| Word | Definition | Topic |
|---|---|---|
| acid | A corrosive substance which has a pH lower than 7. Acidity is caused by a high concentration of hydrogen ions. | Chemical reactions |
| acids | Corrosive substances which have a pH lower than 7. Acidity is caused by a high concentration of hydrogen ions. | Chemical reactions |
| activation energy | The minimum energy required for a collision between particles, in order for a reaction to occur. | Chemical reactions |
| alkali | A base which is soluble in water. | Chemical reactions |
| alkalis | Bases which are soluble in water. | Chemical reactions |
| alkenes | Alkenes are unsaturated hydrocarbons with a double bond between the carbon atoms. | Chemical reactions |
| atom | All elements are made of atoms. An atom consists of a nucleus containing protons and neutrons, surrounded by electrons. | Chemical reactions |
| base | A substance with a pH higher than 7, and which has a high concentration of hydroxyl ions. Bases react with acids to form a salt and water (called neutralisation). Metal hydroxides, oxides and carbonates are all bases. | Chemical reactions |
| bases | Substances with a pH higher than 7, and which have a high concentration of hydroxyl ions. Bases react with acids to form a salt and water (called neutralisation). Metal hydroxides, oxides and carbonates are all bases. | Chemical reactions |
| biocatalyst | A biocatalyst is an enzyme or microorganism that activates or speeds up a biochemical reaction. | Chemical reactions |
| catalyse | To catalyse a chemical reaction is to change the rate of reaction (without the catalyst substance itself being changed by the reaction). | Chemical reactions |
| catalyst | A catalyst changes the rate of a chemical reaction without being changed by the reaction itself. | Chemical reactions |
| catalyst | A catalyst changes the rate of a chemical reaction without being changed by the reaction itself. | Chemical reactions |
| chemical change | A chemical change involves new substances being formed and is very difficult to reverse. | Chemical reactions |
| combustion | Combustion is the process of burning by fire. | Chemical reactions |
| compound | A compound is a substance formed by the chemical union (involving bond formation) of two or more elements. | Chemical reactions |
| concentration | 2 | Chemical reactions |
| covalent compounds | A covalent compound is a compound of neutral atoms in which the atoms are held together by covalent bonds. Covalent bonds between atoms form when atoms share electrons to achieve a full outer shell of electrons. | Chemical reactions |
| denatured | If a protein is denatured, its structure and function is altered. This can be caused by heat, altered pH or by chemical agents. | Chemical reactions |
| displace | Displacement reactions happen when a more-reactive element replaces a less-reactive element in a compound. | Chemical reactions |
| displacement | Displacement reactions happen when a more-reactive element replaces a less-reactive element in a compound. | Chemical reactions |
| displacement reaction | Displacement reactions happen when a more-reactive element replaces a less-reactive element in a compound. | Chemical reactions |
| electrode | Electrodes are conductors used to establish electrical contact with a circuit. The electrode attached to the negative terminal of a battery is called a negative electrode, or cathode. The electrode attached to the positive terminal of a battery is the positive electrode, or anode. | Chemical reactions |
| electrolysis | Electrolysis is the decomposition (separation or break-down) of a compound using an electric current. | Chemical reactions |
| electron | An electron is a very small negatively-charged particle found in an atom in the space surrounding the nucleus. | Chemical reactions |
| endothermic | In an endothermic reaction, energy is taken in from the surroundings. The surroundings then have less energy than they started with, so the temperature falls. | Chemical reactions |
| equilibrium | If the rate of the forward reaction and the rate of the back reaction in a reversible reaction are equal, the reaction is in equilibrium. | Chemical reactions |
| evaporation | Evaporation is a change in state in which a liquid becomes a gas (vapour); molecules near the surface of a liquid may leave the liquid to become a vapour. | Chemical reactions |
| exothermic | Heat energy is released in an exothermic reaction. We know this because the surroundings get warm. | Chemical reactions |
| filtrate | Filtrate is fluid that has passed through a filter. | Chemical reactions |
| filtration | Filtration is used to separate a solid from a liquid. | Chemical reactions |
| ionic compound | An ionic compound occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron). The ions swap electrons to achieve a full outer shell. | Chemical reactions |
| molecule | A molecule is a collection of two or more atoms held together by chemical bonds. It is the smallest part of a substance that displays the properties of the substance. | Chemical reactions |
| neutralisation | Neutralisation is the reaction between an acid and a base. | Chemical reactions |
| oxidation | Oxidation is a reaction in which oxygen combines with a substance. Oxidation also means a loss of electrons. | Chemical reactions |
| product | A product is a substance formed in a chemical reaction. | Chemical reactions |
| reactant | A reactant is a substance put together with another substance/substances to undergo a chemical reaction. | Chemical reactions |
| redox reaction | Oxidation and reduction always take place together. The combined reaction is called a redox reaction. | Chemical reactions |
| reduction | Reduction is a reaction in which oxygen is removed from a substance. Reduction also means a gain in electrons. | Chemical reactions |
| reversible reactions | Reversible reactions are chemical reactions which can go both ways. The direction of the reaction depends on the condition of the reactants. | Chemical reactions |
| salt | A compound formed by neutralisation of an acid by a base (eg a metal oxide) - the result of hydrogen atoms in the acid being replaced by metal atoms or positive ions. Sodium chloride - common salt - is one such compound. | Chemical reactions |
| salts | Compounds formed by neutralisation of an acid by a base (eg a metal oxide) - the result of hydrogen atoms in the acid being replaced by metal atoms or positive ions. Sodium chloride - common salt - is one such compound. | Chemical reactions |
| solute | A solute is the material that dissolves in a solvent to form a solution. | Chemical reactions |
| solution | A solution is the mixture formed when a solute dissolves in a solvent. | Chemical reactions |
| solvent | A solvent is the liquid in which the solute dissolves to form a solution. | Chemical reactions |
| substrate | A substrate is the substance acted upon by an enzyme. | Chemical reactions |
| thermal decomposition | A reaction in which substances are broken down by heat. | Chemical reactions |
