Unit 4 Lesson 1 Flashcards
Chemical Reaction
The process in which atoms are rearranged to produce new substances with different properties
Bonds between atoms are formed or broken
Color change, change in odor, precipitate, gas bubbles are evidence of chemical reaction
Chemical Formula
Subscripts
Coefficients
Uses chemical symbols and numbers to represent at substance
The numbers written below and to the right of the symbol. Tell how many of each type of atom is in a molecule
A number placed in front of a chemical formula. Tells you how many of that molecule you have
Chemical Equation
An expression that uses symbols to show the relationship between the starting substance and the substances produced in a chemical reaction
Reactants
Products
The substances that participate in a chemical reaction ( on the left)
The substances formed in the reaction ( on the right)
Law of conservation of Mass
Matter is not created or destroyed in reactions so there must be the same # and kinds of atoms on both sides of the chemical equation
Endothermic Reaction
A reaction that requires an input of energy from the surroundings like heat
Example: Photosynthesis
The products are higher in energy and often feel cold
Exothermic reaction
A chemical reaction where energy is released or given off
Example: burning
The products are lower in energy and often feel warm
Law of Conservation of Energy
Energy is not created or destroyed but can change form
The total amount of energy in endothermic or exothermic reactions doesn’t change
What affects the rates of reactions?
Concentration - increasing concentration increasesreaction rate
Surface area - increasing surface area increases rate
Temperature - increasing temperature increases reaction rate
Catalyst - a substance that changes the rate of a chemical reaction without being used up or changed much
