Summary of "9.sınıf kimya 1.dönem 1.yazılı 2025-2026 | Yazılı Provası"

Summary of the Video

“9.sınıf kimya 1.dönem 1.yazılı 2025-2026 | Yazılı Provası”

This video is an educational chemistry review and practice session aimed at 9th-grade students preparing for their first term written exam in chemistry. The instructor, despite recovering from surgery, walks students through typical exam questions, explains key chemistry concepts, and provides detailed methodologies and explanations to help students succeed.

Main Ideas, Concepts, and Lessons

1. Lead in Ceramic Glaze and Its Toxicity

Lead is sometimes added to ceramic glaze to give a shiny appearance, especially in low-quality products.
Acidic beverages (like lemonade, vinegar, cola, soda) can cause small amounts of lead to leach into the liquid, especially with longer contact time and higher temperature.
Lead is a toxic heavy metal harmful to the nervous system, liver, and kidneys.
Examples of acidic liquids: lemon juice, vinegar, cola, soda.
Neutral or less acidic liquids: water, milk, buttermilk.
Safer alternatives to lead-containing ceramics: glass and stainless steel, with glass being the healthiest option.

2. Chemistry Laboratory Safety and Equipment

Common lab equipment includes thermometer, pipette, beaker, tripod, and Bunsen burner.
Proper use of equipment:
- Tripod and wire gauze support beakers during heating.
- Thermometer should be inserted gently with vaseline or glycerin to avoid breakage.
Common mistakes and their dangers:
- Pouring acid without gloves (acid is corrosive and damages skin).
- Forcing thermometer into glass stopper (risk of breakage and mercury poisoning).
- Heating acid without a lid or fume hood (risk of splashing and inhalation).
- Using mouth suction to draw liquid into pipette instead of a pipette bulb (risk of poisoning).
- Adding water to acid instead of acid to water (causes splashing and burns).
Safety pictograms to use when working with acids: corrosive, gloves, apron, mask, goggles. Radioactive and cutting tool symbols are unnecessary here.

3. Atomic Models and Subatomic Particles

Overview of atomic structure:
- Atom consists of nucleus (protons and neutrons) and electron cloud (electrons).
- Proton: positively charged particle in nucleus.
- Neutron: neutral particle in nucleus.
- Electron: negatively charged particle in electron cloud.
Historical development of atomic models:
- Dalton: solid sphere model, atoms indivisible.
- Thomson: “plum pudding” model with electrons embedded in positive sphere.
- Rutherford: nucleus concept, electrons orbiting nucleus, mostly empty space.
- Bohr: electrons orbit nucleus at fixed energy levels.
- Heisenberg/Modern Quantum Model: electron cloud/orbitals, uncertainty principle.
Scientific knowledge is modifiable and develops over time as new discoveries are made.

4. Atomic Orbitals and Electron Configuration

Orbitals: regions where electrons are likely to be found.
- S orbital: spherical shape, found at all energy levels.
- P orbitals: dumbbell-shaped, exist from 2nd energy level, three orbitals (px, py, pz) with equal energy.
- D orbitals: five orbitals, start at 3rd energy level.
- F orbitals: seven orbitals, start at 4th energy level.
Energy order of orbitals (lowest to highest): 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s …
Exceptions in electron filling order (e.g., chromium and copper) where 4s¹ 3d⁵ or 4s¹ 3d¹⁰ configurations occur.
Hund’s Rule: electrons fill orbitals singly first with parallel spins before pairing.
Pauli Exclusion Principle: no two electrons in the same orbital can have the same spin.
Aufbau Principle: electrons fill orbitals starting from the lowest energy level.
Maximum electrons per orbital type:
- S: 2 electrons
- P: 6 electrons (3 orbitals × 2 electrons)
- D: 10 electrons (5 orbitals × 2 electrons)
- F: 14 electrons (7 orbitals × 2 electrons)
Orbital diagrams and electron configurations must comply with these principles.
Spherical symmetry occurs when orbitals are either fully filled or half-filled in a specific pattern.

5. Exam Preparation Tips and Encouragement

Focus on electron configurations, orbital shapes, and atomic models.
Review previous videos and materials on the channel for comprehensive understanding.
Use PDFs and practice questions provided by the instructor.
Support from other teachers on the platform (Zedu teachers) is available.
The instructor shares his personal motivation and dream of establishing a laboratory and encourages students to subscribe and support the channel.

Methodology / Instructions for Students

When comparing lead migration in ceramics:
- Use acidic and neutral liquids (e.g., cola vs. water).
- Observe effect of temperature and contact time.
Lab safety:
- Always wear gloves when handling acids.
- Insert thermometers carefully using lubricants like vaseline or glycerin.
- Use pipette bulbs instead of mouth suction.
- Add acid to water, never water to acid.
- Use protective equipment: goggles, apron, gloves, mask.
Electron configuration writing:
- Follow Aufbau principle (fill lowest energy orbitals first).
- Apply Hund’s rule (fill orbitals singly first).
- Apply Pauli exclusion principle (opposite spins in same orbital).
- Know starting energy levels for orbitals (S from 1, P from 2, D from 3, F from 4).
Understand the shapes and energy order of orbitals.
Recognize exceptions in electron configurations (chromium, copper).
Practice orbital diagrams with correct spin directions.

Speakers / Sources Featured

Main Speaker: The chemistry teacher/instructor (unnamed) who is recovering from surgery but actively teaching and providing exam preparation.
Other Mentions: Zedu teachers (colleagues supporting students on the platform).

This summary captures the key educational content, explanations, and exam preparation strategies presented in the video.