Matter:

Properties, classification, and types of matter.
Physical and Chemical Changes: Understanding the differences.
Atomic Structure: Fundamental particles, atomic number, mass number, etc.
The Periodic Table: Elements, groups, periods, and properties of elements.
Chemical Bonding: Ionic and covalent bonding.
Metals and Non-Metals: Properties, reactivity, and uses.
Study of Compounds: Preparation, properties, and uses of common compounds like water, hydrogen peroxide, etc