Presentation on theme: "Hybridisation Some atoms form a different number of covalent bonds than the electron configurations of those atoms might suggest they should form."— Presentation transcript:
1hybridisationSome atoms form a different number of covalent bonds than the electron configurations of those atoms might suggest they should form.
2hybridisationIn general, when we look at the electron configuration for an atom, we can infer they type of bonding that it will undergo. However, certain atoms like carbon, beryllium, and boron, react differently than is expected.
3hybridisationCarbon has an electron configuration of 1s22s22p2. That indicates that there are 4 electrons in its valence shell. The 2s orbital is full, and there are there are 2 half-filled p-orbitals.
4hybridisationThe two half-filled p-orbitals would suggest that carbon would form two covalent bonds. However, scientific research proves otherwise.
5hybridisationIt appears that carbon will “promote” one of the electrons from the 2s orbital to the 2p orbital, leaving it with 4 half-filled orbitals. This gives carbon the ability to form 4 covalent bonds.
6hybridisationChemists describe this unusual behavior as hybridisation. Hybridisation is the rearrangement of electrons within the valence orbitals of atoms during a chemical reaction.
7HybridisationIn carbon, the four half-filled orbitals all have identical energies, and each is referred to as an sp3 hybrid orbital. There are a total of 4 sp3 hybrid orbitals, as is illustrated by adding the superscripts (a 1 is assumed for the s).
8HybridisationOnce hybridisation has taken place, any one of the four is equivalent to any other. All four orbitals have new bond characteristics that are different from the characteristics of the s and p orbitals.
9hybridisationhybridisation also occurs in compounds of beryllium. The electron configuration if Be is 1s22s2. It would appear to have no half-filled orbitals with which to form covalent bonds.
10hybridisationHowever, Be can form 2 covalent bonds by “promoting” one of the electrons in the 2s orbital into the 2p orbital, giving it 2 half-filled orbitals.
11hybridisationThe new half-filled orbitals formed by Be are referred to as sp hybrid orbitals. There are 2 sp hybrid orbitals.
12hybridisationBoron also undergoes a type of hybridisation. The electron configuration of B is 1s22s22p1. Boron will promote one of the 2s electrons, giving it 3 half-filled orbitals in its valence shell, allowing it to form 3 covalent bonds.
13hybridisationThis kind of hybridisation is referred to as sp2 hybridisation.
14Metallic BondingMetallic atoms, which have few valence electrons and low ionization energies, cannot achieve the inert gas configuration by sharing electrons or donating them to other metallic atoms.
15Metallic BondingTherefore, neither ionic nor covalent bonding is possible between metallic atoms. However, a relatively strong type of bonding, called metallic bonding, does occur in metals.
16Metallic BondingMetals consist of a crystalline lattice in which positive ions are arranged in fixed patterns, and the valence electrons are free to move. These electrons do not belong to individual atoms, but rather to the crystal as a whole.
17Metallic BondingThe “sea of electrons” produces an attractive force that fixes the positions of the metallic ions. Because the electrons can move about freely, metals are good conductors of heat and electricity.