Modelo atômico de Thomson - Brasil Escola

Summary

In this lesson, the teacher explains Thomson's atomic model, famously known as the 'plum pudding' model. Based on experiments with cathode rays, Thomson discovered the electron, suggesting that atoms are spherical, neutral, and divisible. He theorized that atoms consist of a positive sphere with negative electrons embedded within it. Thomson also introduced the idea that electrons can move between atoms. The lesson includes a practical analogy using modeling clay to illustrate how the positive and negative charges interact within an atom, making complex concepts more accessible. The session ends with a quick quiz on Thomson's contributions to atomic theory.

Takeaways

• 😀 The Thomson atomic model, also known as the plum pudding model, proposes that atoms are spherical with positive charge spread throughout and negative electrons embedded in it.
• 😀 The model was based on experiments with a cathode ray tube (Crookes' tube) that led to the discovery of the electron.
• 😀 The Thomson model suggests that atoms are not solid but have a diffuse positive charge with negative electrons scattered inside.
• 😀 Thomson’s discovery of the electron challenged previous atomic theories and introduced the concept of subatomic particles.
• 😀 The atom in Thomson’s model is considered divisible, unlike Dalton’s model, which described atoms as indivisible.
• 😀 The electrons in Thomson’s atom were not fixed but could move between atoms, indicating a more dynamic structure.
• 😀 The analogy of an amoeba covered with dirt was used to illustrate the structure of the Thomson model, where the amoeba represents the positive charge and the dirt represents the electrons.
• 😀 Thomson proposed that atoms are neutral, balancing the negative charge of electrons with the positive charge spread throughout.
• 😀 Thomson’s contribution to atomic theory included determining the relationship between the mass and charge of the electron.
• 😀 The exercise in the lesson reviewed the contributions of Thomson, confirming that he discovered subatomic particles like electrons and not the nucleus or energy levels of electrons.

Q & A

What was the key discovery made by Thomson related to the atomic model?

Thomson's key discovery was the existence of the electron, a negatively charged particle within the atom. This was a significant contribution to the development of the atomic model.

What was the model of the atom proposed by Thomson called?

Thomson's model of the atom was known as the 'Plum Pudding Model,' which depicted the atom as a large positively charged sphere with negatively charged electrons embedded within it.

What experiment led to the discovery of the electron?

Thomson's discovery of the electron was based on experiments involving a cathode ray tube, also referred to as Crookes' tube, which showed that cathode rays were negatively charged particles.

How did Thomson describe the structure of the atom?

Thomson described the atom as spherical in shape, non-massive, and neutral, with negative electrons embedded in a positive 'pudding' like substance.

Why did Thomson believe that the atom was divisible?

Thomson believed the atom was divisible because he discovered the electron as a subatomic particle, which implied that the atom could be broken down into smaller components.

What does the term 'pudim de passas' refer to in Thomson's model?

'Pudim de passas' refers to the 'Plum Pudding Model,' where the positive charge of the atom is represented as the 'pudding,' and the negative electrons are represented as the 'raisins' embedded within it.

How did Thomson explain the transfer of electrons between atoms?

Thomson proposed that electrons were not fixed within an atom and could be transferred from one atom to another, a concept that laid the foundation for understanding chemical reactions and electric conductivity.

What was Thomson's contribution to the concept of the electron?

Thomson's contribution was identifying the electron as a subatomic particle and determining its negative charge. This was fundamental in shaping our understanding of atomic structure.

What does the amoeba analogy represent in the explanation of the Thomson model?

In the amoeba analogy, the amoeba represents the positive charge of the atom, while the dirt and particles embedded in it represent the electrons. This helps visualize how electrons are spread throughout the positive sphere.

What did Thomson’s model suggest about the atom's overall charge?

Thomson’s model suggested that the atom was neutral overall, with positive and negative charges balancing each other out, as the electrons’ negative charge was countered by the positive charge in the atom's core.