Chemical Reactions

Performance Expectations MS-PS1-5. I can explain the conservation of mass through a model of chemical reactions. MS-PS1-3 I can gather information to describe the origins and impacts of synthetic material

What is a chemical reaction? When elements and/or compounds interact to form new compounds A new substance is made during a chemical reaction

2 H2 + O2  2 H2O Chemical Equations We use chemical equations to represent the chemical reaction with chemical formulas and numbers. 2 H2 + O2  2 H2O This is the chemical equation showing how hydrogen and oxygen react to make water

Parts of a Chemical Equation Reactants and Products Chemical reactions are read left to right. The starting substances are called the reactants The substance that is made as a result of the chemical reaction are called products 2 H2 + O2  2 H2O Reactants Products

Parts of a Chemical Equation Chemical Formulas A chemical formula is a why to represent a substance. Atomic Symbols- from the periodic table to represent the types of atoms in the substance Subscripts- tell the number of each type of atom in a molecule 2 H2 + O2  2 H2O H2 is the chemical formula for a hydrogen molecule. H2O is the chemical formula for a water molecule

Parts of a Chemical Equation Coefficients Coefficients tell us the proportions that the molecules need to react in. They show how matter is conserved 2 H2 + O2  2 H2O The coefficient of 2 shows us that two molecules of hydrogen need to react for every 1 molecule of oxygen Not having coefficient is the same as saying 1

How Do I know a Chemical Reaction Happened You may not be able to see the molecules but there are some signs that a reaction has occurred Color Change Creation of a New Gas Change in Temperature Smell Light

Vocabulary Pt II.

Chemical formula A representation of a substance in which the elements are represented by their symbols and subscripts represent the number of atoms of each element H2O

Chemical change The formation of a new substance with different properties; cannot be undone by physical means

2 H2 + O2  2 H2O Chemical equation A representation of a chemical reaction by symbols and numbers 2 H2 + O2  2 H2O

Law of conservation of mass Matter is not created or destroyed; only rearranged

Product Substance(s) resulting from a chemical reaction

Reactant Substances that are combined and changed during a chemical reaction

Element A substance made of only one kind of atom.

Synthetic Made by human means and not originally found in nature.