Matter and Conservatoin
According to the Law of Conservation of Mass, what happens to the total mass of substances during a chemical reaction?
The total mass remains the same; mass is conserved.
How many valence electrons does oxygen have?
A. 2 B. 4 C. 6 D. 8
6
Why must chemical equations be balanced?
A. To make the reaction look nicer
B. To follow the Law of Conservation of Mass
C. To make the reaction faster
D. To remove atoms
B
What are polymers?
A. Small atoms floating alone
B. Large molecules made of repeating smaller units
C. A type of metal
D. A type of gas
B. Large molecules made of repeating smaller units
True or False: Mass can be created during a chemical reaction.
False
True or False: Valence electrons are the electrons in the innermost energy level of an atom.
False
True or False: The number of atoms must be the same on both sides of a balanced equation.
True
True or False: Many everyday materials like plastics and rubber are polymers.
True
Explain in one sentence why chemical equations must be balanced.
Because atoms are conserved; balancing ensures same number of each atom on both sides.
Define valence electrons and explain why they matter in chemical reactions.
Valence electrons are the electrons in the outermost energy level that participate in bonding; they determine how atoms bond (ionic/covalent).
Balance the equation N2+H2→ NH3
N2+3H2→2NH3
What is a polymer?
Polymer = large molecule of repeating units (monomers)
Balance the equation H2+O2→H2O
2H2+O2→2H2O.
How many valence electrons does Nitrogen (N) have?
5
Balance the equation Na+Cl2→NaCl
2Na+Cl2→2NaCl
What is a monomer?
small subunit/building block that makes up a polymer
A sealed container holds reactants that react to form products. Describe what happens to the total number of atoms and the measured mass inside the sealed container, and explain why.
Total number of atoms and mass remain the same; mass is conserved because atoms are rearranged, not created/destroyed.
How many valence electrons is the "golden number" that all elements are trying to get to/achieve when they make chemical bonds.
8
Balance the equation Fe+O2→Fe2O3
4Fe+3O2→2Fe2O3
What is a cross linking polymer?
Think of linear polymers as individual strings of spaghetti and cross-linked polymers as a knotted net