G8-Science-LEC-3-Atomic-Models drscription topics.pptx

This ppt containe all about stomic models and its effects and types

1. Atomic Models

2. Democritus and Leucippus Leucippus - Matter is made up of indivisible particles (atoms) and that these particles exist in a void. Democritus (c. 400 BCE) - matter is made up of tiny, indivisible particles called " atomos ." Though speculative, his idea laid the foundation for the atomic theory.

3. Dalton’s Model John Dalton (1766-1844) All matter is made of small indivisible particles called atoms. Each element has unique atoms with identical properties. Compounds are formed when atoms of different elements combined chemically. Atoms of compounds rearrange during chemical reactions. They are neither created nor destroyed nor transformed into atoms of another element. Dalton's model was a simple, solid sphere with no internal structure.

4. Dalton’s Model

5. Thomson’s Model Joseph John Thomson (1856–1940) He discovered the electron. This led to the Plum Pudding Model, where the atom was thought to consist of a positively charged "pudding" with negatively charged "plums" (electrons) embedded within it. The negatively charged electrons balance the positive charges, thus atoms usually have neutral electrical charge

6. Nuclear Model Ernest Rutherford (1871-1937) Rutherford's gold foil experiment revealed that the atom has a small, dense, positively charged nucleus at its center, surrounded by electrons. This led to the Nuclear Model, where most of the atom's mass and positive charge is concentrated in the nucleus, with electrons orbiting around it.

7. Nuclear Model The radius of a nucleus is extremely small (about 1/100,000 of an atom) Rutherford discovered Protons James Chadwick discovered the Neutrons What..? That’s 1 meter/100 km

8. Bohr’s Model Niels Bohr (1885-1962) Observed that electrons in an atom exist in specific regions at specific distance from the nucleus. Bohr refined Rutherford’s model by proposing that electrons orbit the nucleus in fixed paths or energy levels.

9. Bohr’s Model Electrons could jump between these orbits but would absorb or emit specific amounts of energy ( quantized energy levels ). He theorized that electrons have several orbits

10. Bohr’s Model Electrons that orbit closest to the nucleus has the lowest energy Electrons that orbit away from the nucleus has high energy level Electrons can release or absorb energy and transfer from one orbit into another

11. Quantum Mechanical Model Erwin Schrödinger in (1887-1961) Electrons in probabilistic orbitals (1926). Most accurate and widely accepted model Quantum mechanical model, electrons are treated as probability waves (wave functions) rather than tiny solid particles. The exact position of an electron cannot be determined precisely, but we can calculate the probability of finding an electron in a certain region of space. Rather than orbiting the nucleus in fixed, circular paths as in earlier models (like Bohr's), electrons are found in orbitals. Orbitals are regions of space where there is a high probability of finding an electron.

12. Quantum Mechanical Model These orbitals have different shapes and sizes depending on the energy level of the electron. For example, s orbitals are spherical, while p orbitals are dumbbell-shaped.

13. Quantum Mechanical Model

14. Electron Distribution in energy levels and Sub-shells