Consolidation

• protons no. increases, nuclear charge increases. • Shielding effect increases because the additional electrons are added to the inner 3d subshell. • increase in shielding effect cancels out the effect of the increase in nuclear charge. • effective nuclear charge and attraction for valence electrons remains fairly constant/ increases minimally (DOES NOT DECREASE!)

• e- removed from the 4s orbital • Across a period, proton number increases and nuclear charge increases. • e- added to 3d subshell, increase in number of inner 3d electrons, provide more shielding between the nucleus and the outer 4s electrons. • increase in shielding effect offsets the increase in nuclear charge • electrostatic attraction between the nucleus and outer 4s electrons increases minimally • Thus, energy required to remove the first electron is almost constant

• e- in 3d and 4s subshell are close in energy • both 3d and 4s electrons are available for delocalisation into the sea of electrons • number of delocalised electrons increases, charge density increases, metallic bonding is stronger in the transition elements

A transition element is a d-block element which can form one or more stable ions with a partially filled d subshell.

• both 3d & 4s e- similiar in energy, • e- in both 3d & 4s orbitals avaliable for for bond formation

• partially filled 3d subshell allows the exchange of e- to and from the reactant molecules • facilitate formation of weak bonds with reactant molecules

• ion or molecule containing at least one atom that has lone pair of e- • to be donated into a low-lying vacant orbital of metal atom or ion • forming a dative covalent bond • and forming a complex

• can exist in differnet oxidation states • convert from one oxidation state to another • due to the similar energy of the 3d and 4s orbitals • this facilitates formation & decomposition of intermediates

central metal ion linked to one or more ligands by dative covalent bonds.

• have low lying vacant orbitals to accommodate lone pair of e- from ligands to form dative covalent bonds (DCB) • small ionic radius and high charge density, → high polarising power and able to attract lone pair of e- from ligand to form DCB.

• in pesence of water ligands, partially filled 3d orbitals of TM split into 2 groups of different energy levels • e- that have lower energy d orbitals promoted to higher energy d orbitals as they adsorb energy from wavelength of visible light (d-d transitions) • colour observed is complementary to the wavelength of light absorbed

• Al3+ has a high charge density, • polarises and distorts e- cloud of water ligands, weakening OH bonds in water ligands, • water ligands becomes proton donors, aqua complex undergoes appreciable hydrolysis to give acidic solution (note: acidic sol will react with carbonates to from co2 efferversence!) [Al(H2O)6]3+ (aq) ⇌ [Al(H2O)5(OH)]2+ (aq) + H+ (aq) alcl3 hydrate in h2o to form aqua complex, aqua complex hydrolyse!!!!!

• different ligand cause different extents of d-d splitting in the TM • resulting different energy gaps between two levels of d-orbitals • electrons in lower energy d-orbitals promoted to different level as absorb different wavelengths of visible light • colour observed, which is complementary to the colour absorbed, is different.

• each C atom sp hybridised, one sp hybrid orbital overlaps head-on with the 1s orbital of H via σ-bond AND another sp hybrid orbital overlap head-on with sp hybrid orbital of another C atom via σ-bond • two unhybridised p-orbitals (IMPORTANT) of one C atom overlaps side-on with the two unhybridised p-orbitals of the other C atom to form 2 π-bonds. one unhybridised p orbital for one π-bond!!! normal carbon is sp3 hybridised!!!

• one s and one p orbital of atom mix to form sp hybrid orbitals • there are two unhybridised p-orbitals 2 unhybridised as original should be sp3 hybridised!!!

• balance O2 by adding H2O • balance H2 by adding H+ • balance charge by adding e-

• maintain electrical neutrality of each half cell • complete the circuit allowing ions to flow without mixing electrolytes

• kinetic factor not considered as E° cell measure POE, rxn thermodynamically feasible but not kinetically feasible • Rxn take place under non-standard conditions • side rxn can still occur

• partially filled 3d subshell allows the exchange of e- to and from the reactant molecules • facilitate formation of weak bonds with reactant molecules • reactants adsorbed onto the active sites of the catalyst surface by forming weak interactions with catalyst • This increases the surface concentration reactant on catalyst • Adjacent (different) reactant molecules are brought close tgt and correct orientation • This weakens the Intramolecular covalent bonds in the reactants resulting in lower activation energy than the uncatalysed reaction. • Products formed diffuse from the catalyst surface, vacant active sites regenerated for adsorbing other reactants

• Catalyst provides an alternative reaction pathway which of lowered activation energy. • Thus, particles with energy equal to or greater than the actvation energy of the catalysed reaction E a(cat) increases • This results in an increase in frequency of effective collisions, • This results in a larger rate constant, k hence rate of reaction increases.

• temperature increases, kinetic energy of reactant particles increases • more reactant particles have energy greater than or equals to the Ea of reaction • frequency of effective collisions increases, rate of reaction increases • rate constant also increases due to temp increase, increasing rate of reaction boltzman graph: Y axis: no. of particles with given energy X axis: kinetic energy label Ea and shade, rmb to write legend for graph shaded!

Down Group 2 from Ca to Ba, Ionic radii: Ca2+ : 0.099nm Sr2+ : 0.113nm Ba2+ : 0.135nm • charges stay the same but the ionic radii of the Group 2 cations, M2+ increases from Ca to Ba. • As charge density = charge / radius , there is a decrease in the **charge density **of the Group 2 cations. Hence, the polarising power of the Group 2 cations decreases • This results in the electron cloud of the large CO 3 2 – anion to be distorted (or polarised) to a smaller extent and a smaller weakening effect on the CO covalent bonds within the CO 3 2 – by the M2+ . • As more energy is required for decomposition (breaking down of the anion), the decomposition temperature increases from CaCO 3 to BaCO3 .

Al 3+ has high charge density/polarizing power which is able to polarise the electron cloud of O2− /anion , hence giving the oxide some covalent character. Therefore, Al2O3 has a giant ionic lattice structure with covalent character, making it an amphoteric oxide that reacts with both acids and alkalis.

MgO is an ionic oxide. Hence it is basic and is able to react with acids. MgO + 2HCl → MgCl2 + H2O SO 3 is a covalent oxide, hence it is acidic and is able to react with bases. SO3 + 2NaOH → Na2SO4 + H2O Al2 O3 : amphoteric oxide hence it react with both acids and bases. Al2O3 + 6HCl → 2AlCl 3+ 3H2O Al2O3 + 2NaOH + 3H2O → 2Na[Al(OH)4]