Chem a level
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Chem a level - Details
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| 🇬🇧 | 🇬🇧 |
| Sulfuric acid | H2SO4 |
| NItric | HNO3 |
| SULFATE | SO4(2-) |
| NITRATE | N03(-) |
| CARBONATE | C03(2-) |
| HYDROXIDE | 0H- |
| OXIDE | 02- |
| PHOSPHATE | PO4(3-) |
| NITRIDE | N3- |
| Acid + metal = | Salt + hydrogen |
| Acid + metal oxide = | Salt + water |
| Acid + metal hydroxide | =salt + water |
| Acdid + metal carbonate | Salt + water + c02 |
| Triangle ------ mass= | Moles x mr |
| Triangle ------moles= | Mass/mr |
| Triangle ------ mr= | Mass/moles |
| Cm moles= | C x v /1000 |
| Cm v= | Nx1000 /c |
| Cm c= | N x10000/ v |
| Gases at rtp. moles= | Vx24000 or v x 24 (DM) |
| Gases at rtp volume= | N/24000 or n/24 |
| Pressure. killer pascal into pascals | You divide by 1000/ 10-3 |
| Volume is measured in m3 so | Dm -m divide by 10-3 cm-m divide by 10-6 |
| R = gas constant = | 8.314 |
| No of particles | N x 6.02 x 10-23 |
| Finding a relative molecular mass in gass eq | 1. Conversions 2.work out what you know 3. figure out eq ( pv=nrt) or (n=vx24000 or 24) 4. work out your moles for the eq mr= m/n |
| Stoichiometry | The ratio of the balanced equation |
| Reacting masses | 1. work out the moles of the info provided 2. check the stoichiometry ratio to see if it needs x or / 3. then put in m=nxmr or different for gas or conc |
| Unknown metal | 1. work out moles 2. check stoich 3. work out moles/ mass = mr 4. periodic table |
| Percentage yield | Actual yield/ theoretical yield x 100 1. work out the moles of both depending on the question may have to work backwards |
| Atom Economy | Sum of molar mass of desired / sum of molar mass of all products x 100 x + x = h + co2 h/ co2 + h for substainability |
| Strong acid | H+ ions completely dissoaciates |
| Weak acids | Partially dissociates |
| Base | Proton acceptor |
| Acid | Proton donor |
| Ionic equations | Solids- don’t split Liquids - don’t split Gases don’t split Aqueous split |
| Standard solution in buriet | Divide by mean titre |
| Standard solution in conical flask | Divide by 25 cm |
| Mean tire | Put 23.0 |
| ./. Uncertainty | Uncertainty/ volume measured x 100 |
| Advragodo constant = | 6.02 x 1023 |
| Moles = | Mass/mr |
| Mass= | Mr x moles |
| Mr= | Mass/moles |
| Empirical formulae | The simpler ratio |
| Molecular formula | Actual ratio |
| Water crystallisation | C-a= Anhydrous B-C=Water |
| The columns /groups 3-8 are known as the | ... p block |
| The definition of an Atomic orbital is | Shells are made up of atomic orbitals. An atomic orbital is the region around the nucleus that can hold up two electrons with opposite spins. |
| S orbital | S= sphere each shell contains 1s orbital 1st shell contains only s ( 1s1 1s2) |
| P orbitals | Shape = dumb bell each shell from the 2nd contains 3p orbitals with 2 electrons in each so in tot 6 e ( 1s22s22p6) |
| Shell 3 | Consist of p and s orbitals with a higher energy level |
| D orbitals | - 5 d orbitals so 10 electrons |
| Working out amount of electrons by sub shells present | S=2 p=6 d=10 f=14 |
| When it gets to the 4th shell they is | ... backfilling by the 3d block due to 3d having higher energy than 4s subshell |
| Electron pairing occurs when | Two electrons are in opposite spin as they are both negatively charged to counteract repulsion |
| Short hand configuration | The last electron from group 8 goes in square brackets [ne]1s2 |
| Orbital = | 2 electrons |
| N=4 shell | They are 4 sub shells s,p,f,d so 2+6+10+14 =32 |
| Definition of ionic bonding | Electrostatic attraction between oppositely charged ions |
| Things to remember in dot and cross diagrams | - square brackets [] - can put a big 2 or n number infront of brackets - remember the charges on the outside of [] |
| Structure of an ionic compound | Each ion attracts oppositely charged ions in all directions resulting in a giant ionic lattice. |
| Properties of ionic compound | -solid at rtp due to insufficient energy to overcome the strong electrostatic forces of attraction between oppositely charged ion . so high temp needed so HIGH MELTING AND BOILING POINT -soluble in polar solvents (charged) - Electric conductivity inn liquid state as ions are delocalised and free to move as charge carriers |
| Definition of covalent bonding | The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom |
| A covalent bond is localised due to | The attraction solely between the shared pair of electrons and nuclei of the two bonded atoms |
| A rule in covalent bonding diagrams | A central atom doesn't have to have 8 electrons |
| What is this picture showing at O=O | DOUBLE COVALENT BOND |
| The nitrogen bonding is what type | TRIPLE COVALENT BONDING |
| Dative covalent bonds | When the shared pair of electrons comes from the one/same element |
| Electron pair repulsion theory states | Negative charge - repulsion The electrons surrounding the central atom determine the shape of the molecules. As they repel they are arranged as far apart as possible so the arrangement lowers repulsion |
| Tetrahedral | 4bonding regions 109.5 degrees |
| Pyramidal | 3 bonding regions 1 lone pair 107 degrees |
| Non linear | 2 bonding regions 2 lone pairs 104.5 degrees |
| Linear | 2 bonding region 180 degrees |
| Triagonal planar | 3 bonding regions 120 degrees |
| Octahedral | 6 bonding regions 90 degrees |
| Electronegativity definition | The attraction of a bonded atom for the pair of electron in a covalent bond |
| Factors affecting electroegatvity | - The nuclear charges are different - The atoms may be different sizes -The shared pair of electrons may be closer to nucleus than the other |
| ELECTRONEGATIVITY DIFFERENCE 0= | COVALENT |
| EN DIFFERENCE +1.8 = | IONIC |
| AN ELECTRONEGATIVITY DIFF BETWEEN 0-1.8= | POLAR COVALENT |
| Non polar bonds terms | Bonded atoms are the same or same or siimiliar electronegativity |
| Delta + and delta - are given | Larger e neg gets delta - smaller e neg gets delta + |
| Which molecules have an overall dipole | Non-symmetrical molecules so polar molecules have a dipole overall eg. pyramidal and non linear |
| Polar covalent bond definition | Shared paired of electrons where the electron is not shared equally so e neg difference |
| Dipole definition | Charged separation across a bond with one atom having a delta + charge and one item with delta - charge |
| IMF definition | Weak interactions between dipoles of a different molecules |
| Types of IMF | Induced dipole-dipole (LONDON) permanent dipole-dipole Hydrogen bonding |
| What are IMF responsible for | Melting and boiling ptts and density |
| London forces... | ... Electrons move causing uneven distribution ... a tempory instantaneous dipole is set up in one molecule... induces a temp dipole in adjacent molecule hence the attraction |
| Permanent dipole-dipole interactions | -asymmetrical -polar -forever |
| Simple Molecular substance is | Small units containing a definte number of atoms |
| Properties of simple MS | -low melting and boiling point due to weak intermolecular forces -covalent bonds do not break -soluble in non polar soluvents - hexane -non conductors of electricity - fixed p and no charged carriers |
| Why don't Simple MS dissolve in water | Little interaction between the molecules in the lattice and the polar solvent molecules |
| Hydrogen bonding | The lone pair on the electronegative atom on one molecule and the electron deficient hydrogen on an adjacent molecule |
| Elements are arranged by the | Increasing atom number |