Chemistry

study of matter,

its properties and its behavior

formula

combination of symbols

that represent elements in a compound 

reactants

substance that enters into chemical reaction

ex. reactant + reactant = product

H + O ----->H O

coefficient

number in front of the chemical formula in an equation

tells how many moleclues or atoms of each

ex. H + O --->2H O

subscript

number in chemical formula that tells the number of atoms in a molecule

ex. H O

mixture

2 or more substances that are mixed

together but not chemically combined

ex, salad

chemical bond

force that holds two atoms together

Law of Conservation of Matter

matter cannot be created or destroyed in a chemical reaction

synthesis reaction

2 or more simple substances combine to form a new more complex substance

ex. hydrogen + oxygen = water

decomposition reaction

breaks down compounds into simpler products

ex. 2H O -->2H O + O

replacement reaction

one element replaces another ina compound

or

2 elements in different compounds trade places

ex. 2CuO +C---->2Cu + CO

endothermic reaction

absorbs energy in form of heat

exothermic reaction

releases energy in form of heat