Oxford AQA Chemistry 7405 - Cambridge Classroom

Fundamental Concepts & States of Matter • Atom: The smallest particle of an element that can exist, made of a nucleus (protons and neutrons) and electrons orbiting it. • Element: A pure substance consisting of only one type of atom, which cannot be broken down into simpler substances by chemical means. • Compound: A substance formed when two or more different elements are chemically bonded together in a fixed ratio. • Mixture: A substance containing two or more elements or compounds not chemically bonded together. Can be separated by physical means. • Molecule: A group of two or more atoms held together by chemical bonds. • Proton: A subatomic particle found in the nucleus with a relative mass of 1 and a charge of +1. • Neutron: A subatomic particle found in the nucleus with a relative mass of 1 and no charge (0). • Electron: A subatomic particle orbiting the nucleus with a negligible relative mass and a charge of -1. • Atomic Number (Z): The number of protons in the nucleus of an atom. Defines the element. • Mass Number (A): The total number of protons and neutrons in the nucleus of an atom. • Isotopes: Atoms of the same element (same atomic number) but with different mass numbers due to a different number of neutrons. • Relative Atomic Mass ($A_r$): The weighted average mass of an atom of an element compared to $1/12$th the mass of a carbon-12 atom. • Relative Molecular Mass ($M_r$): The sum of the relative atomic masses of all atoms in one molecule of a compound. • Relative Formula Mass ($M_r$): The sum of the relative atomic masses of all atoms in the formula unit of an ionic compound. • Mole: The amount of substance that contains $6.02 \times 10^{23}$ particles (Avogadro's number). • Molar Mass: The mass of one mole of a substance, expressed in g/mol. Numerically equal to $A_r$ or $M_r$. • Empirical Formula: The simplest whole number ratio of atoms of each element in a compound. • Molecular Formula: The actual number of atoms of each element in a molecule. • Solid: Particles are closely packed in a fixed, regular arrangement, vibrate about fixed positions. Definite shape and volume. • Liquid: Particles are closely packed but randomly arranged, can slide past each other. Definite volume, no definite shape. • Gas: Particles are far apart and arranged randomly, move rapidly and randomly. No definite shape or volume. • Melting Point: The specific temperature at which a solid changes into a liquid at a given pressure. • Boiling Point: The specific temperature at which a liquid changes into a gas (vaporizes) at a given pressure. • Sublimation: The direct change of state from solid to gas without passing through the liquid phase (e.g., solid $\text{CO}_2$). • Diffusion: The net movement of particles from a region of higher concentration to a region of lower concentration, due to random motion. • Osmosis: The net movement of water molecules across a partially permeable membrane from a region of higher water potential to a region of lower water potential. 2. Structure & Bonding • Ionic Bond: The electrostatic force of attraction between oppositely charged ions, formed by the transfer of electrons from a metal to a non-metal. • Covalent Bond: A strong electrostatic force of attraction between a shared pair of electrons and the nuclei of the bonded atoms, typically between two non-metals. • Metallic Bond: The electrostatic force of attraction between positive metal ions and delocalised electrons. • Ion: An atom or group of atoms that has gained or lost electrons, resulting in a net electrical charge. • Cation: A positively charged ion (lost electrons). • Anion: A negatively charged ion (gained electrons). • Octet Rule: Atoms tend to gain, lose, or share electrons in order to achieve a full outer electron shell, typically with eight electrons. • Giant Ionic Lattice: A regular, repeating 3D arrangement of oppositely charged ions, held together by strong electrostatic forces. • Simple Molecular Structure: Molecules held together by strong covalent bonds, but with weak intermolecular forces between molecules. • Giant Covalent Structure (Macromolecular): A large structure where all atoms are held together by strong covalent bonds in a continuous network (e.g., diamond, silicon dioxide). • Allotropes: Different structural forms of the same element in the same physical state (e.g., diamond and graphite are allotropes of carbon). • Electronegativity: The power of an atom to attract the electron pair in a covalent bond to itself. • Polar Covalent Bond: A covalent bond in which electrons are shared unequally due to a difference in electronegativity between the bonded atoms. • Hydrogen Bond: A strong type of intermolecular force that occurs between molecules containing hydrogen bonded to a highly electronegative atom (N, O, F). • Van der Waals' forces: Weak intermolecular forces of attraction between all molecules, arising from temporary dipoles. 3. Stoichiometry & Chemical Calculations • Stoichiometry: The study of quantitative relationships between reactants and products in chemical reactions. • Limiting Reactant: The reactant that is completely consumed in a chemical reaction, determining the maximum amount of product that can be formed. • Excess Reactant: The reactant present in a greater amount than required to react with the limiting reactant. • Yield: The amount of product obtained from a chemical reaction. • Theoretical Yield: The maximum amount of product that can be formed from a given amount of reactants, calculated using stoichiometry. • Actual Yield: The amount of product actually obtained from a chemical reaction, usually less than the theoretical yield. • Percentage Yield: $($Actual Yield $/$ Theoretical Yield$) \times 100\%$. • Concentration: The amount of solute dissolved in a given volume of solvent or solution. Often expressed in mol/dm$^3$ (molarity) or g/dm$^3$. • Solute: The substance that dissolves in a solvent to form a solution. • Solvent: The substance in which a solute dissolves to form a solution. • Solution: A homogeneous mixture formed when a solute dissolves in a solvent. 4. Chemical Reactions & Energetics • Chemical Reaction: A process that involves rearrangement of the atomic structure of substances, resulting in the formation of new substances. • Reactants: The starting substances in a chemical reaction. • Products: The substances formed as a result of a chemical reaction. • Word Equation: An equation that uses the names of the reactants and products. • Symbol Equation: An equation that uses chemical symbols and formulae to represent reactants and products, and is balanced. • Balancing Equation: Ensuring the number of atoms of each element is the same on both sides of a chemical equation. • Redox Reaction: A reaction involving both reduction and oxidation. • Oxidation: Loss of electrons, gain of oxygen, or loss of hydrogen. Increase in oxidation state. • Reduction: Gain of electrons, loss of oxygen, or gain of hydrogen. Decrease in oxidation state. • Oxidising Agent: A substance that causes oxidation by accepting electrons (and is itself reduced). • Reducing Agent: A substance that causes reduction by donating electrons (and is itself oxidised). • Exothermic Reaction: A reaction that releases energy to the surroundings, usually as heat, causing the temperature of the surroundings to rise. $\Delta H$ is negative. • Endothermic Reaction: A reaction that absorbs energy from the surroundings, usually as heat, causing the temperature of the surroundings to fall. $\Delta H$ is positive. • Activation Energy ($E_a$): The minimum amount of energy required for reactants to collide effectively and initiate a chemical reaction. • Catalyst: A substance that increases the rate of a chemical reaction without being chemically changed itself, by providing an alternative reaction pathway with a lower activation energy. • Enthalpy Change ($\Delta H$): The heat energy change measured at constant pressure for a reaction. • Standard Enthalpy of Formation ($\Delta H_f^\circ$): The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions. • Standard Enthalpy of Combustion ($\Delta H_c^\circ$): The enthalpy change when one mole of a substance is completely combusted in oxygen under standard conditions. • Hess's Law: The total enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same. 5. Rates of Reaction & Equilibrium • Rate of Reaction: The change in concentration of a reactant or product per unit time. • Collision Theory: For a reaction to occur, reactant particles must collide with sufficient energy (activation energy) and correct orientation. • Factors Affecting Rate: Concentration, pressure (for gases), surface area, temperature, and presence of a catalyst. • Reversible Reaction: A reaction where products can react to reform the original reactants, indicated by $\rightleftharpoons$. • Chemical Equilibrium: A state in a reversible reaction where the rate of the forward reaction is equal to the rate of the reverse reaction, and the concentrations of reactants and products remain constant. • Le Chatelier's Principle: If a change in conditions (temperature, pressure, concentration) is applied to a system at equilibrium, the system will shift in a direction that counteracts the change. 6. Acids, Bases & Salts • Acid: A substance that produces hydrogen ions ($H^+$) when dissolved in water (Arrhenius definition) or a proton donor (Brønsted-Lowry definition). • Base: A substance that produces hydroxide ions ($OH^-$) when dissolved in water (Arrhenius definition) or a proton acceptor (Brønsted-Lowry definition). • Alkali: A soluble base that dissolves in water to produce hydroxide ions ($OH^-$). • Salt: A compound formed when the hydrogen ion of an acid is replaced by a metal ion or an ammonium ion. • Neutralisation: The reaction between an acid and a base (or alkali) to form a salt and water. $H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$. • pH: A measure of the acidity or alkalinity of a solution, defined as $-\log_{10}[H^+]$. Scale from 0 to 14. • Strong Acid: An acid that fully dissociates (ionizes) in water (e.g., HCl, $H_2SO_4$). • Weak Acid: An acid that partially dissociates (ionizes) in water (e.g., $CH_3COOH$). • Strong Base: A base that fully dissociates in water (e.g., NaOH, KOH). • Weak Base: A base that partially dissociates in water (e.g., $NH_3$). • Amphoteric: A substance that can act as both an acid and a base (e.g., aluminium oxide, water). • Titration: A quantitative chemical analysis method used to determine the unknown concentration of a reactant using a known concentration of another reactant. • Indicator: A substance that changes colour over a specific pH range, used to detect the endpoint of a titration. 7. Electrochemistry • Electrolysis: The decomposition of an ionic compound using electrical energy. Requires molten or aqueous electrolyte. • Electrolyte: An ionic compound (molten or dissolved in a solvent) that conducts electricity due to the movement of ions. • Electrodes: Conductors (usually metal or graphite) through which electricity enters and leaves the electrolyte. • Anode: The positive electrode, where oxidation occurs (anions are attracted). • Cathode: The negative electrode, where reduction occurs (cations are attracted). • Faraday's Laws of Electrolysis: Relate the amount of substance produced at an electrode to the quantity of electricity passed through the electrolyte. • Galvanic (Voltaic) Cell: An electrochemical cell that generates electrical energy from spontaneous redox reactions. • Standard Electrode Potential ($E^\circ$): The potential difference of a half-cell compared to a standard hydrogen electrode under standard conditions (1 M concentration, 1 atm pressure for gases, 298 K). • Electrochemical Series: A list of elements arranged in order of their standard electrode potentials, indicating their relative reactivity as oxidising or reducing agents. 8. The Periodic Table • Periodic Table: An arrangement of elements in order of increasing atomic number, showing periodic trends in properties. • Group: A vertical column in the periodic table, containing elements with the same number of valence electrons and similar chemical properties. • Period: A horizontal row in the periodic table, containing elements with the same number of electron shells. • Valence Electrons: Electrons in the outermost shell of an atom, involved in chemical bonding. • Alkali Metals (Group 1): Highly reactive metals, readily lose one electron to form $+1$ ions. React vigorously with water. • Alkaline Earth Metals (Group 2): Reactive metals, readily lose two electrons to form $+2$ ions. • Halogens (Group 17/7): Highly reactive non-metals, readily gain one electron to form $-1$ ions. Exist as diatomic molecules. • Noble Gases (Group 18/0): Unreactive elements with a full outer electron shell, existing as monatomic gases. • Transition Metals: Elements in the d-block of the periodic table, characterised by variable oxidation states, coloured compounds, and catalytic activity. • Metallic Character: Tendency of an element to lose electrons and form positive ions. Increases down a group, decreases across a period. • Non-metallic Character: Tendency of an element to gain electrons and form negative ions. Decreases down a group, increases across a period. • Ionisation Energy: The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous $1+$ ions. • Electron Affinity: The energy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of gaseous $1-$ ions. 9. Organic Chemistry • Organic Chemistry: The study of carbon compounds, excluding carbonates, carbides, and oxides of carbon. • Hydrocarbon: A compound containing only carbon and hydrogen atoms. • Saturated Hydrocarbon: A hydrocarbon containing only single carbon-carbon bonds (e.g., alkanes). • Unsaturated Hydrocarbon: A hydrocarbon containing one or more carbon-carbon double or triple bonds (e.g., alkenes, alkynes). • Homologous Series: A series of organic compounds with the same general formula, similar chemical properties, and showing a gradual change in physical properties. • Functional Group: A specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule. • Alkane: Saturated hydrocarbons with the general formula $C_nH_{2n+2}$. Contain only single bonds. • Alkene: Unsaturated hydrocarbons with the general formula $C_nH_{2n}$. Contain at least one carbon-carbon double bond. • Alkyne: Unsaturated hydrocarbons with the general formula $C_nH_{2n-2}$. Contain at least one carbon-carbon triple bond. • Alcohol: Organic compounds containing the hydroxyl functional group ($-OH$). General formula $C_nH_{2n+1}OH$. • Carboxylic Acid: Organic compounds containing the carboxyl functional group ($-COOH$). • Ester: Organic compounds formed from the reaction of a carboxylic acid and an alcohol, containing the ester linkage ($-COO-$). • Isomers: Compounds with the same molecular formula but different structural formulae. • Structural Isomers: Isomers that differ in the arrangement of their atoms or bonds. • Addition Reaction: A reaction where an unsaturated molecule adds across a double or triple bond, forming a single product. • Substitution Reaction: A reaction where an atom or group of atoms in a molecule is replaced by another atom or group of atoms. • Polymerisation: The process of joining many small monomer molecules together to form a large polymer molecule. • Monomer: A small molecule that can be joined together to form a polymer. • Polymer: A large molecule (macromolecule) formed from many repeating monomer units. • Addition Polymerisation: Polymerisation where monomers add to one another in such a way that the polymer contains all the atoms of the monomer. Usually involves unsaturated monomers. • Condensation Polymerisation: Polymerisation where monomers join together with the elimination of a small molecule (e.g., water). • Cracking: The process of breaking down long-chain hydrocarbons into shorter, more useful hydrocarbons using heat and/or a catalyst. • Fermentation: The anaerobic respiration of yeast, converting glucose into ethanol and carbon dioxide. 10. Analytical Chemistry • Qualitative Analysis: The identification of the components of a sample. • Quantitative Analysis: The determination of the amount or concentration of a component in a sample. • Chromatography: A separation technique based on differential partitioning between a stationary phase and a mobile phase. • Retention Factor ($R_f$): In paper/thin-layer chromatography, the ratio of the distance travelled by the spot to the distance travelled by the solvent front. • Spectroscopy: The study of the interaction of electromagnetic radiation with matter. • Infrared (IR) Spectroscopy: Used to identify functional groups in organic molecules based on their absorption of IR radiation. • Mass Spectrometry: Used to determine the relative molecular mass of a compound and its fragmentation pattern to deduce structure. • Flame Test: A qualitative test for the presence of certain metal ions, which produce characteristic colours when heated in a flame.

The Essential Chemistry Toolkit: Mastering Key Concepts for IGCSE, O Level, and AQA

🚀 The Essential Chemistry Toolkit: Mastering Key Concepts for IGCSE, O Level, and AQA A Premium Glossary by Prof. […]

The Essential Chemistry Toolkit: Mastering Key Concepts for IGCSE, O Level, and AQA Read More »

🚀 The Essential Toolkit Mastering Key Chemistry Concepts

Fundamental Concepts & States of Matter Atom: The smallest particle of an element that can exist, made of a nucleus

🚀 The Essential Toolkit Mastering Key Chemistry Concepts Read More »

$moles notes chemistry moles notes chemistry form 3 moles notes chemistry moles notes pdf o level chemistry moles notes intro to stoichiometry moles to moles notes igcse chemistry mole notes igcse moles notes a level chemistry moles notes gcse chemistry moles notes moles notes pdf mole concept notes a level pdf notes about moles mole with dots in middle moles with dots in them moles summary notes on mole concept moles notes chemistry mole notes pdf moleskine notes app moles and stoichiometry notes moles and molar mass notes moles and equations notes pdf moles and equations notes what is a moles purpose what are the abc's of moles what is the abcd of moles klb chemistry book 3 notes on moles moles o level notes reading moles on body notes moles and formula mass mole notes mole notes chemistry class 11 mole concept notes moles chemistry notes pdf mole concept notes pdf mole concept notes class 11 pdf mole concept notes class 11 mole concept notes pdf free download mole concept notes jee mole concept notes neet chemistry o levels moles notes moles class 11 notes chemistry form three notes on moles d#m notes mole concept notes esaral moles chemistry notes outline mole på engelsk e notes mortgage moles notes form 3 mole fraction notes mole concept notes for neet pdf mole concept notes for neet mole concept notes for jee mole concept notes form three mole concept notes for iit jee pdf mole concept notes for jee mains mole concept notes formula form 3 moles notes moles form 3 notes pdf moles form three notes mole check acronym f moles moles chemistry gcse notes moles gif intro to stoichiometry moles to grams notes what is g/mole gr a moles g/moles to grams grams to moles notes mole concept notes handwritten significance of moles moles in holes answers h moles formula h-moles formula - the natural moles notes igcse moles igcse notes pdf mole concept notes in hindi mole concept notes in hindi pdf moles in chemistry notes i mole mole concept notes jee pdf mole concept notes jee mains mole concept notes jee advanced moles joke j to moles j-notes moles beginning with k kl moles moles notes o level mole concept notes learn cbse moles chemistry o level notes moles o'levels notes l mole = moles in my signature is m moles does m mean moles does m stand for moles mole concept notes ncert n moles mole concept notes o level pdf notes on moles form 3 notes on moles notes on moles chemistry o level moles notes chemistry notes on moles form 3 chemistry notes on moles short notes on moles moles notes pmt mole concept notes pdf jee mole concept notes pdf form 3 mole concept notes pdf download mole concept notes pdf chemistry quizlet moles moles revision notes mole ratio notes mole concept notes reddit mole shapes to be concerned about moles review moles review sheet are moles in decline are moles always circular are moles raised or flat do moles serve a purpose what kind of moles should you worry about are moles normal are moles nocturnal are mortgage notes notarized are moles neoplasm moles short notes moleskine notes mole concept notes self study mole concept notes scribd suspicious moles on arm types of moles to get checked out t moles the mole notes pdf mole concept notes unacademy mole money mole problems v moles moles x molar mass how many decimal places for moles moles number mole concept notes 11th moles explained moles unit symbol 1 mole number 2 moles of no2 2 moles chemistry 2 moles of n moles chemistry form 3 notes 3 moles on chest moles you should be worried about moles i should be concerned about mole with 3 colors 3 moles chemistry 3 moles of nitrogen 3 moles = molecules 3 moles 4 moles number 4 moles chemistry 4 moles of nitrogen 4 moles in scientific notation 4 moles of naoh 5 moles 5 moles of na 5 moles of sodium 5 moles of nacl 5 moles to molecules 6 moles 6 moles of carbon 7 moles to grams moles 7 7 moles dinner 8 moles 8 moles of sodium chloride 8 moles to molecules 8 moles to grams 8 moles of oxygen 9 moles to molecules 9 moles to grams moles notes are moles normal are moles nocturnal are mortgage notes notarized are moles neoplasm can moles not be round can moles on nose be removed can moles be non cancerous can moles not have color can moles.see do moles disappear on their own do moles normally grow do moles naturally go away do moles need to be removed do moles disappear do moles normally get bigger does moles go away does moles come off does moles mean cancer does moles come and go does moles stand for molecules had mole removed now itchy had mole removed now infected had mole removed and it hurts have moles removed have lots of moles how moles work is moles number of molecules is moles cancerous is moles mass is moles molecules is moles capitalized should moles be removed should moles be killed should moles be black should moles peel should moles be hard was the mole removed from netflix what moles mean what moles are normal what moles should be removed what is a mole notes when moles should be checked when moles are concerning when moles appear out of nowhere when moles need to be checked when moles bleed where moles live where moles come from where to find moles where do moles.live which moles should be removed which moles are bad which moles are cancerous which moles to worry about which mole map is correct who removes moles who removes moles from your face why moles form why moles appear why is moles important in chemistry why use moles instead of mass will moles leave my yard will moles ever go away will moles go away will moles leave on their own will moles eventually leave your yard what moles should you worry about what should moles not look like what does moles not like moles notes notes about moles notes on mole concept significance of moles what is the history of mole mole concept notes for neet pdf mole concept notes for neet mole concept notes for jee mole concept notes for iit jee pdf mole concept notes for jee mains mole concept notes in hindi mole concept notes in hindi pdf mole with dots in middle moles with dots in them moles in my signature notes of moles notes on moles form 3 notes on moles notes on moles chemistry moles notes moles notes form 3 moles notes chemistry moles chemistry notes mole notebook moles nocturnal moles nose coles notes coles notes meaning coles notes vs cliff notes coles notes version coles notes online moles o level notes smiles notes$

The Essential Chemistry Toolkit: Mastering Key Concepts for IGCSE, O Level, and AQA

🚀 The Essential Toolkit Mastering Key Chemistry Concepts

Isotopes: Definition and Key Concepts for O Level & IGCSE Chemistry

Electronic Configuration Notes (IGCSE/O Level Chemistry 0620/5070) | A* Score

The Mole Concept and Stoichiometry – O Level/IGCSE Chemistry

The Structure of Atom – O Level Notes (Easy Explanations)

Structure of Atom O Level Notes (Easy) | 2025 Best Guides

Grade Thresholds 2025: O Level Chemistry 5070 (June/Nov) – A* Predictions & Analysis

Grade Thresholds 2025: O Level Chemistry 5070 (June/Nov) – A* Predictions

Grade Thresholds 2025: O Level Chemistry 5070 (June/Nov)

Ace Paper 4: O Level Chemistry 5070 ATP Guide & Solved

Ace Paper 4: O Level Chemistry 5070 ATP Guide & Solved

O Level Chemistry Notes PDF (All Chapters) – Complete 2026 Revision Guide

O Level Chemistry Notes PDF (All Chapters) – 2025 Syllabus | Free Download

O Level Chemistry Notes PDF (All Chapters) – Free Download 2026

IGCSE Chemistry (0620) – Complete Guide 2025 (Notes, Syllabus, Tips, Past Papers)

IGCSE Chemistry (0620) – Complete Guide 2025: Notes, Syllabus, Tips & Past Papers

IGCSE Chemistry (0620) – Complete Guide 2025 (Notes, Syllabus, Tips, Past Papers)

O Level Chemistry 5070 Best Guide: Notes, Tips & Past Papers