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IGCSE Notes Ions and ionic bonds

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IGCSE Chemistry Revision Notes

Topic:Atoms, elements and compounds

Sub Topic: 2.4 Ions and ionic bond

Syllabus Objectives

Core :

  • Describe the formation of positive ions, known as cations, and negative ions, known as anions
  • State that an ionic bond is a strong electrostatic attraction between oppositely charged ions
  • Describe the formation of ionic bonds between elements from Group I and Group VII, including the use of dot-and-cross diagrams
  • Describe the properties of ionic compounds:
  1. high melting points and boiling points
  2. good electrical conductivity when aqueous or molten and poor when solid

EXTENDED/SUPPLEMENT

  • Describe the giant lattice structure of ionic compounds as a regular arrangement of alternating positive and negative ions
  • Describe the formation of ionic bonds between ions of metallic and non-metallic elements, including the use of dot-and-cross diagrams
  • Explain in terms of structure and bonding the properties of ionic compounds:
  • (a) high melting points and boiling points
  • (b) good electrical conductivity when aqueous or molten and poor when solid

Revision Notes

IGCSE Chemistry  Notes Ions and ionic bonds

IONS AND IONIC BONDS

  1. 1.    Ions are electrically charged particles formed by the loss of gain or electrons.
    2.    Anions(-vely charged) are negatively charged ions formed by gaining electrons.
    3.    Cations are positively charged ions formed by losing electrons.
    4.    The electrostatic attraction between the positive ions and the negative ions results in an ionic bond
    5.    Atoms lose or  gain electrons to attain the stable electronic structure of the nearest inert element and become more stable.
    6.    When elements of group 1 an 7 react, the group 1 atom loses an electron and the group 7 gains it. 

Formation of sodium chloride:

igcse-chemistry-notes-sodium-chloride-ionic-compound-diagram

 

In the formation of sodium chlorine, sodium atom loses one electron and becomes a +vely charged cation. The chlorine atom accepts this electron and forms a negatively charged ion called the anion. Thus by doing so both the ions have a stable electronic structure which is the same as the noble gas. So a stable electronic structure has been formed. 

Formation of calcium chloride:

 

Ionic and covalent-Compounds-A comparison

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  Covalent Ionic
Formed between Non -metals Metals and non-metals
Melting points and boiling points Low melting and boiling points because the intermolecular attractive forces are very weak. Exceptions are: SiO2 with a high melting point High melting and boiling points because of strong electrostatic forces between the ions in the giant lattice
Solubility Insoluble in water ( Exceptions: sugar and amino acids-water soluble) Soluble in water because the water molecules are able to separate the ions from one another and keep them in the solution.
Electrical conductivity Do not conduct electricity because they have no ions. Hydrogen chloride gas, a covalent compound reacts with water to form HCl acid which splits up into ions. They conduct electricity in the molten or aqueous form due to the presence of mobile ions.

Topic: Formation of Ions and Ionic Bonding

Click the highlighted blanks to reveal the correct answer.

1 Formation of Ions

1. An
________________ ion
is an atom or group of atoms that has gained or lost
________________ electrons
.
2. Gaining or losing electrons results in a net electrical
________________ charge
.
3.
________________ cations
are positively charged ions formed when atoms lose electrons.
4.
________________ anions
are negatively charged ions formed when atoms gain electrons.
5. Cations are usually formed by
________________ metal atoms
.
6. Metals have few electrons in their outer shell and tend to
________________ lose them easily
.

2 Sodium and Chlorine Ions

7. A sodium atom has the electronic configuration
________________ 2,8,1
.
8. Sodium loses
________________ 1 electron
to form a Na+ ion.
9. The electronic configuration of Na+ is
________________ 2,8
.
10. Anions are usually formed by
________________ nonmetal atoms
.
11. Nonmetals have nearly full outer shells and tend to
________________ gain electrons
.
12. A chlorine atom has the electronic configuration
________________ 2,8,7
.
13. Chlorine gains
________________ 1 electron
to form a Cl- ion.
14. The electronic configuration of Cl- is
________________ 2,8,8
.

3 Ionic Bonding

15. An ionic bond forms when one atom
________________ loses electrons
and another atom
________________ gains electrons
.
16. Ionic bonding usually occurs between a
________________ metal
and a
________________ non-metal
.
17. Ionic bonding happens through the
________________ transfer of electrons
.
18. The ions formed are held together by a strong
________________ electrostatic force of attraction
.
19. In ionic compounds, the resulting ions have
________________ full outer electron shells
.

4 Properties of Ionic Compounds

20. Ionic compounds have
________________ high
melting and boiling points because of strong electrostatic forces.
21. Ionic compounds are often
________________ soluble
in water.
22. Ionic compounds conduct electricity in the
________________ molten or aqueous
state due to mobile ions.

5 Covalent Compounds

23. Covalent compounds are usually formed between
________________ non-metals
.
24. Covalent compounds usually do
________________ not
conduct electricity because they have no ions.

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IGCSE Chemistry Revised Syllabus Notes[ 2023-2025 exams]

1-States of matter

2 Atoms, elements and compounds

3 Stoichiometry

4 Electrochemistry

5 Chemical energetics

6 Chemical reactions

7 Acids, bases and salts

8 The Periodic Table

9 Metals

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10 Chemistry of the environment

11 Organic chemistry

12 Experimental techniques and chemical analysis