Atoms and Elements
● Atom Structure: Atoms are the smallest units of matter. They consist of:
○ Protons: Positively charged particles found in the nucleus.
○ Neutrons: Neutrally charged particles found in the nucleus.
○ Electrons: Negatively charged particles that orbit the nucleus.
● Elements: Pure substances made of only one type of atom. They are represented in
the Periodic Table.
2. The Periodic Table
● Groups/Families: Vertical columns in the periodic table. Elements in the same group
share similar properties (e.g., Group 1: Alkali metals).
● Periods: Horizontal rows. Properties of elements change gradually across a period.
● Metals, Non-Metals, and Metalloids: Metals are good conductors, non-metals are
poor conductors, and metalloids have properties of both.
3. Chemical Reactions
● Reactants and Products: Reactants are substances that start a reaction, and
products are substances formed by the reaction.
● Law of Conservation of Mass: In a chemical reaction, mass is neither created nor
destroyed. The total mass of reactants equals the total mass of products.
● Types of Reactions:
○ Synthesis: Two or more elements or compounds combine to form a single
product (A + B → AB).
○ Decomposition: A compound breaks down into simpler substances (AB → A
+ B).
○ Combustion: A substance reacts with oxygen to produce heat and light (fuel
+ O₂ → CO₂ + H₂O).
4. Cells and Biology
● Cell Theory:
○ All living organisms are made of cells.
○ Cells are the basic units of life.
○ All cells come from pre-existing cells.
● Cell Organelles:
○ Nucleus: Contains genetic material (DNA) and controls cell activities.
○ Mitochondria: The powerhouse of the cell, responsible for producing energy.
○ Chloroplasts (in plant cells): Where photosynthesis occurs.
○ Cell Membrane: Regulates what enters and leaves the cell.
5. Ecology
● Ecosystems: Communities of living organisms interacting with their physical
environment.
● Atom Structure: Atoms are the smallest units of matter. They consist of:
○ Protons: Positively charged particles found in the nucleus.
○ Neutrons: Neutrally charged particles found in the nucleus.
○ Electrons: Negatively charged particles that orbit the nucleus.
● Elements: Pure substances made of only one type of atom. They are represented in
the Periodic Table.
2. The Periodic Table
● Groups/Families: Vertical columns in the periodic table. Elements in the same group
share similar properties (e.g., Group 1: Alkali metals).
● Periods: Horizontal rows. Properties of elements change gradually across a period.
● Metals, Non-Metals, and Metalloids: Metals are good conductors, non-metals are
poor conductors, and metalloids have properties of both.
3. Chemical Reactions
● Reactants and Products: Reactants are substances that start a reaction, and
products are substances formed by the reaction.
● Law of Conservation of Mass: In a chemical reaction, mass is neither created nor
destroyed. The total mass of reactants equals the total mass of products.
● Types of Reactions:
○ Synthesis: Two or more elements or compounds combine to form a single
product (A + B → AB).
○ Decomposition: A compound breaks down into simpler substances (AB → A
+ B).
○ Combustion: A substance reacts with oxygen to produce heat and light (fuel
+ O₂ → CO₂ + H₂O).
4. Cells and Biology
● Cell Theory:
○ All living organisms are made of cells.
○ Cells are the basic units of life.
○ All cells come from pre-existing cells.
● Cell Organelles:
○ Nucleus: Contains genetic material (DNA) and controls cell activities.
○ Mitochondria: The powerhouse of the cell, responsible for producing energy.
○ Chloroplasts (in plant cells): Where photosynthesis occurs.
○ Cell Membrane: Regulates what enters and leaves the cell.
5. Ecology
● Ecosystems: Communities of living organisms interacting with their physical
environment.
