Term | Definition |
Activation Energy: | What is needed to start a chemical reaction |
Arrow ( → ): | you read the arrow as “yields” in a chemical equation or formula |
Characteristics of a Chemical Reaction: | changes in energy or changes in properties (produce a gas (bubbles form), color change, precipitate forms or temperature change) |
Chemical Changes: | alter the chemical properties of matter; new substances with new properties are formed. |
Chemical Equations: | a shorter, easier way to show chemical reactions by using symbols instead of words |
Coefficient: | a number placed in front of a chemical formula in an equation. Tells how many atoms or molecules of each reactant and product take part in the reaction. |
Conservation of Mass: | the amount of matter involved in a chemical reaction does not change. The total mass of the reactants must equal the total mass of the products |
Controlling rates of reaction: | |
Concentration (amount of one material in a given amount of another material) | |
Temperature (higher heat causes faster reactions) | |
Surface Area (increased surface area = increased reaction) | |
Catalysts (materials that increases the rate of reaction) | |
Enzymes (biological catalysts) | |
Inhibitors (decreases the rate of a reaction) | |
Decomposition Reaction: | a compound breaks down into simpler substances |
Endothermic Reaction: | an observable change in energy that shows a chemical reaction took place; A reaction that takes heat from the solution, absorbs energy, makes it feel cooler |
Exothermic Reaction: | an observable change in energy that shows a chemical reaction took place; a reaction that releases heat; gives off energy, makes it feel warmer; most chemical reactions are this type. |
Physical Changes: | alter only the physical properties of matter; no new substances are formed. Can be a change in size, shape or color; change in phase (by increasing or decreasing temperature: solid, liquid, gas) |
Precipitate: | a solid that forms from solution during a chemical reaction; observable change that shows a chemical reaction took place |
Products | he mat: terials you have after a chemical reaction; written on the right side of the formula |
Reactants: | the materials you have at the beginning of a chemical reaction; written on the left side of the formula |
Replacement Reaction: | one part of a compound is displaced by an element or compound from another substance (also called displacement reaction) |
States of Matter (pp. 46-50): | solid, liquid, and gas |
Subscripts: | show the number of atoms of an element in a molecule or the ratio of elements in a compound. |
Synthesis Reaction: | two substances combine to form a new compound (also called composition reaction) |