5.4 Development of the atomic model

Who was the first scientist to theorize about the atom in the year 442 BCE?

• A) Aristotle

• B) John Dalton

• C) Democritus

• D) Joseph John Thomson

What did Aristotle believe matter on Earth was made up of?

• A) Atoms

• B) Cells

• C) Four elements: earth, air, fire, and water

• D) Subatomic particles

Which scientist is credited for igniting research into modern atomic theory in 1803, more than 2000 years after Democritus first proposed his ideas on the atom?

• A) Aristotle

• B) John Dalton

• C) Democritus

• D) Joseph John Thomson

Who was the first scientist to discover particles smaller than the atom, disproving Dalton's and Democritus' theories?

• A) Aristotle

• B) John Dalton

• C) Democritus

• D) Joseph John Thomson

What was the first subatomic particle to be discovered by Joseph John Thomson?

• A) Proton

• B) Neutron

• C) Electron

• D) Positron

What did J.J. Thomson propose in his model of the atom?

• Atoms are composed entirely of negative charges.

• Atoms have a small, dense nucleus.

• Atoms are neutral, with scattered negative charges in a 'sea' of positive charge.

• Atoms are made up of a lattice of positive charges with electrons in between.

What was the outcome of the gold foil experiment conducted by Ernest Rutherford?

• It confirmed the plum pudding model.

• It showed that the atom was mostly empty space.

• It demonstrated that electrons orbit the nucleus in fixed paths.

• It proved that atoms are indivisible.

According to the gold foil experiment, where is most of the mass of the atom concentrated?

• Evenly distributed throughout the atom

• In the electrons

• In a central nucleus

• On the outer edges of the atom

What did Rutherford's atomic model assume about the nucleus?

• It was negatively charged.

• It was positively charged.

• It had no charge.

• It was composed of neutrons only.

According to the text, what did Rutherford conclude about electrons in his atomic model?

• Electrons were stationary within the atom.

• Electrons orbited around the nucleus.

• Electrons were embedded in the nucleus.

• Electrons repelled alpha particles.