5.2Ionic Bond
An ionic bond is a chemical bond formed through the transfer of electrons between a metal atom and a non-metal atom. Metal atoms donate valence electrons to form positively-charged cations, while non-metal atoms accept electrons to form negatively-charged anions. The resulting oppositely charged ions are held together by strong electrostatic attraction forces known as ionic bonds.
Learning Objectives
- Explain the meaning and formation of an ionic bond.
- Explain the formation of positive ions (cations) from metal atoms and negative ions (anions) from non-metal atoms.
- Write half-equations for the formation of cations and anions.
- Describe the formation of ionic compounds, such as sodium fluoride (\(\text{NaF}\)), using electron arrangement diagrams and electrostatic attraction forces.
Formation of Sodium Fluoride, \(\text{NaF}\)
Electron transfer from a sodium atom to a fluorine atom forms oppositely charged ions held by electrostatic attraction forces.
Brief Explanation
Understand how atoms achieve stable octet electron arrangements through electron transfer.
1. Formation of Cations
A metal atom donates valence electrons to achieve a stable octet or duplet electron arrangement.
Example: Sodium atom, \(\text{Na}\), has electron arrangement 2.8.1. It donates 1 valence electron to form \(\text{Na}^+\), with electron arrangement 2.8.
Half-equation: \(\text{Na} \rightarrow \text{Na}^+ + \text{e}^-\)
2. Formation of Anions
A non-metal atom receives electrons from a metal atom to achieve a stable octet electron arrangement.
Example: Fluorine atom, \(\text{F}\), has electron arrangement 2.7. It accepts 1 electron to form \(\text{F}^-\), with electron arrangement 2.8.
Half-equation: \(\text{F} + \text{e}^- \rightarrow \text{F}^-\)
| Particle | Electron arrangement | Protons | Electrons | Net charge |
|---|---|---|---|---|
| Sodium ion, \(\text{Na}^+\) | 2.8 | 11 | 10 | +1 |
| Fluoride ion, \(\text{F}^-\) | 2.8 | 9 | 10 | −1 |
Try These Questions First
Answer mentally, then check the explanation.
What type of chemical bond is formed between a metal atom and a non-metal atom?
Write the half-equation for the formation of a sodium ion from a sodium atom.
Why does a fluorine atom accept an electron instead of donating its valence electrons?
Common Mistakes
Avoid these errors when writing ionic equations and drawing ion diagrams.
Common Misconceptions
Compare each misconception with the correct fact.
Both atoms must have the same number of valence electrons before bonding.
Metal atoms have few valence electrons (typically 1, 2, or 3) which they donate, while non-metal atoms have more valence electrons (typically 5, 6, or 7) which accept electrons to reach 8.
An ionic bond is a physical stick or link connecting two atoms.
An ionic bond is an invisible, strong electrostatic force of attraction between oppositely charged ions.
Summary
Key facts to remember.
- An ionic bond forms through the complete transfer of electrons from a metal atom to a non-metal atom.
- Metal atoms donate electrons to form cations with positive charges.
- Non-metal atoms receive electrons to form anions with negative charges.
- The electrostatic attraction force between oppositely charged cations and anions constitutes the ionic bond.
Quick Activity
Complete all parts before checking your score.
A. Objective Quiz
Which of the following occurs when a sodium atom forms a sodium ion?
What holds the sodium ion (\(\text{Na}^+\)) and fluoride ion (\(\text{F}^-\)) together in sodium fluoride?
B. Fill in the Blanks
A metal atom donates valence electrons to form a positively-charged ion called a ______.
Fluorine atom with electron arrangement 2.7 accepts one electron to form a fluoride ion with an electron arrangement of ______.
C. Match the Particle or Concept with Its Description
Drag each item on desktop. On mobile, tap an item and then tap the matching box.
Answer Choices
Sodium atom (\(\text{Na}\)) Fluoride ion (\(\text{F}^-\)) \(\text{Na} \rightarrow \text{Na}^+ + \text{e}^-\) Ionic bondDescription / Representation
Keywords
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