Metals and Non-metals · Lesson 7 of 13
How Do Metals And Non-metals React?
“Metals give away electrons, non-metals accept them, and ionic compounds are born from the attraction.”
• Explain why atoms tend to attain stable outer electron shells. • Show electron transfer in the formation of sodium chloride. • Show electron transfer in the formation of magnesium chloride. • Distinguish cations from anions. • Explain ionic compounds as aggregates of oppositely charged ions held by electrostatic attraction.
Noble gases have completely filled outer shells and show little chemical activity. Other atoms can become more stable by losing or gaining electrons until their outer shell resembles a stable noble-gas arrangement.
How Do Metals And Non-metals React?
Electronic Configuration And Stable Shells
Sodium has configuration 2,8,1 and can lose one outer electron. Chlorine has 2,8,7 and can gain one electron. This makes electron transfer between them favourable.
| Element | Electronic Configuration | Tendency |
|---|---|---|
| Sodium | 2,8,1 | Loses one electron |
| Magnesium | 2,8,2 | Loses two electrons |
| Aluminium | 2,8,3 | Can lose three electrons |
| Oxygen | 2,6 | Gains two electrons |
| Chlorine | 2,8,7 | Gains one electron |
Formation Of Sodium Chloride
A Cation is a positively charged ion formed when an atom loses one or more electrons.
After losing one electron, sodium has more protons than electrons and becomes Na⁺.
An Anion is a negatively charged ion formed when an atom gains one or more electrons.
Chlorine gains the electron and becomes Cl⁻. The opposite charges attract strongly.
An Ionic Compound is formed when oppositely charged ions produced by electron transfer are held together by strong electrostatic forces.
Sodium chloride exists as an aggregate of oppositely charged ions rather than as separate NaCl molecules.
Formation Of Magnesium Chloride
Magnesium has configuration 2,8,2 and loses two electrons to form Mg²⁺. Two chlorine atoms each gain one electron and become two Cl⁻ ions.
Problem
Explain why one Mg²⁺ combines with two Cl⁻ ions.
- 1.Mg loses two electrons and becomes Mg²⁺.
- 2.Each chlorine gains one electron and becomes Cl⁻.
- 3.Two chloride ions give total charge −2.
- 4.One Mg²⁺ and two Cl⁻ balance electrically.
- 5.Therefore the formula is MgCl₂.
Metal And Non-metal Roles
In the examples, the metal loses electrons and forms a positive ion, while the non-metal gains electrons and forms a negative ion. Electrostatic attraction between the ions creates the ionic compound.
Quiz
What ion forms when sodium loses one electron?
Why does chlorine form Cl⁻?
What is a cation?
What holds sodium chloride together?
Why are two chloride ions needed for one Mg²⁺?
Practice Problems
- Write the electronic configurations of sodium and chlorine and show electron transfer.
- Define cation and anion and give one example of each.
- Explain why sodium chloride is described as an ionic compound.
- Show electron transfer in magnesium chloride and explain why the formula is MgCl₂.
- Compare the roles of metals and non-metals in ionic compound formation.
- Using oxygen configuration 2,6, explain why oxygen tends to gain two electrons.
Key Takeaways
• Metals can attain stable outer shells by losing electrons and forming positive ions. • Non-metals can attain stable outer shells by gaining electrons and forming negative ions. • Sodium transfers one electron to chlorine to form Na⁺ and Cl⁻. • Magnesium loses two electrons and is balanced by two chloride ions in MgCl₂. • Ionic compounds are held together by strong electrostatic attraction between opposite ions.