Rate of Reaction: Change in concentration of a reactant used up or product formed in a given time. • Calculating Rate of Reaction: Rate (mol dm-3 s -1 ) = change in concentration (mol dm-3 ) / time (s). Time on x axis. • Working out rate of anything is change in...
Catalyst: A catalyst provides an alternative reaction pathway for reaction with lower activation energy. Catalyst regenerated/ not used up. Increases rate of reaction. Enthalpy Profile Diagrams: Reactants and product should be shown at correct levels with respect to...
Elastic Collisions: Molecules in gas move at high speed and collide with each other. Collisions are elastic as molecules do not slow down as a result of collision so no energy lost. • Energy of Molecules: In gas, liquid, or solution, some molecules move slowly with...
Reversible Reactions: A reaction that takes place in both forward and reverse directions if reversible. Equilibrium only in reversible reactions. • Dynamic Equilibrium System: Equilibrium that exists in a closed system when rate of forward reaction is equal to rate of...
Properties of alcohols - alcohols are polar due to the electronegative hydroxyl group(-OH) which pulls the electrons away from the carbon atom in the C-OH bond. The electronegative oxygen in a polar hydroxyl group draws electron density away from the hydrogen in the...
Substitution reactions of haloaklanes: When a haloalkane is reacted with hot aqueous alkali, a nucleophilic substitution occurs. It must be refluxed. To test for the rate of hydrolysis of C-halogen bonds: 1. Add water, to react with the haloalkane to form an alcohol....
Relative Mass: No units as it is ratio of two masses- it’s relative. • Carbon-12 Isotope: One atom of carbon 12 is 12 atomic mass units. 1 atomic mass unit is 1/12th of an atom of carbon- 12 = mass of a proton or neutron. • Relative Isotopic Mass: It is the mass of an...
Ion Charges: Group 1 = 1+ ions etc. Group 7 = 1-. • Need to know also Zn2+ and Ag+ . • Transition Metals: Form several ions with different charges. Ionic charge shown with Roman numeral in name. • Binary Compound: Compounds containing two elements. For the second...
Avogadro Constant: One mole = 6.02 x1023 particles, easier way to count number of particles. As mole linked to carbon- 12. 1 mole in grams = relative atomic mass. • Number of atoms = 6.02 x1023 x molar mass. 0.12 moles of S8 molecules means need to multiply by 8 as...
Molecular Formula: Covalent compounds and elements exist as molecules. • Empirical Formula: It is the simplest whole number ratio of atoms of each element in a compound. Used for giant structures of metals and ionic. • Relative Molecular Mass: Mr. Add relative atomic...
Water of Crystallisation: Water molecules that are bounded into crystalline structure of a compound. • Dot or .xH2O shows number of waters of crystallisation. Anhydrous means no waters of crystallisation. • Copper (II) Sulphate: When blue crystals of hydrated copper...
1 cm3 = 1 ml. 1dm3 = 1000 cm3 . • Concentration: Unit mol dm-3 . It is the amount of solute, in moles, dissolved in each 1 dm3 of solution. • Calculating Moles with Volumes: Moles (mol) = Concentration (mol dm-3 ) x Volume (dm3 ). If in cm3 / 1000 = dm3 . Standard...
Gas Volumes: At the same temperature and pressure, equal volumes of different gases contain same number of molecules. • Molar Gas Volume: Vm. It is the volume per mole of gas molecules. Volume of gas depends on pressure and temperature. • RTP: At RTP, 1 mole of gas...
Stoichiometry: The ratio of moles of each substance in a chemical reaction. • Balanced Equation: The balancing numbers gives molar ratio. • Find Moles- Various States: Can have solid go to gas or liquid. If asks to calculate volume of gas, remember there might be more...
Acids: Solid H2SO4 not an acid, when aqueous it is an acid. They ionise into (2)H + and SO4 2 . Need to know acids- HCl, H2SO4, H3PO4, HNO3 and CH3COOH. • Strong Acid: When dissolved in water, a strong acid completely dissociates in aqueous solution, releasing H + . •...
Titrations: Technique used to accurately measure the volume of one solution that reacts exactly with another solution. Used to find concentration of solution, identify unknown chemicals and find purity of substances. • Volumetric Flask: They make up standard solutions...
Oxidation Number: Aka oxidation state. Oxidation number sign placed before the number, unlike ionic. • Rules in Most Cases: - Elements- Oxidation number is zero. Even Cl2. - Most Metals- Oxidation number of group 1, 2 and 3 same as ionic charge, +1 or +2 or +3. Look...
Shells are energy levels. • Atomic Orbitals: It is region around a nucleus that can hold up to two electrons, with opposite spin. Must have opposite spin due to repulsion between two negative electrons. • Four Different Atomic Orbitals: s-, p-, d- and f-. The greater...
Bonding Questions: E.g. melting point question ‘in terms of bonding and structure.’ - Name structure. - Name bond. - Write what the attraction is between e.g. + metal ions and –ve delocalised electrons in metallic, atoms in covalent bond and molecules in simple...
Relative: Subatomic particles have tiny masses so use relative masses instead of grams. • Electron: An electron has about 1/ 1800th mass of a proton, positioned in the shell. • Protons: Number of protons identifies element- atomic number, the number on top in periodic...
Covalent Bonding: It is the strong electrostatic force of attraction between a shared pair of electrons and the nuclei of the bonded atoms. Covalent bonding occurs between non- metallic elements and polyatomic ions. • Orbital Overlap: A covalent bond is the overlap of...
Alkenes Unsaturated hydrocarbon containing a σ bond (overlap of orbitals directly between the bonding atoms) and a π bond (sideways overlap of adjacent p-orbitals above and below the bonding C atoms) overlapping. Shape of alkenes - Trigonal planar shape with 120˚ bond...
Alkanes - saturated hydrocarbons containing single C-C and C-H bonds as σ-bonds with free rotation of the σ-bonds. Shape of Alkanes - tetrahedral with bond angle 109°. Electron pairs repel. lone pairs repel more than bonded pairs. Boiling points of alkanes - longer...
No. of carbons: meth- 1, eth- 2, prop- 3, but- 4, pent- 5, hex- 6, hept- 7, oct- 8, non- 9, dec- 10 Nomenclature IUPAC rules for naming organic compounds; count carbons on longest carbon chain use functional groups as prefixes or suffixes other side chains are...
The periodic table and periodicity Describe the arrangement of the periodic table. The periodic table arranges elements in order of increasing atomic (proton) number. The table is further arranged in periods showing repeating trends in physical and chemical properties...
The shapes of simple molecules and ions Predict the shape and bond angle of ____. _____ because it has n of electron pairs and n lone pairs. Electron pairs repel to become as far apart as possible. Lone pairs of electrons repel more strongly than bonding pairs. Draw...
Shapes of molecules and intermolecular forces Define ionic bonding An ionic bond is the electrostatic force of attraction between positive and negative ions Explain the solid structures of giant ionic lattices This is a result of oppositely charged ions strongly...
Acids and redox Explain the difference between acids, bases and alkalis. Acids dissolve in water and release H+ ions in aqueous solution. They are proton donators. A base neutralises an acid to form a salt. Alkalis are water-soluble bases that dissolve in water to...
Describe the techniques and procedures used when preparing a standard solution of required concentration and carrying out acid–base titrations. A standard solution is a solution with a known concentration. Weigh the solid substance and divide this number by its...
Electrons and bonding Describe the number of electrons that can fill the first four shells. 1st shell = 2 2nd shell = 8 3rd shell = 18 4th shell = 32 Define atomic regions / orbitals. A region...
Amount of Substance Define relative isotopic mass. The mass of an isotope relative to 1/12 of the mass of an atom of carbon-12. Define relative atomic mass. The relative atomic mass is the weighted mean mass of an atom of an element relative to 1/12 of the mass of an...