The Democritus Model

Drawing and Description of Experimental Design
The Democritus Model explained that all matter is made of small subatomic particles referred to as atoms. Atoms can not be destroyed nor created. Democritus further added that atoms are the smallest commodity of matter.
Conclusions

In conclusion, the Democritus Model is a basic representation of atoms and how all matter is made of small subatomic particles, referred to as atoms.

Pros

-First proposal of atoms

-Start of atomic theory

-Unique atoms for each element

Cons

-Infinity types of atoms

-Invisibly of atoms

-Excess amount of elements

-Macro properties

Dalton viewed atoms as solid, indivisible spheres, leading to the concept of the atom as the fundamental building block of matter.

Dalton's theory was based on experimental observations rather than a specific single experiment. He used data from chemical reactions and gas laws to support his ideas.

Dalton's model laid the foundation for modern chemistry by introducing the idea of atoms as the fundamental units of matter and establishing a framework for understanding chemical reactions based on atomic theory.

Pros

• Introduced the concept of the atom as the basic unit of matter, which was a significant advancement in chemistry.

• Established a systematic way of understanding chemical reactions and compounds.

• Laid the groundwork for future atomic theories and models.

Cons

• Atoms are not indivisible; later discoveries revealed subatomic particles (protons, neutrons, electrons).

• Dalton's theory did not explain the existence of isotopes (atoms of the same element with different masses).

• Limited by the scientific knowledge of the time; did not incorporate electromagnetic forces or the quantum nature of matter.

Thomson's atomic model proposed that atoms are not indivisible, as Dalton suggested. Instead, he introduced the concept of subatomic particles:

• Electrons: Discovered through cathode ray experiments, Thomson suggested that these negatively charged particles were scattered throughout a positively charged "soup" of matter.

• The model implied that the atom is a homogeneous sphere of positive charge with electrons embedded in it, counterbalancing the positive charge.

Thomson's conclusions were based on his experiments with cathode rays:

1. Cathode Ray Tube Experiments: Thomson observed the behavior of cathode rays (streams of electrons) in electric and magnetic fields.

   • He found that these rays were deflected by electric fields, indicating they were composed of negatively charged particles (later named electrons).

   • The degree of deflection helped him estimate the charge-to-mass ratio of the electron.

     
     

     Thomson concluded that atoms are made up of smaller particles (electrons) and proposed the "plum pudding" model as a way to explain the distribution of these electrons within an atom.

Pros

• Introduced the concept of subatomic particles, expanding on Dalton's theory of the indivisible atom.

• Provided a framework for understanding the structure of the atom that paved the way for future discoveries.

• Helped to establish the field of atomic physics and encouraged further research into atomic structure.

Cons

• The plum pudding model could not explain the results of later experiments, particularly Rutherford's gold foil experiment, which showed that atoms have a dense nucleus.

• Lacked a precise arrangement of electrons and did not account for the existence of other subatomic particles (protons and neutrons).

• The model was eventually replaced by the nuclear model of the atom, which introduced a central nucleus and orbiting electrons.

The Nuclear Model

Description of Atomic Model`

Ernest Rutherford nuclear model changed the atomic theory by showing that atoms have a small, dense, positively charge center called the nucleus. By his experiment called Gold Foil he was able to tell that most of an atoms mass and positive charge are concentrated in the nucleus, with electrons moving around in an empty space.He set the foundation for modern atomic physics.

Drawing and Description of Experimental Design

Conclusions

The atom has a positive center known as nucleus and it has the most of the atoms mass and very big empty space where electrons move around.

Pros

-Show's electrons and location

-Foundation for future models

Cons

-It does not explain the stability of the atom

-Incomplete description of electrons

Bohr's atomic model introduced the idea of quantized electron orbits. Electrons orbit the atomic nucleus in specific energy levels or "shells." Each orbit represents a specific, fixed energy level, where:

• Electrons in an orbit don’t emit energy.

• Electrons can jump between levels, absorbing or releasing a photon equal to the energy difference between orbits.

Bohr based his model on the hydrogen atom's emission spectrum and prior findings from Rutherford’s gold foil experiment. While Bohr did not conduct an experiment specifically, he interpreted the spectral lines of hydrogen and deduced electron orbits with quantized energy levels.

Bohr's model explained the stability of atoms and the emission spectra for hydrogen. It led to the realization that atomic energy levels are quantized, laying groundwork for quantum mechanics.

Pros

• Explained atomic stability and emission spectra.

• Introduced quantized electron orbits, a key idea in quantum theory.

• Provided a foundation for later atomic models, particularly the quantum mechanical model.

Cons

• Limited to explaining hydrogen; didn’t work for multi-electron atoms.

• Failed to account for the wave properties of electrons (addressed in later quantum models).

• Couldn’t explain finer spectral lines or the Zeeman effect (splitting of spectral lines in a magnetic field).

Schrödinger's model describes electrons as wave functions, meaning their position and momentum cannot be precisely determined simultaneously (as per Heisenberg's uncertainty principle). The model introduces

Schrödinger used mathematical equations derived from quantum mechanics to describe the behavior of electrons. His work did not rely on specific experiments but rather on the principles of quantum mechanics and the understanding of atomic structure at that time.

Schrödinger's model successfully explained the behavior of electrons in atoms, provided a clearer understanding of atomic structure, and predicted the arrangement of electrons in multi-electron atoms. This model laid the foundation for modern quantum chemistry and atomic physics.

Pros

• Accurately describes the electron distribution and behavior in atoms, including multi-electron systems.

• Introduced the concept of orbitals, allowing for a more comprehensive understanding of chemical bonding and molecular structure.

• Incorporated wave-particle duality, aligning with experimental observations and the principles of quantum mechanics.

Cons

.The mathematics involved can be complex and difficult to interpret, making it less intuitive than earlier models.

• Does not provide a definitive position for electrons, only probabilities, which can be conceptually challenging.

• Relies on advanced mathematics and quantum mechanics, which can limit its accessibility for students new to the subject.

Description of Atomic Model

James Chadwick using electricity and polonium in a vacuumed sealed box James Chadwick concluded from unknown radiation that accelerated out was neutrons

Drawing and Description of Experimental Design
Protons and neutrons bound together as the atom's nucleus, with negatively charged electrons occupying energy levels surrounding the nucleus.
Conclusions

Atoms consist of not just protons and electrons but also neutrons.

Pros

-Discovered Neutrons

-Shows Neutrons

-Revolutionized Science

Cons

-Hard to Energy Levels

-Doesn't describe electron location other than outside the nucleus