Aqa chemistry paper 1 Higher Exam 2025

Filtration - -It removes large, insoluble particles from a liquid. e.g. sand from water Evaporation/crystallization - -leaves behind crystals of a dissolved substance if heated gently Distillation - -condensing and evaporating a solvent and then collecting it Fractional distillation - -separates liquids due to their boiling points Chromatography - -causes a substance for rise up paper due to capillary action. Lighter particles move further up . Solid - -vibrate about fixed positions regular lattice arrangement cannot be compressed Liquid - -no regular arrangement and can move past each other cannot be compressed Gas - -particles are far apart move randomly at fast speeds can be compressed What is needed to overcome the electrostatic forces of attraction between the particles to melt/evaporate? - -heat energy What model of the atom did JJ Thomson design - -Plum pudding model. Sphere of positive mass and negative particles randomly inside. Ernest Rutherford - -discovered that the nucleus was small and postively charged by finding most alpha particles went straight through a gold leaf and few were deflected back. Neil’s Bohr - -dedecued that elections exist in shells. James chadwick - -determinded that the nucleus must contain neutrons as well as protons CHEMISTRY CHEMISTRY CHEMISTRY What did mendeleev do - -left gaps in his table for unknown elements and made predictions about their properties How was the periodic table ordered before mendeleev - -ordered by atomic weight due to having similar properties What are group 1 metals and their properties - -alkali metals They lose outer electron to form positive ions They are more reactive down the group as the electron is further away from the nucleus and the force of attraction is lost What are group 7 called and their properties - -halogens form -1 ions to gain a full outer shell less reactive as you go down the group and the boiling point increases Nobel gases - -group 0 are very unreactive as they have an empty outer shell What is metallic bonding? - -It involves a lattice of ions surrounded by a sea of delocalized electrons. Why are metals good conductors of electricity and heat ? - -Metals are good conductors of electricity because of the free movement of delocalized electrons. ionic bonding - -between metals and non metals metal atoms donate electrons to non metals to form ions What is the structure of ionic compounds? - -Ions are arranged in a lattice of repeating positive and negative ions to form a crystal. Why do ionic substances have high melting and boiling points? - -Due to the strong ionic bonds present in the lattice structure. In what states can ionic compounds conduct electricity? - -When molten or in solution, as the ions are free to move and carry a charge. What are positive ions called? - -Cations. What are negative ions called? - -Anions. What is another name for ionic compounds? - -Salts. What are molecules - -two or more atoms bonded together What are compounds - -substances in which atoms of two or more elements are chemically combined CHEMISTRY Hydroxide ion - -OH- sulphate ion - -SO4 2- Carbonate ion - -CO3 2- Nitrate ion - -NO3- Ammonium ion - -NH4+ What is covalent bonding? - -Non-metal bonding where atoms share electrons to form full outer shells. What does every covalent bond consist of? - -A pair of shared electrons. Why do simple covalent structures have low boiling points? - -Due to weak intermolecular forces that need to be overcome. What is giant covalent bonding? - -A structure consisting of repeating units of atoms to form giant molecules with high melting points due to the need to break covalent bonds. What makes diamond very strong? - -Its structure with giant covalent bonding. What is graphite? - -An allotrope of carbon with layers of carbons having 3 bonds in a hexagonal structure, with delocalized electrons forming weak bonds between layers. Why can graphite conduct electricity? - -Due to the presence of delocalized electrons that can move within the structure. What is graphene? - -A single layer of graphite, known for its unique properties. What are alloys? - -Mixtures of metals. How do different size atoms affect alloys? - -They disrupt the lattice, making layers unable to slide over each other easily, resulting in increased strength. What are fullerenes used for? - -Electronics, composites, and medical purposes How many carbon atoms make up a buckminster fullerene? - -60 What size range do nano particles fall into? - -1-100 nm What is the size range for fine particles? - -100-2500 um Why are fullerenes used in various applications? - -Due to their high surface area to volume ratio