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Introduction to Chemistry and Laboratory Apparatus | Week 15 Topics1 Quiz
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Nature of Matter | Week 23 Topics1 Quiz
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Separation Techniques I | Week 31 Topic
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Separation Techniques II | Week 45 Topics1 Quiz
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Particulate Nature of Matter I | Week 55 Topics1 Quiz
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Particulate Nature of Matter II | Week 69 Topics1 Quiz
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Symbols, Formulae & Oxidation Number | Week 77 Topics1 Quiz
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Laws of Chemical Combination | Week 84 Topics1 Quiz
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Chemical Equation & Chemical Combination (Chemical Bonding) I | Week 94 Topics1 Quiz
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Chemical Combination (Chemical Bonding) II | Week 104 Topics1 Quiz
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Chemical Combination (Chemical Bonding) III & Shapes of Covalent Molecules | Week 113 Topics1 Quiz
Topic Content:
- Meaning of Electrovalent Bonding
- Formation of Sodium Chloride (Na+Cl–)
- Structure of Sodium Chloride
- Formation of Magnesium Oxide (Mg2+O2-)
- Formation of Calcium Fluoride (Ca2+2F–)
- Characteristic Properties of Electrovalent (Ionic) Compounds
The main principle of this type of bonding is donor/acceptor principle.
Electrovalent bonding is the complete transfer of electrons from the outermost shell of a metal to the outer-most shell of a non-metal.
The metals donate electrons while non-metals accept electrons. After combination, both the metal and non-metal will form a stable structure i.e. attain the octet or duplet structure of rare gases.
The metals are positively charged, while the non-metals are negatively charged.
Example:
Formation of Sodium chloride (Na+Cl–):
Equation for the Reaction:
\( \scriptsize Na \: \rightarrow \: Na^+ \:- \: e^- \) ………….(i)
\( \scriptsize Cl \: \rightarrow \: Cl^- \: + \: e^- \) ………….(ii)
Add equation (i) and (ii) together
The e– cancel out
\( \scriptsize Na \: + Cl \: \rightarrow \; Na^+ Cl^- \)
Diagrammatic Representation:
Structure of Sodium Chloride:
Sodium chloride exists as face-central cubic crystals composed of cationsCations are positively charged ions (atoms or groups of atoms that have more protons than electrons due to having lost one or more electrons). Cations are attracted to negatively charged electrodes... More Na+ and anions Cl– arranged as shown in the figure below.
A close look at the figure shows that the number of anions (Cl–) surrounding a cation (Na+) is six, and also the number of cations surrounding a single anion is six i.e. the coordination number of each of Na+ or Cl– is six. Hence, the opposite ions exist in a simple ratio of 6:6 or 1:1.
Formation of Magnesium Oxide (Mg2+O2-):
Equation for the Reaction
\( \scriptsize Mg \: \rightarrow \: Mg^{2+} \: – \: 2e^- \) ………….(i)
\( \scriptsize O \: \rightarrow \; O^{2-} \: + \: 2e^- \) ………….(ii)
Add equation (i) to (ii)
2e– cancels out
\( \scriptsize Mg \: + \: O \; \rightarrow \: Mg^{2+} O^{2-} \)
Diagrammatic Representation:
Formation of Calcium Fluoride (Ca2+2F–):
Equation for the Reaction
Ca \( \scriptsize \rightarrow \) Ca2+ – 2e– ………… equation (i)
F2 \( \scriptsize \rightarrow \) F2– + 2e– ………… equation (ii)
Add equation (i) to (ii)
2e– cancels out
Ca + F2 \( \scriptsize \rightarrow \) Ca2+ + F2–
Diagrammatic Representation:
Characteristic Properties of Electrovalent (Ionic) Compounds:
1. Electrovalent compoundsAn electrovalent or ionic bond is formed when a metal atom transfers one or more electrons to a non-metal atom. Ionic or electrovalent compounds are those compounds which are formed by... More exist as an aggregate of positively charged ions, which are held together by strong electrostatic forces
2. They have high melting and boiling points due to strong electrostatic forces which hold the ions together.
3. They are soluble in water or polar solvent but insoluble in a non-polar solvent like – benzene, ether, etc.
4. They are electrolytes or they conduct electricity in solution or molten form.
5. They are solids that do not vaporise easily.
