When an element exists as a diatomic molecule, the element symbol is followed by the subscript ___.
2
Element symbols represent ___.
Elements
When chemical formulas differ, they represent different ___.
Substances
A ___ is a description of a reaction using element symbols and chemical formulas.
Chemical equation
Is this equation balanced?
No
Sometimes, changes in ___ properties, such as color or odor, indicate a chemical reaction.
Physical
The only way to be certain a chemical reaction has taken place is to compare the chemical properties of the substances ___ the change
Before and after
A ___ change does not produce new substances.
Physical
___ are the starting substances in a chemical reaction.
Reactants
A chemical equation includes the substances that ___ and the substances ___.
React, formed
___ is absorbed or released during a chemical reaction and is evidenced by warming or cooling.
Thermal energy
Is this equation balanced?
No
A chemical formula contains ___ and ___ to describe the makeup of a compound.
Element symbols and subscripts
A solid formed when two liquids are mixed is called a ___ and can be evidence of a chemical reaction.
Precipitate
A chemical reaction is a process in which atoms of one or more substances rearrange to form one or more new ___.
Substances
Two or more reactants are separated by ___ signs, as are any two or more products.
Plus
A change in energy is another sign that a ___ has occurred.
Chemical reaction
___ are the substances produced by a chemical reaction.
Products
The starting substances and the substances produced have different physical and chemical ___.
Properties
Mass is conserved in a chemical reaction because ___ are conserved.
Atoms
During a chemical reaction, atoms of elements or compounds ___ and form new elements or compounds.
Rearrange
Is this equation balanced?
Yes
To show that mass is conserved, a chemical equation must show that the number of each type of atom must be ___, or the same on both sides of the equation.
Balanced
The ___ states that the total mass of the reactants before a chemical reaction is the same as the total mass of the products after the chemical reaction.
Law of conservation of mass
Atoms rearrange when chemical ___ between atoms break.
Bonds
True or False: In a chemical equation, the reactants are written to the left of an arrow, and the products are written to the right of the arrow.
True
Chemical equations are balanced by adding ___.
Coefficients
Chemical formulas represent ___.
Compounds
During a ___ change, new substances form.
Chemical
A ___ is a number placed in front of an element symbol or a chemical formula in an equation.
Coefficient