Sci8-Q2-PART1

In the context of scientific advancements during the late 19th and early 20^th centuries, why is J.J. Thomson’s discovery of the electron was regarded as a major

turning point in the development of atomic theory, and how did it challenge or change the previously accepted models of the atom?

• A It revealed the existence of a dense central nucleus within the atom.

• It introduced the concept that atoms are made up of smaller subatomic

       particles, including negatively charged electrons.

Based on the historical development of atomic theory, which sequences

correctly represent the major contributors and models of the atom in the order they

were proposed, from earliest to most recent?

• A.Thomson → Rutherford → Bohr → Dalton → Schrodinger → Democritus

• B. Dalton → Democritus → Bohr → Rutherford → Thomson → Schrodinger

• C. Democritus → Dalton → Thomson → Rutherford → Bohr → Schrödinger

• D. Bohr → Rutherford → Thomson → Dalton → Schrödinger → Democritus

What conclusion did Rutherford draw from this experiment?

• A. Atoms have no internal structure.

• B. Electrons orbit randomly within atoms.

• C. Atoms are solid and dense throughout.

• D. Atoms have a small, dense, positively charged nucleus.

A student crushes a sugar cube into fine powder. She asks whether it’s possible to keep dividing it until nothing is left. Which explanation applies the shared idea of Democritus and Dalton?

• A. Matter can be divided infinitely.

• B. Division causes matter to vanish.

• C. The smallest particles cannot be divided further.

• D. Atoms can be split into smaller particles until it vanish.

In the Plum Pudding Model, the atom is described as a positively charged

"pudding" with electrons scattered inside. What does this arrangement suggest about the location of electrons?

• A. They are only in the center of the atom.

• B. They are orbiting the nucleus in fixed paths

• C. They are randomly floating outside the atom

• D. They are spread evenly within the positive space

In an animation of Schrödinger’s model, electrons are shown as blurs around the

nucleus. What concept does this best illustrate?

• Electrons have random mass

• Electrons exist in uncertain locations

During a class debate, one student says the atom is mostly empty space. Which

experiment and model support this claim?

• Schrödinger’s cloud model and neutron discovery

• Rutherford’s gold foil experiment and Nuclear Model

Scientists describe an atom as having a dense center called the nucleus, which

contains protons and neutrons. Around this center, much smaller particles move at

high speeds. Based on the description, where are the electrons found in an atom?

• Inside the protons

• Moving around the nucleus

An atom is made up of a dense central nucleus surrounded by moving electrons.

The nucleus contains specific types of subatomic particles. Which two particles are

found in the nucleus of an atom?

• Protons and neutrons

• Protons and electrons

Each element in the periodic table is unique because of a specific property found

      in its atoms. What defines the identity of an element?

• mass number

• Number of protons