AQA A level Chemistry Bonding (chemrevise) Questions and Answers

AQA A level Chemistry Bonding (chemrevise) Questions and Answers What is Ionic bonding? electrostatic force of attraction between oppositely charged ions formed by electron transfer When do metal atoms form an ion with a ve+ charge? when they lose electrons When do non-metal atoms form an ion with a ve- charge? when they gain electrons When is ionic bonding stronger and melting points higher? -ions are smaller -ions have higher charges What is a covalent bond? shared pair of electrons When does a dative covalent bond form? shared pair of electrons in the covalent bond come from only one of the bonding atoms What is a dative covalent bond also called? co-ordinate bonding What are common examples of molecules with dative covalent bonding? NH4+ , H3O+ , NH3BF3 What is metallic bonding? electrostatic force of attraction between the positive metal ions and the delocalised electrons What 3 main factors affect metallic bonding? -Number of protons/ Strength of nuclear attraction -Number of delocalised electrons per atom -Size of ion How does Number of protons/ Strength of nuclear attraction affect the strength of the metallic bond? more protons the stronger the bond How does Number of delocalised electrons per atom affect the strength of the metallic bond? more delocalised electrons the stronger the bond How does the Size of ion affect the strength of the metallic bond? smaller the ion, the stronger the bond What bonding is found in a giant ionic lattice? Ionic What are examples of giant ionic lattices? sodium chloride, magnesium oxide What bonding is found in simple molecular structures? covalent What other forces are found in simple molecular structures between molecules? intermolecular forces (van der Waals, permanent dipoles, hydrogen bonds) What are examples of simple molecular structures? Iodine, Ice, Carbon dioxide, Water, Methane What bonding is found in macromolecular structures? covalent What are examples of macromolecular structures? Diamond, Graphite, Silicon dioxide, Silicon What bonding is found in giant metallic lattices? metallic What are examples of giant metallic lattices? magnesium, sodium (all metals) Why do ionic structures have high boiling/melting points? giant lattice of ions with strong electrostatic forces between oppositely charged ions Are ionic structures soluble in water? generally yes Why is conductivity in ionic structures poor when solid? ions can't move/ fixed in lattice Why is conductivity in ionic structures good when molten? ions can move What is the general description of ionic structures? crystalline solids Why is the melting/boiling points in simple molecular structures low? weak intermolecular forces between molecules (specify type e.g van der waals/hydrogen bond) What is the solubility in water like in simple molecular structures? poor Why is conductivity in simple molecular structures poor when solid? no ions to conduct and electrons are localised (fixed in place) Why is conductivity in simple molecular structures when molten? no ions What is the general description of simple molecular structures? mostly gases and liquids Why is boiling/melting points high in macromolecular structures? many strong covalent bonds in macromolecular structure. Take a lot of energy to break the many strong bonds What is the solubility in water like in macromolecular structures? insoluble Why is the conductivity of diamond and silicon dioxide poor? electrons can't move (localised) Why is the conductivity of graphite good? good as free delocalised electrons between layers What is the conductivity of macromolecular like when molten? poor What is the general description of macromolecular structures? solids Why is boiling/melting point high in metallic structures? strong electrostatic forces between positive ions and sea of delocalised electrons What is the solubility of water in metallic structures? insoluble Why is the conductivity of metallic structures good when solid? delocalised electrons can move through structure What is the conductivity of metallic structures like when molten? good What is the general description of metallic structures? shiny metal Why are metallic structures malleable? positive ions in the lattice are all identical. So the planes of ions can slide easily