CHEMISTRY VOCABULARY -- Formulas, Equations, and the Conservation of Mass
SYMBOLS -- one or two letter used to represent an element.
CHEMICAL FORMULA -- a combination of symbols and numbers that represent the number and types of elements (atoms) present in a compound.
Example: Water is a compound of Hydrogen (H) and Oxygen (O) that uses the chemical formula H2O.
SUBSCRIPT – a small number to the right of a symbol that is written below the normal line of the letters to show how many atoms of an element are present in a substance. No subscript means there is only one atom present.
CHEMICAL REACTION – When substances interact to form one or more new substances with different properties than the original substances.
CHEMICAL EQUATION – a combination of chemical formulas used to describe what happens in a chemical reaction. The equation identifies the reactants and resulting products.
EXAMPLE: 2H + O à H2O
COEFFICIENT – a number written in front of a chemical formula to show how many molecules of that substance are present.
REACTANT – Formulas written on the left side of the arrow symbol ( à) are the starting substances in a chemical reaction.
PRODUCT – Formulas written on the right side of the arrow symbol (à) are the NEW SUBSTANCES that are formed (or PRODUCED) in a chemical reaction.
YEILDS – an arrow symbol that shows a reaction has taken place. The reactants have reacted to produce a new substance (the product).
COMPOUND – a substance composed of two or more elements chemically combined and in a definite proportion.
PHYSICAL CHANGE – a change in which the characteristics of a substance are only changed physically and the original properties stay the same.
CHEMICAL CHANGE – a change in which a substance (or substances) is changed into one or more new substances with different properties than the original substances. LAW OF CONSERVATION OF MASS – Matter is not created or destroyed, only changed. The number of atoms in the reactants must be equal to the number of atoms in the product.
PRECIPITATE – A solid that forms as a result of a chemical reaction. It will fall to the bottom of the container.