# Ionic and covalent bonds

> Give electrons or share them


## Objectives

- Describe the ionic bond: transfer of electrons, then attraction between oppositely charged ions.
- Describe the covalent bond: sharing of electron pairs between atoms.
- Decide which bond forms in a simple compound.

## 1. Ionic and covalent bonds: from zero




## 2. Metal plus poison gas

Predict: what holds sodium and chlorine together in table salt?

- A pair of electrons shared by the two atoms
- Attraction between a positive ion and a negative ion ✓
- Nothing: they are only mixed

Sodium gives an electron to chlorine, forming a positive sodium ion and a negative chloride ion. The attraction between these opposite ions, the ionic bond, holds table salt together.

[ar-EG] الـ sodium بيدّي electron للـ chlorine، فيتكوّن positive ion من الـ sodium و negative ion من الـ chlorine. والتجاذب بين الـ ions دي، اللي هو الـ ionic bond، هو اللي ماسك ملح الطعام في بعضه.
## 3. Ionic bond

Electron transfer in sodium chloride Ionic bond The electrostatic attraction between a positive ion and a negative ion, formed by transfer of electrons. Both ions now have a stable outer level, like a noble gas.


## 4. Covalent bond

Two chlorine atoms share one pair of electrons in $\ce{Cl2}$ Covalent bond A bond formed by sharing pairs of electrons between two atoms. Each chlorine atom has 7 outer electrons and needs one more. Neither gives one away, so they share a pair.


## 5. Transfer or share?

Sort each substance by the bond between its atoms.


## 6. Summary

Ionic bond: one atom gives electrons, the other takes them; the oppositely charged ions attract. Covalent bond: two atoms share pairs of electrons. Next: metal atoms bond to each other in a third way, the metallic bond. Can you explain why sodium and chlorine form ions, but two chlorine atoms share? Sodium loses its 1 outer electron and chlorine gains it: $\ce{Na+}$ and $\ce{Cl-}$ form and attract. Each chlorine atom has 7 outer electrons and needs one more, so two chlorine atoms share a pair.



Chapter: Transition Elements (https://yaani.ai/en/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/en/lesson/chem-s3-en.lesson-bond.chemical-bond-basic