20 terms

Unit 3: Chemical Reactions

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Substance
Matter that has the same composition and properties throughout; contains only one element or molecule
Molecule
Two or more atoms that are bonded together (can be 2 of the same element or 2 different elements)
Chemical Formula
Identifies the number of atoms of each element in a molecule
Subscript
The small number following the symbol of an element that shows how many atoms of that element are in the molecule (no # means there is 1 atom)
Chemical Bond
An interaction between atoms where electrons are shared to form molecules
Mixture
Matter which contains more than one substance
Solution
A mixture that forms when one substance dissolves another; solid, liquid, or gas that looks as if it could be one substance
Physical State
The condition in which matter may be found: solid, liquid, or gas
Physical Change
A change in matter that only affects the appearance of the substance
Chemical Change
A change in matter which results in a new and different substance being formed
Dissolve
A physical change in which a solid is mixed in with a liquid
Chemical Reaction
When atoms of at least two different substance rearrange to form new and different substances
Chemical Equation
Shows the formulas for the reactants and products in a chemical reaction
Coefficient
The number that comes before a chemical formula and shows how many molecules are involved in a reaction
Reactants
Substances that are present before a chemical reaction occurs
Products
Substances that are produced from a chemical reaction
Yield
The arrow symbol in a chemical equation
Endothermic
A chemical reaction that absorbs heat
Exothermic
A chemical reaction that gives off heat
Precipitate
A solid that is produced during a chemical reaction between two or more liquids

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