Vocabulary Basics
The substances that start a chemical reaction.
What are reactants?
This scientific law says matter cannot be created or destroyed.
What is the Law of Conservation of Mass?
A + B → AB
What is synthesis?
This evidence is seen when bubbles form.
What is gas production?
In the equation H₂ + O₂ → H₂O, which side are the products on?
What is the right side?
The substances formed during a chemical reaction.
What are products?
In a chemical reaction, atoms are not destroyed — they do this instead.
What is rearrange?
AB → A + B
What is decomposition?
This evidence happens when a solid forms in a liquid.
What is a precipitate?
In the equation 3CO₂, what does the “3” represent?
The coefficient (number of molecules).
A written way to show a chemical reaction using formulas and symbols,
What is a chemical equation?
Why do chemical equations need to be balanced?
To show the same number of atoms on both sides.
A + BC → AC + B
What is single replacement?
This evidence occurs when the temperature increases or decreases.
What is a temperature change?
In the formula H₂O, what does the “2” represent?
The subscript (number of hydrogen atoms in one molecule).
A large number placed in front of a chemical formula to show the number of molecules.
What is a coefficient?
If an equation is not balanced, this law is being violated.
What is the Law of Conservation of Mass?
AB + CD → AD + CB
What is double replacement?
This evidence happens when light is given off.
What is light production?
What reaction type usually requires oxygen and releases energy?
What is combustion?
A small number written after an element symbol that shows how many atoms are in one molecule.
What is a subscript?
Changing these adjusts the number of molecules without changing the substance.
What are coefficients?
A substance reacts with oxygen to release energy, usually producing CO₂ + H₂O.
What is combustion?
The mnemonic “City Girls Only Like Their Phones” helps you remember what?
What is the evidence of a chemical reaction?
Explain why changing a subscript is not allowed in a chemical equation.
It changes the substance itself, not the amount.