“Counting Atoms in a Chemical Equation” Notes
Chemical Bond- the force that holds atoms together
Chemical reaction- occurs when chemical bonds are either formed or
broken apart
Chemical Change- a change in matter that produces a new substance
Chemical symbol- one or two letters given to represent an element. The
first letter is always capitalized and the second letter is always lower case.
Chemical formula- combination of chemical symbols and number to
represent a substance
Subscript- # written below and to the right of a chemical symbol
indicating the number of atoms of that element. If there is no subscriptthere is only ONE atom. Subscripts are never changed when balancing
equations.
Types of chemical reactions:
Synthesis- 2 or more elements or compounds combine to form one substance
Example:
2H2 + O22H2O
Decomposition- 1 substance is broken down into 2 or more substances
Example:
2HgO 2Hg + O2
Replacement- one or more elements or compounds in a reaction replaces another
Example:
Cu + 2AgNO3Cu(NO3)2 + 2Ag
Chemical equation- uses chemical symbols and formulas as a shortcut to
describe a chemical reaction. At the end of a reaction, the same atoms
exist, but they are grouped together as different molecules
Reactants- starting material in a chemical reaction. On the left side of an
equation.
Products- substance formed from a reaction. On the right side of an
equation.
Is stated as “yields”
Coefficient- number placed in front of a chemical symbol or formula to
indicate number of molecules
Law of Conservation of Mass- “Matter is neither created nor destroyed”
The total mass of the reactants equals the total mass of the products.
“Counting Atoms in a Chemical Equation” Notes
Name: _________________
Chemical _____________- the force that holds atoms together
Chemical _____________- occurs when chemical bonds are either
formed or broken apart
Chemical _________- a change in matter that produces a new substance
Chemical ______- one or two letters given to represent an element. The
first letter is always capitalized and the second letter is always lower case.
Chemical ___________- combination of chemical symbols and number
to represent a substance
_______- # written below and to the right of a chemical symbol indicating
the number of atoms of that element. If there is no subscript- there is only
ONE atom. Subscripts are never changed when balancing equations.
Types of chemical reactions:
Synthesis- 2 or more elements or compounds _____________ to form _______substance
Example:
2H2 + O22H2O
Decomposition- 1 substance is __________ ____________ into 2 or more substances
Example:
2HgO 2Hg + O2
Replacement- one or more elements or compounds in a reaction _______________ another
Example:
Cu + 2AgNO3Cu(NO3)2 + 2Ag
Chemical ____________- uses chemical symbols and formulas as a
shortcut to describe a chemical reaction. At the end of a reaction, the
same atoms exist, but they are grouped together as different molecules
_____________- starting material in a chemical reaction. On the left
side of an equation.
_____________- substance formed from a reaction. On the right side of
an equation.
Is stated as “yields”
Coefficient- number placed in ___________ of a chemical symbol or
formula to indicate number of __________________
Law of Conservation of Mass- “Matter is neither ___________ nor
____________” The total mass of the reactants equals the total mass of
the products.