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What you will learn from this videoWhat you will learn
- When substances undergo chemical reactions their properties change.
- The total number of atoms does not change throughout a chemical reaction.
- Scientists use chemical reactions to create new materials and medicines.
- Discussion Questions
Before Video
What is the difference between an atom and a molecule? ANSWERMolecules are made up of atoms connected together.
In solids, molecules are packed closely together. In gases, molecules are spread far apart.
You can cause substances to change state by adding energy, most often thermal energy (heat).
Ice melting and turning into liquid and water boiling and evaporating into a gas. Any instance of melting or freezing would be considered a phase change.
When ice melts, the solid turns into a liquid. When you burn something, energy causes an old substance to change into a new substance.
It is a chemical change because your saliva causes a chemical reaction and new substances are formed.
After Video
How is a physical change different from a chemical change? ANSWERIn a physical change, no new substances are formed. In a chemical change, new substances are formed.
If a new substance is formed, it has different properties.
Steel wool burning, which causes the iron to combine with oxygen and form iron oxide.
By testing the properties before and after the reaction. Iron is flammable and will light on fire when touched with a battery. After combining with oxygen, it is no longer flammable because the properties have changed.
Magnetism, flammability, electricity, density, and odor
A catalyst helps the chemical reaction happen faster, but it does not become a part of the new substance.
- Vocabulary
- Atoms DEFINE
The smallest particle of matter made up of protons, neutrons, and electrons.
- Molecules DEFINE
More than one atom combined to form a substance (e.g., oxygen – O2).
- Reactants DEFINE
Substances that are combined to form products in a chemical reaction.
- Products DEFINE
The result of substances being combined in a chemical reaction.
- Chemical change DEFINE
Chemicals combining to cause new substances to be formed.
- Physical change DEFINE
A change in state of matter where no new substance is formed.
- Properties DEFINE
Characteristics of matter that can be used to identify substances.
- Catalyst DEFINE
A chemical that makes a chemical reaction happen faster.
- Chemical engineer DEFINE
A scientist who uses chemical reactions to solve problems.
- Materials scientist DEFINE
A scientist who uses chemical reactions to make new materials.
- Atoms DEFINE
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