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Each H atom consists of a 1s electron in a spherical ______ orbital.
1s
H2 forms a ______ bond due to the overlap of 1s orbitals.
σ
The carbon atom in its ground state has the electron configuration [He]2s22px12py12pz0, which indicates it has ______ half-filled p orbitals.
two
In order to create four bonds, a carbon atom promotes a 2s electron into a higher energy ______ orbital.
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The energy investment to promote an electron is often recovered by ______ formation.
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After promotion, the carbon atom can form four ______ bonds with hydrogen.
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The 2s and three 2p orbitals of the promoted state of carbon hybridise to form four identical ______ hybrid orbitals.
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The sp3 hybrid orbitals point towards the vertices of a ______.
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In methane, the four C–H bonds are experimentally found to be ______.
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Hydrogen gas is represented chemically as ______.
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The hybridisation type for a molecule with 2 orbitals is ______.
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C atoms in ethene (C2H4) are ______ hybridised.
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For the molecule PCl5, the hybridisation type is ______.
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Ethylene (C2H4) exhibits a ______ geometry due to its sp2 hybridisation.
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In ethyne (C2H2), each C atom is ______ hybridised.
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The ______ bond in alkynes is formed by the overlap of sp hybrid orbitals.
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In aspirin (C9H8O4), the acetylsalicylic acid features ______ hybridised carbon atoms.
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A molecule with four electron pairs adopts a ______ hybridisation.
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Diborane (B2H6) contains ______ valence electrons.
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The hybridisation type that involves three regions of electron density is known as ______.
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The hybridised state of a carbon atom is represented as He1(sp3)1(sp3)1(sp3)1, which indicates its ______ character.
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Methane (CH4) has a molecular geometry that is described as ______.
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The hybridised state of nitrogen is represented as He2(sp3)1(sp3)1(sp3)1, which is typical of its presence in ______.
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Oxygen in water (H2O) has a hybridised state noted as He2(sp3)2(sp3)1(sp3)1, leading to an ______ shape.
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Carbon in the promoted state is represented as [He]2s12px12py12pz1, indicating that it is in a ______ state.
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In the context of sp3 hybridisation, carbon contributes 75% from ______ orbitals.
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Nitrogen's hybridisation results in a molecular shape characterized as ______ pyramidal.
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The molecular geometry of water is affected by the lone pairs on the ______ atom.
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In sp3 hybridisation, the carbon atom's electron configuration changes to involve ______ orbitals.
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The overall hybridisation of carbon leading to the formation of methane can be described as ______.
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Study Notes
H2 - σ Bond
- Each hydrogen atom consists of a 1s electron in a spherical 1s orbital.
- The 1s electron pair in H2 occupies a single orbital that spreads over both atoms, resulting in a sausage shape distribution of electrons - this is called a σ bond.
- The merging of the two orbitals is called orbital overlap.
Hybridisation - The C-atom
- A carbon atom in its ground state has the electron configuration [He]2s22px12py12pz0.
- This configuration suggests that carbon can only form 2 bonds, as only two p orbitals are half-filled.
- However, carbon needs to form 4 bonds to achieve stability, in order to complete its octet.
- This is achieved by promoting a 2s electron to a higher energy 2p orbital, resulting in the configuration [He]2s12px12py12pz1.
- This process requires energy, but this energy is recovered during bond formation, as shown in methane (CH4).
- The four C-H bonds in methane are equal in length and bond strength.
Hybridisation - sp3
- The 2s and three 2p orbitals in the promoted state of carbon hybridise to form four identical sp3 hybrid orbitals.
- These sp3 orbitals have 75% p-orbital character and 25% s-orbital character, giving them a tetrahedral shape.
- This allows carbon to form four equivalent σ bonds, leading to the observed tetrahedral geometry in molecules like methane.
Hybridisation - sp3: Nitrogen
- Nitrogen in its ground state has the electron configuration [He]2s22px12py12pz1.
- When nitrogen hybridises, it forms four sp3 orbitals, with 75% p-orbital character and 25% s-orbital character.
- The nitrogen atom in ammonia (NH3) has three sp3 hybrid orbitals that bond to hydrogen atoms, and one unhybridised sp3 orbital that forms a lone pair. This results in a trigonal pyramidal shape.
Hybridisation - sp3: Oxygen
- Oxygen in its ground state has the electron configuration [He]2s22px22py12pz1.
- When oxygen hybridises, it forms four sp3 hybrid orbitals, with 75% p-orbital character and 25% s-orbital character.
- The oxygen atom in water (H2O) has two sp3 hybrid orbitals that bond to hydrogen atoms, and two unhybridised sp3 orbitals that form lone pairs. This results in a bent or angular shape.
Hybridisation - Summary
- The type of hybridisation depends on the number of orbitals that are mixed.
Hybridisation Summary Table
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2 orbitals (1s, 1p): Linear, sp hybridisation.
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3 orbitals (1s, 2p): Trigonal planar, sp2 hybridised.
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4 orbitals (1s, 3p): Tetrahedral, sp3 hybridised.
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5 orbitals (1s, 3p, 1d): Trigonal bipyramidal, sp3d hybridised.
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6 orbitals (1s, 3p, 2d): Octahedral, sp3d2 hybridised.
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When more than four electron pairs are present in the valence shell of the central atom, d-orbitals are required, as seen in the case of phosphorus pentachloride (PCl5).
Hybridisation - sp2
- In ethene (C2H4), each carbon atom exhibits trigonal planar geometry. The molecule overall is also planar.
- The carbon atoms are sp2 hybridised, with one 2p orbital remaining unhybridised. These unhybridised p orbitals overlap sideways to form a π bond.
- Each sp2 orbital has a 67% p-orbital character and 33% s-orbital character.
- This results in three sp2 hybrid orbitals forming sigma bonds (σ) to three other atoms to form a trigonal planar geometry.
- These hybrid orbitals are in the same plane. The unhybridised p orbitals are perpendicular to this plane, leading to the formation of a π bond.
Hybridisation - sp2: Aspirin
- Aspirin contains sp2 hybridised atoms in its structure:
- The carbonyl groups within the molecule have sp2 hybridised carbons .
- This is due to the double bond present in the carbonyl group, which involves a sp2 hybridised carbon and an oxygen atom with lone pairs.
Hybridisation - sp
- In ethyne (C2H2), each carbon atom exhibits linear geometry.
- The molecule is also linear overall.
- The carbon atoms are sp hybridised, with two 2p orbitals remaining unhybridised. These unhybridised p orbitals overlap sideways to form two π bonds.
- Each sp orbital has a 50% p-orbital character and 50% s-orbital character, forming a linear geometry.
- The sp hybrid orbitals form sigma bonds (σ) along the axis, while the unhybridised p orbitals overlap to form two pi bonds (π) perpendicular to the central axis, resulting in a triple bond.
Hybridisation - sp3, sp2, sp: Terbinafine
- Terbinafine is a drug used to treat fungal infections.
- It is a complex molecule.
- It contains atoms with different hybridisations:
- sp3 hybridised carbon atoms (methylene groups).
- sp2 hybridised carbon atoms (adjacent to the double bond in the conjugated system, known as a trans-alkene).
- sp hybridised carbon atoms (triple bond, alkyne).
- sp3 hybridised nitrogen atoms (tertiary amine).
Molecular Orbital Theory Exceptions
- Diborane (B2H6) is an exception to the typical hybridisation rules.
- Boron has 3 valence electrons, therefore B2H6 has 12 valence electrons (2×(3×B)+6×(1×H)).
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Description
Explore the concepts of σ bonds and hybridization in chemistry, focusing on hydrogen and carbon atoms. Understand how orbital overlap and the hybridization of carbon allow it to form stable compounds like methane. This quiz covers essential principles for mastering molecular bonding.
