Chemistry Notes PDF

ATOMIC STRUCTURE: ================= - - ATOMIC RADIUS: ============== - FACTORS AFFECTING ATOMIC RADIUS: Nuclear charge ↑ ↓ Atomic radius Shielding effect ↑ ↑ Atomic radius TREND: IONIC CHARGE: =============  IONIC SIZE: =========== → More shells present I...

ATOMIC STRUCTURE: ================= - - ATOMIC RADIUS: ============== - FACTORS AFFECTING ATOMIC RADIUS: Nuclear charge ↑ ↓ Atomic radius Shielding effect ↑ ↑ Atomic radius TREND: IONIC CHARGE: =============  IONIC SIZE: =========== → More shells present IONISATION ENERGY: ================== **First Ionisation Energy** -- energy required to remove one mole of electron from one mol of gaseous atoms to form one mol of gaseous positive ions A/~(g)~ → A/ ^+^~(g)~ + ē 1^st^ I.E **Second Ionisation Energy** -- energy required to remove one mole of electron from one mole of gaseous unipositive ions to form one mole of gaseous bipositive ions - - TREND:  Increases across the period FACTORS AFFECTING IONISATION ENERGY: Atomic size ↑ ↓ Ionisation energy Nuclear charge ↑ ↑ Shielding effect ↑ ↓ ELECTRONEGATIVITY: ================== **Electronegativity** -- ability of an atom to attract a pair of electrons towards itself in a covalent bond TREND: FACTORS AFFECTING ELECTRONEGATIVITY: Atomic size ↑ ↓ Electronegativity Nuclear charge ↑ ↑ Shielding effect ↑ ↓  ELECTRONEGATIVITY AND BONDING: IONIC BONDING: - - - - - - - - DATIVE COVALENT BONDING/CO-ORDINATE BONDING: - - - - METALLIC BONDING: - PROPERTIES: - - - FACTORS AFFECTING METALLIC BONDS: Number of delocalised electrons ↑ ↑ Metallic bonding Charge of ion ↑ ↑ Ionic size ↑ ↓ HYBRIDIZATION: ============== **Hybridization** -- phenomenon in which orbitals of approximately same energy mix up to give equal number of new hybrid orbitals of identical shape and equivalent energies SIGMA AND PI BONDS: SIGMA BONDS (σ): - - - PI BOND (π): - - - FACTORS AFFECTING REACTIVITY OF MOLECULE: Bond strength ↑ ↓ Reactivity\ → stronger bond keep molecules together Polarity of bond ↑ ↑ Sigma or Pi bond σ ↓\ → sigma bond is strong bond SP, SP^2^ AND SP^3^ HYBRIDIZATION: - - -  VALENCE SHELL ELECTRON PAIR REPULSION THEORY: ============================================= - - - SHAPES OF MOLECULES: ==================== NUMBER OF BOND PAIRS NUMBER OF LONE PAIRS SHAPE OF MOLECULE EXAMPLES ---------------------- ---------------------- ---------------------- ---------- 2 0 Linear BeF~2~ 3 0 Trigonal planar BF~3~ 4 0 Tetrahedral CH~4~ 5 0 Trigonal bipyramidal PC/~5~ 6 0 Octahedral SF~6~ 2 2 Angular bend H~2~0 3 1 Trigonal pyramidal NH~3~ 4 2 Square planar PtC/~4~   INTERMOLECULAR FORCES: ====================== **Bond energy** -- energy required to break one mole of a given covalent bond in gaseous state **Bond length** -- internuclear distance between two covalently bonded atoms - - - - - - - - PERMANENT DIPOLE PERMANENT DIPOLE FORCES: - - - - - HYDROGEN BONDING: - - - - KINETIC THEORY OF GASSES: ========================= - - - - - - → Caused by low force of attraction between molecules IDEAL GAS EQUATION: SIMPLE VS GIANT MOLECULES: ========================== SIMPLE MOLECULES: - - PHYSICAL PROPERTIES OF SIMPLE MOLECULES: - - - - - - HYDROGEN BONDED LATTICE:  - - - GIANT COVALENT MOLECULES: - - - - DIAMOND: - - - - - - - - - ALLOTROPES: **Allotropes** -- different molecular forms of same element FULLERENES: - - - - GRAPHENE: - - - - EXOTHERMIC AND ENDOTHERMIC REACTIONS: ===================================== EXOTHERMIC: **Exothermic reaction** -- a reaction that releases heat to its surroundings ENDOTHERMIC: **Endothermic reaction** -- a reaction that absorbs heat from its surrounding  ENTHALPY CHANGES: ================= **Enthalpy change** -- energy exchange between a chemical reaction and its surroundings at constant pressure **Standard enthalpy change of reaction (ΔH~r~^⦵^)** -- standard enthalpy change when the amount of reactant shown in stoichiometric equation react to give products under standard conditions **Standard enthalpy change of formation (ΔH~f~^⦵^)** -- standard enthalpy change when one mol of a compound is formed from its elements under standard conditions **Standard enthalpy change of combustion (ΔH~c~^⦵^)** -- standard enthalpy change when one mol of a substance is burnt in excess oxygen under standard conditions → product is H~2~O and CO~2~ **→** exothermic **Standard enthalpy change of neutralisation (ΔH~neut~^⦵^)** -- standard enthalpy change when one mol of water is formed from the reaction of an acid and an alkali under standard conditions → product is salt + H~2~O **Standard enthalpy change of solution (ΔH~sol~^⦵^)** -- standard enthalpy change when one mol of solute is dissolved in a solvent to form an infinitely dilute solution under standard conditions **Standard enthalpy change of atomisation (ΔH~at~^⦵^)** -- standard enthalpy change when one mol of gaseous atoms is formed from its elements under standard conditions **Standard enthalpy change of hydration of an anhydrous salt (ΔH~hyd~^⦵^)** -- standard enthalpy change when one mol of a hydrated salt is formed from one mol of anhydrous salt under standard conditions STANDARD CONDITIONS: - - - - MEASURING ENTHALPY CHANGES: =========================== q = -mcΔT q → heat transferred (J) m → mass of water (g) c → constant (4. 18 J g^-1^ 'C^-1^) T → temperature change ('C) HESS'S LAW: =========== **Hess's Law** -- total enthalpy change in a chemical reaction is independent of the route by which chemical reaction takes place as long as the initial and final conditions are the same  BORN HABER CYCLE: =================  **First enthalpy** **change** is always enthalpy of formation ORDER OF BORN HABER CYCLE: 1. 2. 3. 4. 5. 6. LATTICE ENTHALPY: ΔH latt Exothermic FACTORS AFFECTING: - - **Higher** lattice enthalpy = **stronger** ionic bonding ENTHALPY CHANGE OF FORMATION: ELECTRON AFFINITY: → 1 mol of electron is added to neutral gaseous atoms ΔH ea C/ (g) + e → C/- (g) ΔH ea 1 C/- (g) + e → C/ 2- (g) ΔH ea 2  ENTHALPY CHANGE OF ATOMISATION: COLLISION THEORY: ================= → Particles **must collide before a reaction can take place** → **Not all collisions lead to a reaction** → Reactants must possess a minimum amount of energy, **activation energy** → Particles must have **correct orientation**, approach each other in a certain way FACTORS AFFECTING RATE OF REACTION: ==================================== **Concentration of reactant ↑ ↑** **Rate of Reaction** **Surface Area of solids** **↑ ↑** **Temperature** **↑ ↑** **→** More temperature = more kinetic energy = more collisions **→** Remain unchanged at the end of reaction MAXWELL BOLTZMANN DISTRIBUTION CURVE: ===================================== **Maxwell Boltzmann** -- graph which shows the distribution of particles which has a specific amount of energy in a sample  FEATURES OF THE GRAPH: - - - - - - WHAT CAN BE CONCLUDED FROM THE GRAPH: - - - - - TEMPERATURE EFFECT ON GRAPH: - - - - - - - - - - - -  CATALYST EFFECT: - CATALYSIS: ========== **Catalyst** -- substance that provides an alternate reaction pathway with a lower activation energy Homogeneous catalyst: → Catalyst is in same phase to reactants (enzyme) Heterogeneous catalyst:\ → Catalyst is in different phase to reactants\ \ ENZYME CATALYSTS:\ \ → Enzymes = biological catalysts\ \ More efficient than inorganic catalysts\ → Reaction rate is increased by 10^6^ to 10^12^ Very specific\ → Specific substrate has specific enzyme No byproducts produced Enzymes work under mild conditions\ → 35'C\ → Atmospheric pressure → pH 7 **Activation Energy** -- minimum amount of energy required for a reaction to take place FINDING RATE OF REACTION: ========================= **The rate equation** -- links the rate of reaction to the concentration of reactants (mol d\^-3 s\^-1) **Order of reaction** -- how much the concentration of a reaction affects the rate **Individual order** -- power to which the concentration is raised in the rate equation **Overall order** -- sum of all the individual orders in the rate equation SECOND ORDER:\ \ - When the original concentration doubled lead to quadrupled rate  Second order in respect with reactant ZERO ORDER: - Zero order in respect with the reactant