Physical vs. Chemical Changes
What is a physical change?
A change that does not alter the substance itself.
What is another name for a chemical change?
A chemical reaction.
What does the Law of Conservation of Matter state?
Mass cannot be created or destroyed.
What is a property of matter?
A characteristic that can be observed.
What occurs during a chemical change?
Matter is turned into a new substance with new properties.
What is a chemical change?
A change that produces a new substance.
What are reactants?
Substances that take part in a chemical reaction.
What must be true about the number of atoms in reactants and products?
They must be equal.
What are physical properties?
Properties that can be observed without changing the substance.
What is one sign that a chemical change has occurred?
Formation of gas or a permanent color change.
Give an example of a physical change.
Melting ice or boiling water.
What does the arrow in a chemical equation represent?
It means "produces" or "yields."
How does this law apply to a chemical reaction?
Whatever is on one side must be on the other side.
List three examples of physical properties.
Color, mass, and density.
Why can't we see some chemical properties?
Because they can only be observed while altering the substance.
What happens to the substance during a chemical change?
It transforms into a new substance with different properties.
Write the chemical equation for sodium and chlorine combining to form salt.
Na + Cl ARROW NaCl
Give an example of how matter is conserved in a reaction.
In burning wood, the mass of the ashes, gases, and other products equals the mass of the original wood.
What are chemical properties?
Properties that can be observed during a chemical reaction.
Can chemical changes be reversed easily?
Usually not, as they create new substances.
How can you tell if a physical change has occurred?
The substance remains the same and its properties do not change.
What can you say about the atoms on both sides of a chemical equation?
The type and number of atoms are the same on both sides.
What types of atoms in reactants must equal the types in products?
The type of atoms must be the same.
Give an example of a chemical property.
Flammability or reactivity.
How can temperature changes indicate a chemical reaction?
If the temperature increases or decreases, it may signal a chemical change.