ALL OF PAPER 1 CHEMISTRY

• Substances are made of atoms, different types of atoms are represented in the periodic table by a symbol
• A compound is a substance containing two or more different types of atoms chemically bonded together
• Atoms change what they're bonded to and how they're bonded through chemical reactions
• A mixture is any combination of different types of elements and compounds not chemically bonded together
• Solutions are mixtures like saltwater, where a solute (solid dissolved in a liquid) can be separated by processes like filtration, crystallization, and distillation
• Solid, liquid, and gas are the three main states of matter; physical changes like melting or evaporating a substance involve supplying energy to overcome forces of attraction between particles
• Atoms are made up of protons, neutrons, and electrons; the periodic table provides information about atoms, including atomic number and mass number
• Atoms with different numbers of neutrons of the same element are called isotopes.
• The modern periodic table organizes elements based on atomic number and properties; elements are grouped into metals and non-metals
• Metals donate electrons to gain an empty outer shell, while non-metals accept electrons to gain a full outer shell; groups in the periodic table have similar properties
• Group 1 elements are alkali metals, group 7 elements are halogens, and group 0 (8) elements are noble gases with unique reactivity patterns
• Metals form positive ions by losing electrons, while non-metals form negative ions by gaining electrons; transition metals can donate different numbers of electrons
• Transition metals bond through metallic bonding, forming a lattice of ions with delocalized electrons around them, making them good conductors of electricity and heat
• Metals bond to non-metals through ionic bonding, where a metal atom donates electrons to a non-metal atom to achieve stability
• Metals make good conductors of electricity and heat
• Metals bond to non-metals through ionic bonding, where a group one metal loses an electron while a group seven atom gains one
• Ionic compounds consist of repeating units of ions in a lattice, have high melting and boiling points due to strong electrostatic forces, and can conduct electricity in liquid form or when dissolved in a solution
• Non-metals bond through covalent bonding to form molecules by sharing electrons.
• Simple molecular structures have low boiling points due to weak intermolecular forces, unlike ionic compounds, they can't conduct electricity even as liquids
• Giant covalent bonding forms a giant molecule, like diamond or graphite, with strong covalent bonds throughout
• Graphite consists of layers of carbon atoms with three bonds each in a hexagonal structure, allowing it to conduct electricity and have layers that can slide over each other easily
• Metal alloys are stronger than pure metals due to different size atoms disrupting the regular lattice, making layers unable to slide over each other easily
• To calculate the number of moles of a substance, use the formula: moles = mass / relative atomic
• Reduction is the opposite of oxidation, where a reactant gains electrons
• In a reaction, reduction and oxidation occur depending on whether a reactant loses or gains electrons
• In electrolysis, positive metal ions move to the cathode where they are reduced, while negative ions move to the anode where they are oxidized
• Electrolysis can be used to purify or extract metals from compounds
• Potential energy and kinetic energy balance in reactions: if potential energy decreases, kinetic energy increases, resulting in a hotter temperature
• Activation energy is the energy needed to start a reaction.
• JJ Thomson's model


  'Plum pudding' model
• Ernest Rutherford's discovery


  • Nucleus was small and positively charged
  • Most alpha particles went straight through a gold leaf, very few deflected back
• Niels Bohr's deduction


  Electrons exist in 'shells'
• James Chadwick's determination


  Nucleus must contain neutrons as well as protons