1.3.2 The discovery of the electron, nucleus, and proton

• Protons were confirmed in 1920.

  True
• Protons account for half of the nucleus' mass.


  True
• What atomic property do protons determine?

  Atomic number
• The plum pudding model describes uniform charge distribution within the atom.


  True
• What is the role of protons in determining an element's identity?

  Atomic number
• Who proposed the existence of protons?

  Ernest Rutherford
• Most alpha particles in Rutherford's experiment passed straight through the gold foil.

  True
• The alpha particles are blocked by the thin gold foil in the experiment.

  False
• Match the charge with its location in Thomson's model:

  Positive charge ↔️ Sphere

  Negative charge ↔️ Electrons inside
• What charge did Thomson determine electrons to have?

  Negative
• What type of particles did Rutherford fire at the gold foil in his experiment?

  Alpha particles
• What type of charge do protons have?

  Positive
• What was Thomson's plum pudding model the first atomic model to show?

  Electrons in positive charge
• Thomson's experiments showed that cathode rays were deflected by a positively charged plate.


  True
• What atomic model is depicted in the image?

  Plum pudding model
• What shape did Thomson propose for the positive charge in his atomic model?

  Sphere
• The positive charge in Thomson's model is uniformly distributed throughout the atom.

  True
• What type of particle is emitted by the radium source in the experiment?

  Alpha particle
• Match the property of protons with its description:

  Charge ↔️ Positive

  Location ↔️ Nucleus

  Determination ↔️ Atomic number
• What is the charge of the sphere in Thomson's atomic model?

  Positively charged
• Thomson's plum pudding model suggests that an atom has a neutral overall charge.

  True
• The alpha particles are blocked by the thin gold foil in the experiment.

  False
• What did the majority of alpha particles passing through the gold foil indicate about the atom's structure?

  Atoms are mostly empty space
• Electrons orbit the nucleus in the surrounding empty space.


  True
• Rutherford's gold foil experiment confirmed Dalton's atomic theory.

  False
• What did the deflection of some alpha particles in Rutherford's experiment suggest about the atom?

  Positive charge is concentrated
• Match the result of Rutherford's experiment with its interpretation:

  Most particles through ↔️ Atom is mostly empty space

  Some deflected slightly ↔️ Positive charge is concentrated

  Very few bounced back ↔️ Nucleus is dense and small
• What type of particle is emitted by the radium source in the experiment?

  Alpha particle
• The nucleus is much smaller and denser than the rest of the atom.


  True
• What did the gold foil experiment demonstrate about the structure of atoms?

  Atomic nucleus
• Who discovered the electron in 1897?

  J.J. Thomson
• Where are protons located in an atom?

  Nucleus
• In the Rutherford model, electrons are scattered randomly within the atom.

  False
• The electrons in Thomson's model are embedded within a positively charged sphere


  True
• Which atomic model does not include a nucleus?

  Plum pudding model
• What is the primary difference between Thomson's plum pudding model and Rutherford's model?

  Arrangement of charges
• What experiment proved Rutherford's model more accurate?

  Gold foil experiment
• Order the following features according to their appearance in the plum pudding model first and then the Rutherford model:

  1️⃣ Uniform charge distribution

  2️⃣ Scattered electron placement

  3️⃣ Dense charge distribution

  4️⃣ Orbital electron placement
• Rutherford proposed the proton in 1920.


  True
• Rutherford's model accurately describes the dual nature of electrons as both particles and waves.

  False