Chemistry AQA AS EXAM 2024 QUESTIONS WITH 100% CORRECT ANSWERS

Mass number - ANSWERS Total number of protons and neutrons. Atomic number - ANSWERS Numbers of protons in the nucleus and number of electrons in shells. Negative Ions - ANSWERS More electrons than protons. Positive ions - ANSWERS More protons than electrons. Relative isotopic mass - ANSWERS mass of an atom of an isotope of an element on a scale where an atom of carbon12 is 12. Relative atomic mass - ANSWERS average mass of an atom of an element on a scale where an atom of carbon12 is 12. Relative molecular mass - ANSWERS average mass of a molecule on a scale where an atom of carbon12 is 12. First ionisation energy - ANSWERS the energy needed too remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions. Second ionisation energy - ANSWERS the energy needed to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions. Number of particles= - ANSWERS Number of moles x Avagadros constant (6.02 x 10^23) Number of moles= - ANSWERS Mass / Mr Number of moles= - ANSWERS Concentration (moldm^-3) x Volume (dm^3) Methyl orange indicator - ANSWERS yellow in acid, red in alkali. Commonly used in titrations. Phenolphthalein indicator - ANSWERS pink in alkali, colourless in acid. Commonly used in titrations. Avogadros constant - ANSWERS the number of atoms in 12g of carbon12 (6.02 x 10^23) Ideal gas equation - ANSWERS Pv= nRT Empirical formula - ANSWERS simplest whole number ratio of atoms of each element in a compound. Molecular formula - ANSWERS gives the actual numbers of each element in a molecule. Percentage yield - ANSWERS how much product was actually made compared with the amount of product that was expected theoretical yield - ANSWERS the maximum mass of product expected in a reaction. actual yield - ANSWERS the mass of product that is actually obtained in a reaction. Atom economy - ANSWERS measure of the efficiency of a chemical reaction. The proportional mass of reactants that actually become part of the desired product in a balanced chemical equation. Ionic bonding - ANSWERS Ions (metal and non metal) are held together by electrostatic forces of attraction due to the transferring of electrons. Eg: Sodium chloride. Mass spectrometer - ANSWERS An instrument used to accurately determine the relative atomic mass. Separates atoms or molecules (gaseous positive ions) according to their charge and mass. Orbital - ANSWERS Region in space where one is likely to find up to two electrons with opposite spin. Covalent Bonding - ANSWERS holds molecules together by sharing electrons between non-metals. Eg: I2, Graphite, Diamond. Dative Covalent Bonding - ANSWERS Where both electrons are provided by one atom for a covalent bond. Linear molecule - ANSWERS 2 bonds 180 degree angles 2D e.g: CO2 Trigonal planar molecule - ANSWERS 3 bonds 120 degree angles 2D e.g: BF3 Tetrahedral molecule - ANSWERS 4 bonds 109.5 degree angles 3D e.g: CH4 Trigonal bipyramid molecule - ANSWERS 5 bonds 120 degree and 90 degree angles 3D e.g.: PCl5 Octahedral molecule - ANSWERS 6 bonds 90 degree angles 3D e.g.: SF6 Lone pairs - ANSWERS Cause a repulsion of 2.5 degrees. Charge Clouds - ANSWERS What bonding pairs and lone pairs exist as in a molecule. Largest repulsion angle in a molecule - ANSWERS lone pair - lone pair 2nd largest repulsion angle in a molecule - ANSWERS lone pair - bonding pair Smallest repulsion angle in a molecule - ANSWERS bonding pair - bonding pair Electronegativity - ANSWERS An atoms ability to attract the electron pair in a covalent bond Polar - ANSWERS caused by the difference in electronegativity in a covalent bond, where the electrons are pulled towards the more electronegative atom creating a dipole. Dipole - ANSWERS difference in charge between atoms created by a shift in electron density within the bond. Permanent dipole- dipole forces - ANSWERS weak electrostatic forces of attraction between polar molecules S- and S+ charges in their permanent dipoles. Van der Waals - ANSWERS The weakest intermolecular force formed between all atoms and molecules when temporary dipoles are formed and attracted (due to fast electron movement in charge clouds) Hydrogen bonds - ANSWERS Hydrogen covalently bonded to fluorine, nitrogen and oxygen. H atoms form bonds with lone pairs. High boiling and melting points. Metallic bonding - ANSWERS postive metal ions attracted to seas of negative delocalised electrons to form a regular lattice. HMP and HBP, conduct electricity. Enthalpy change - ANSWERS heat energy transferred in a reaction at constant pressure. Kjmol-1 Standard enthalpy of formation - ANSWERS the enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions Standard enthalpy of combustion - ANSWERS the enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions. Enthalpy - ANSWERS The heat content that is stored in a chemical system. q=mcDELTA