Properties of Matter and Chemical Changes

Protons: Positively charged particles within an atom.
Neutrons: Neutrally charged particles within an atom.
Electrons: Negatively charged particles that orbit the nucleus of an atom.
Molecular Cohesion: Molecules stay together due to the electrostatic attraction between the positively charged protons of one atom and the negatively charged electrons of another atom, and vice versa. This mutual attraction pulls atoms together to form molecules.

Mechanism: Radioactivity occurs when an atomic nucleus becomes too large and unstable. The internal forces within the nucleus (protons pushing on each other) overcome the strong nuclear force that holds it together.
Analogy: Imagine a small, tight group of people hugging, staying compact. As the group grows larger and larger (like trying to hug an entire campus), the individuals at the edges start to break away because the circle becomes too big to maintain cohesion. Similarly, an excessively large nucleus starts pushing on itself, leading to instability and the breaking away of particles or energy.
Decomposition: No chemical transformation can decompose a radioactive substance in the way chemical reactions decompose compounds. Radioactivity involves nuclear changes, not chemical ones.

Compressed Gases: These are gases held under high pressure, often in large tanks (e.g., as tall as a person).
Example Mixture: Combining $O<em>2$ gas (oxygen) and $H</em>2$ gas (hydrogen) creates a mixture. The individual substances are mixed together but not chemically bonded to form a new substance.
Mixture Definition: A mixture is composed of different substances that are physically combined but retain their individual chemical identities (e.g., $O<em>2$ and $H</em>2$ gas).
Hydrocarbons: Compounds made primarily of hydrogen and carbon. Octane is an example of a gas that is a hydrocarbon and contains eight carbon atoms.

Salt Water Example: When making salt water, if not all the salt dissolves and some flakes settle at the bottom of the glass, it indicates a specific type of solution state.
Saturation Levels Analogy (Movie Theater/Classroom Seats):
- Unsaturated Solution: There are still