Science - Term 2 Flashcards
(37 cards)
Atom
The smallest particle of an element that has all of the chemical properties of that element. Atom consists of a nucleus (containing protons and neutrons) surrounded by electrons
Element
Any of the more than 100 known substances that cannot be separated into simpler substances and that singly or in combination constitute that matter
Molecule
Two or more atoms that are joined by a chemical bond. Smallest group of atoms that can composition.
Compound
A chemical substance formed from two or more elements, with a fixed ratio determining the composition
Reactant
Substance that is a starting material before a chemical change
Product
A chemical substance formed as a result of a chemical reaction
Acidic
A substance which contains hydrogen and dissolves in water to produce one or more hydrogen ions. Acidity is commonly measured using the pH scale. Acids have a pH lower than 7
Alkaline
A base that is soluble in water
Base
A substance that has a pH greater than 7 and has hydroxide or carbonate as part of their name. A base that dissolves in water is said to be alkaline
Chemical reaction
A process involving one, two or more substances (called reactants), characterised by a chemical change and yielding one or more product(s) which are different from the reactants
Indicator
A chemical that changes colour when exposed to certain conditions and is therefore useful for chemical tests e.g. litmus paper
Chemical formula
A set of chemical symbols showing the elements present in a compound and how many there are for each element in the form of subscripts
Catalyst
A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change
Endothermic
Reactions in which heat energy is absorbed from the surroundings due to the reaction
Enzyme
A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction. Usually a protein.
Exothermic
Reactions in which heat energy is released from the reaction to the surroundings
Rate
The speed at which something happens
Surface area
The measure of how much exposed area a solid object has, usually expressed in square units such as metres squared or square centimetres
Temperature
A measurement of the warmth or coldness of an object. It is measured in degrees celsius and usually using a thermometer.
Chemical energy
Energy stored in the chemical bonds between atoms in a molecule. It can be released when chemicals break apart or absorbed when they are joined
Biotechnology
Any technological application that uses biological systems, living organisms, or derivatives thereof; to make or modify products or processes for specific use
Characteristic
Feature defined by a standard of points or identified features
Chromosome
A thread-like structure found in the nucleus of all cells where DNA is packaged up in sections to protect it
DNA
Deoxyribonucleic acid; the chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms
