Science term 1

• Exothermic reactions release energy, while endothermic reactions absorb energy.
• A chemical change is when two or more substances form a new substance with a different atomic structure
• Chemical changes are often accompanied by physical changes such as the formation of gas bubbles, colour changes, and temperature changes.
• Combustion is a chemical reaction that is caused by combining a fuel and oxygen, resulting in the products of carbon dioxide, water and energy
• During combustion, the energy released as a product is often in the form of heat
• During a chemical reaction, the breaking of chemical bonds uses the surrounding energy and the forming of new chemical bonds releases energy
• An exothermic reaction is when the amount of energy released is greater than the amount of energy absorbed
• An endothermic reaction is when the amount of energy absorbed is greater than the amount of energy released
• Acid and metal when combined in a chemical reaction produces salt and hydrogen gas
• The purpose of a controlled variable is to ensure that the independent variable is the only factor that affects the dependent variable