1. Covalent bonding: Overlapping of 2 half filled orbitals Gases

2. H 2 covalent bonding ↑ ↓ ↑ ↓ 1s H atom H 2 molecule Couper: H – H (single bond, weak bond) Lewis:

3. O 2 covalent bonding ↑ ↓ ↓ ↓ 2p O atom O 2 molecule ↑↑ ↑ ↓ 1s 2s 2p ↓ ↑ ↓ 1s 2s ↑ ↓ ↓ Couper: O = O (double bond, stronger than H 2 with single bond) ↑↑ ↓ Lewis:

4. H 2 O covalent bonding ↑ ↑ ↓ ↓ 2p 1 O atom2 H atoms H 2 O molecule ↑↑ ↑ ↓ 1s 2s ↓ 1s :H ↓ ↑↑ ↓ Lewis: Couper:

5. CO 2 covalent bonding ↑ 2p 2 O atoms 1 C atom CO 2 molecule ↓ ↓ ↑ ↓ 1s 2s ↑ ↓ ↓ 2p ↑ ↑ ↑↓↑↓ ↑↓↑↓ 1s 2s ↑ ↑ ↑ 2p ↑ ↑ ↓ 1s 2s ↓ ↑ ↓ ↑ ↓ Lewis: Couper: O = C = O (2 double bonds – linear molecule) Excited electron