2 / Types of covalent bonds:-
(i) / …………………………………………………………………………………………………
(ii) / …………………………………………………………………………………………………
(iii) / …………………………………………………………………………………………………
3 / A single bond is formed when …………………of electrons is shared between two atoms.
A double bond is formed when ………………..of electrons is shared between two atoms.
A triple bond is formed when ………………….of electrons is shared between two atoms.
4 / Formation of hydrogen molecules, H2 :-
  • A hydrogen atom has ……valence electron, with an electron arrangement of..…….
  • It needs ……….. more electron to achieve the ……………..electron arrangement
  • ………..hydrogen atoms ………………… one electron each for ………………
  • Shared-paired electrons forms a …………….. bond in the hydrogen molecule, H2
  • Single bond holds the two hydrogen atoms together because the shared-pair of electrons is attracted to the………………….. of both atoms

5 / Complete the diagram below.
(a) /
(b) / A covalent bond can be illustrated by using……………………………….

Activity 5: Formation of covalent bonds

1 / Formation of oxygen molecules, O2 :
  • An oxygenatom has …… valence electron, with an electron arrangement of…..…
  • It needs ……….more electrons to achieve the …………….. electron arrangement
  • …....oxygen atoms share………pairs of electrons forminga…..……………bond

2
(a) / Draw the electron arrangement for the formation of oxygen molecule.
[Proton number : O, 8 ;]
(b) / Illustrate the formation of oxygen molecule using the Lewis structure.
3 / Formation of a nitrogen molecule, N2 :
  • A nitrogen atom has …… valence electron, with an electron arrangement ..……..
  • It needs ……… more electrons to achieve the …………….. electron arrangement
  • ………..nitrogen atoms share………………pairs of electrons forminga ……………… covalent bond

4 / Draw the electron arrangement for the formation of nitrogen molecule.
[Proton number : N, 7]
(b) / Illustrate the formation for nitrogen molecule using the Lewis structure.

Activity 6

1 / Draw the electron arrangements for the formation of the following ionic compounds:
[Proton number : Li, 3 ; Ca, 20 ; O, 8 ; Cl, 17 ]
(a) / Lithium oxide,
(b) / Calcium chloride,
2 / Draw the electron arrangements for the formation of the following covalent compounds
[Proton number : C, 6 ; Cl, 17, : O, 8]
(a) / Tetrachloromethane, CCl4
(b) / Carbon dioxide molecule, CO2
3 / Complete the table belowto compare the characteristics for the formation of ionic and covalent bonds.
Ionic bond / Characteristic / Covalent bond
Valence electrons / Electrons involved
Elements / Non-metals atom and non metal atoms
Electron transfer to achieve stable electron arrangement / Bond formation
Particles

D PROPERTIES OF IONIC AND COVALENT BONDING

Learning outcomes

You should be able to:

  • list the properties of ionic compounds.
  • list the properties of covalent compounds
  • explain the differences in the electrical conductivity of ionic and covalent compounds
  • describe the differences in melting and boiling points of ionic and covalent compounds
  • compare and contrast the solubility of ionic and covalent compounds
  • state the uses of covalent compounds as solvents.

Activity 7 : Physical properties of ionic and covalent compounds

1. Complete the table of the properties of ionic and covalent compounds, using the words

given in the box :

Ionic compound / Properties / Covalent compound
Physical states at room temperature
Melting points
Boiling points
Electrical Conductivity
Solubility in water
Solubility in organic solvent
2 / Explain why ionic compounds are able to conduct electricity in aqueous solution or in molten state but not in solid state.
……………………………………………………………………………………………………….
……………………………………………………………………………………………………….
……………………………………………………………………………………………………….
3 / Explain why covalent compound do not conduct electricity in all states.
……………………………………………………………………………………………………….
……………………………………………………………………………………………………….
4 / Explain why ionic compounds have higher melting points than covalent compounds.
……………………………………………………………………………………………………….
……………………………………………………………………………………………………….
………………………………………………………………………………………………………
5 / Example of covalent compounds ;-......
Uses of covalent compounds as solvent in our daily lives: ………......
………………………………………………………………………………………………………

(Refer to page 90 - 91 -F4 Chemistry text book)

Activity 8

1 / /
Atom A Atom B
(a) / Write the electron arrangement for atom A.
………………………………………………………………………………………………..
(b) / A and B can form a compound
(i) / What type of bond holds atom A and B together?
…………………………………………………………………………………………..
(ii) / What will happen to atom A during the formation of the compound with atom B?
…………………………………………………………………………………………..
(iii) / Draw the electron arrangement of the compound formed in (b)(ii).
(iv) / State one physical property of the compound formed.
…………………………………………………………………………………………..
(c) / Carbon atom, C, with an electron arrangement of 2.4 can combine with atom B to form a compound.
(i) / What is the molecular formula of the compound formed?
………………………………………………………………………………………….
(ii) / If the relative atomic masses of carbon is 12 and B is 32, what is the relative molecular mass of the compound in c(i).
…………………………………………………………………………………………..

Activity 9

1 / The diagram below shows the proton number and the nucleon number for three atoms of elements, E , G and W. The letters used do not represent the actual symbols of the elements.
(a) / The reaction between atoms of element G and W forms an ionic compound whereas the reaction between atoms of element E and W forms a covalent compound.
Explain how these ionic and covalent compounds are formed.
Ionic compound
  • Electron arrangement of an atom of element G is ......
  • AtomG ………………….one electron to achieve the ………………electron arrangement which is 2.8
  • G ion, ……..…...... is formed
  • Electron arrangement of atom W is…………………………………………..
  • Electron from atom G is transferred to an atom of…………………
  • Atom W receives ………….electron from atom G to achieve the ……….……………. electron arrangement which is 2.8.8
  • W ion,………………….. is formed
  • The G ion, ……….. and W ion, ………..formed are …………………………..to one another to form an …….………compound, ……….
  • The strong ……………………………….forces between the opposite-charged ions is called ………………………….. bond.

Covalent bond
  • Atom E has ……...valence electrons, with an electron arrangement of..……...
  • It needs ……….. more electrons to achieve the ……………..electron arrangement
  • One atomof Econtributes four electrons for ………………
  • Atom W has ………valence electrons, with an electron arrangement of…………….
  • It needs ………….more electron to achieve the……………….electron arrangement
  • One atom of E share a pair of electrons with ………….atoms of W
  • Covalent compound of ………………is formed

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