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Atomaire bindingen - ionische binding - covalente binding

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Presentation on theme: "Atomaire bindingen - ionische binding - covalente binding"— Presentation transcript:

1 Atomaire bindingen - ionische binding - covalente binding
- metallische binding

2 Ionic bonding 1 between a Li atom and a F atom E

3 Ionic bonding 2 E gives Li+ F- molecule Electron Affinity (EA)
Ionization Potential (IP) E Energy cost: DE = IP(Li) – EA(F)

4 Ionic bonding 3 Ionic binding curve: electron transfer Pauli repulsion
Coulomb attraction ions Binding curve has stable minimum !!

5 Ionic bonding 4 only works between very dissimilar atoms !!

6 Ionic bonding in solids
common salts have ionic bonding NaCl structure CsCl structure Cs+ Na+ Cl- Cl- structure determined by relative size ions

7 electron wants to pull wells close !!
Covalent bonding 1 Model system: one electron in two wells wells far apart wells close ES < EA electron wants to pull wells close !!

8 Covalent bonding 2 E H2 molecule: two electrons in two wells H atom
allowed by Pauli

9 Covalent bonding 3 E He2 molecule? four electrons He atom He2 molecule
no electronic bonding in He2 no stable He2 molecule !! because of Pauli exclusion principle

10 Hetero-atomic covalent bonding
H F molecule H atom F atom E polar bond !!

11 covalent bonding gives directional bonds !!
Poly-atomic covalent bonding 1 H2O molecule 2 2 covalent bonding gives directional bonds !!

12 Poly-atomic covalent bonding 2
CH4 molecule: tetraeder C hybrid orbital

13 Covalent bonding in solids
C, Si, ... have covalent bonding and compound semiconductors: GaAs, ... diamond structure

14 has a wave-like character (delocalized)
Metallic bonding in solids 1 metal: one electron in many wells positive ions has a wave-like character (delocalized)

15 'Fermiology'

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26 Twee verschillende metalen met elkaar in contact  contact-potentiaal

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28 Volgende (laatste) hoor-college:
Quantum theorie van electrische geleiding Isolatoren vs. (half)geleiders, supergeleiders Terugblik op de gehele stof


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