Ionic Bonding | WJEC GCSE Chemistry Revision Notes 2016

Formation of Ions

• Ion: Electrically charged atom/group of atoms from loss/gain of electrons.
• Objective: Achieve a full outer electron shell.
• Electronic Structure: Group 1, 2, 6, 7 ions mimic noble gases (e.g., He, Ne, Ar).
• Anions: Negative ions formed by gaining electrons (more electrons than protons).
• Cations: Positive ions formed by losing electrons (more protons than electrons).
• Metals: Lose electrons, become positively charged.
• Non-metals: Gain electrons, become negatively charged.

Diagrams

• Sodium Ion Formation: Sodium atom loses its outer shell electron, forming a positive ion.
• Chloride Ion Formation: Chlorine atom gains an electron, forming a chloride ion.

Electrostatic Forces

• Ionic compounds held by strong electrostatic attraction between oppositely charged ions.

Dot & Cross Diagrams

• Purpose: Show electron arrangement in ionic compounds.
• Notation: Dots and crosses represent electrons.
• Ion Charge: Indicated using brackets and charges at the top right corner.

Example

• Sodium Chloride: Sodium transfers an electron to chlorine, illustrated with dot and cross diagram.

Examiner Tips

• The number of electrons gained/lost equals the charge (e.g., magnesium loses 2 electrons = 2+ charge).
• Use clear dot and cross notation to show electron transfer.

Conclusion

• Ionic bonding involves the transfer of electrons to achieve full outer shells, forming ions.
• Strong electrostatic forces between ions maintain the structure of ionic compounds.

For further practice, students can refer to the Save My Exams website for additional resources and past papers.