ATOMS & STRUCTURE
What are the three subatomic particles?
Protons, Neutrons, and Electrons.
What is the formula for density?
d = m / V.
Q: Is "melting ice" a physical or chemical change?
A: Physical change.
Q: What do we call a substance made of only one type of atom?
A: Element.
What are the "starting materials" in a chemical reaction called?
A: Reactants.
Which particle is found in the shells (orbitals)?
Electrons.
If an object floats, is its density lower than water?
Yes.
Q: Give one example of a chemical change.
A: Burning, rusting, or souring.
Q: How is a compound different from a mixture?
A: Compounds are chemically bonded; mixtures are just physically mixed.
What are the three signs that a chemical reaction is happening?
Gas bubbles, color change, temperature change.
What is the charge of a neutron?
Neutral (No charge).
What is the unit of density?
g/cm^3.
Does a new substance form in a physical change?
A: No.
Q: What is the best way to separate salt from sea water?
A: Evaporation
Q: Explain the "Law of Conservation of Mass" in one sentence.
A: Mass cannot be created or destroyed (Total mass stays the same).
Where is most of the atom's mass located?
In the nucleus.
Does density change if you cut an object?
No.
Q: Is "digestion of food" chemical?
A: Yes.
Is "Air" a compound or a mixture? Why?
It's a mixture of different gases like Oxygen and Nitrogen.
In the reaction C + O_2 \rightarrow CO_2, what is the product?
Carbon dioxide (CO_2).
What is the atomic number?
The number of protons.
What do you need to measure to find density?
Mass and Volume.
Q: Is "breaking glass" physical?
A: Yes.
What is the smallest unit of an element that keeps its properties?
An atom.
Why is photosynthesis considered a chemical reaction?
A: Because it turns water and CO_2 into a new substance (Glucose/Oxygen).