CHEMISTRY

📘 Lesson 1: Introduction to Atoms

🔹 Definition of Atom

• Smallest unit of an element

• Building blocks of all matter

🔹 Subatomic Particles

• Atomic Number = # of protons = # of electrons (in neutral atom)

• Mass Number = # of protons + # of neutrons

🔹 Evolution of Atomic Models

1. Leucippus & Democritus

   • All matter is made of tiny, indivisible particles called atomos.

2. John Dalton (1803) – Billiard Ball Model

   • Atoms are solid spheres.

   • Atoms of the same element are identical.

   • Different elements = different atoms.

3. J.J. Thomson (1904) – Plum Pudding Model

   • Atom is a positively charged sphere with scattered electrons.

   • Discovered the electron.

4. Ernest Rutherford (1911) – Nuclear Model

   • Discovered the proton.

   • Atom has a dense, positive nucleus.

   • Electrons orbit around the nucleus.

5. Niels Bohr (1913) – Planetary Model

   • Electrons orbit the nucleus in fixed energy levels.

6. James Chadwick

   • Discovered the neutron (neutral particle in the nucleus).

7. Erwin Schrödinger (1926) – Quantum Mechanical Model

   • Electrons move in "clouds of probability" (orbitals).

   • Exact location of an electron is uncertain.

🔹 Sample Element Info

Example: Calcium (Ca)

• Atomic Number: 20

• Atomic Mass: 40

• Protons: 20

• Neutrons: 20

• Electrons: 20

📗 Lesson 2: Matter and Its Properties

🔹 Matter vs Non-Matter

• Matter: has mass and occupies space (e.g., water, air, metal)

• Non-matter: no mass/volume (e.g., light, heat)

🔹 Classification of Matter

1. Pure Substances

   • Fixed composition; cannot be physically separated
     a. Elements: one type of atom (e.g., oxygen, iron)
     b. Compounds: 2+ atoms chemically bonded (e.g., H₂O)

2. Mixtures

   • Two or more substances physically combined
     a. Homogeneous (Solution) – uniform (e.g., air, salt water)
     b. Heterogeneous – visible parts (e.g., sand + water)

🔹 Elements Classification

• Metals: solid, shiny, good conductors (e.g., iron)

• Non-metals: poor conductors, brittle (e.g., oxygen)

• Metalloids: properties of both (e.g., silicon)

🔹 Types of Mixtures

• Colloid: particles don’t settle (e.g., milk, fog)

• Suspension: large particles settle over time (e.g., muddy water)

🔹 Types of Solutions

📙 Lesson 3: Separation Methods of Mixtures

🔹 1. Filtration

• Separates insoluble solid from liquid

• Uses: filter paper + funnel

• Solid (residue) remains on paper; liquid (filtrate) passes through

🔹 2. Decantation

• Separates liquid from solid after solid settles

• Pour out the liquid carefully without disturbing the solid

🔹 3. Distillation

• Separates liquid from mixture by boiling and condensing

• Simple Distillation: used when impurities are not volatile

• Fractional Distillation: used for separating two or more liquids with different boiling points

🔹 4. Dissolution

• Separates soluble + insoluble solids

• Use a solvent to dissolve the soluble one

🔹 5. Chromatography

• Separates substances based on how they move through a stationary phase

• Components move at different speeds

• Used for inks, dyes, etc.

  • Mobile phase: solvent

  • Stationary phase: paper/material

📘 PHYSICAL AND CHEMICAL REACTIONS

🔹 Physical Change / Reaction

• Definition: A change in a substance that does not change its chemical identity.

• Only affects appearance, shape, size, or state (solid, liquid, gas).

• No new substance is formed.

Common Examples:

• Melting ice

• Boiling water

• Cutting paper

• Dissolving sugar in water

• Crushing a can

Clues of a Physical Change:

• Change in shape or size

• Change in state (melting, boiling, freezing)

• Easily reversible

• No new substance formed

🔹 Chemical Change / Reaction

• Definition: A change that results in the formation of a new substance with different properties.

• Usually not easily reversible.

Common Examples:

• Burning wood

• Rusting iron

• Cooking an egg

• Baking a cake

• Vinegar + baking soda reaction

Clues of a Chemical Change:

• Color change

• Gas production (bubbles/fizz)

• Formation of a solid (precipitate)

• Temperature or light change

• New odor

• Cannot be easily reversed

🔹 STATES OF MATTER (with BEC)

1. Solid

   • Definite shape and volume

   • Particles tightly packed

   • Vibrate in place

   • Low energy

   • Example: Ice, rock

2. Liquid

   • Definite volume, no definite shape

   • Particles move past each other

   • Takes the shape of its container

   • Medium energy

   • Example: Water, oil

3. Gas

   • No definite shape or volume

   • Particles move freely and fast

   • Fills entire space available

   • High energy

   • Example: Oxygen, air

4. Plasma

   • Ionized gas (charged particles)

   • Extremely high energy

   • Found in stars, lightning, neon signs

   • Example: Sun, fluorescent lights

5. Bose-Einstein Condensate (BEC)

   • Predicted by Einstein and Bose in 1920s

   • Formed at extremely low temperatures (near absolute zero)

   • Atoms clump together and act as a single particle

   • Very slow movement; almost no energy

   • Used in quantum physics research

   • Example: Rubidium gas cooled to near 0 K

🔹 Changes in States of Matter (Physical Changes)