The History of the Atom

What was the Ancient Greek word Democritus used to describe particles of matter?

Answer explanation

Democritus called the particles in matter 'atomos', which means 'indivisible'.

Other philosophers of Democritus' time disagreed with him. For example, Aristotle argued that matter was made up of four ________?

Answer explanation

These 4 elements were air, water, earth and fire.

After Democritus, it took over 2000 years for atomic theory to be investigated properly. Who was the next important figure in the history of atomic theory?

• JJ Thomson

• Niels Bohr

• John Dalton

• Ernest Rutherford

Answer explanation

John Dalton (1766-1844) was the next important figure. He challenged Aristotelian theory.

Which two of the following statements did John Dalton propose about the atom?

• Atoms of a given element are identical in mass and properties

• Atoms have nucleus surrounded by electrons

• Protons are positive particles

• Atoms can neither be created nor destroyed, only rearranged

Answer explanation

Atoms of a given element are identical in mass and properties and can neither be created nor destroyed.

JJ Thomson won the Nobel Prize in 1906 because he discovered the ________

Answer explanation

Thomson discovered the electron.

This is JJ Thomson's model of the atom, nicknamed the 'chocolate chip cookie' or the 'plum pudding'. What is wrong with this model?

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Answer explanation

-There is no nucleus

• -There are no neutrons

• -The electrons are not arranged properly

Ernest Rutherford discovered the nucleus of the atom in his gold foil experiment. What is the charge of the nucleus?

Answer explanation

The charge of the nucleus is positive.

Which scientist is known for proposing the planetary model of the atom?

• Max Planck

• Niels Bohr

• Erwin Schrödinger

• James Chadwick

Answer explanation

Niels Bohr presented the planetary model.

In Niels Bohr's 'planetary' model, he demonstrated that electrons _____ the nucleus.

Answer explanation

He said that they 'orbit' the nucleus like planets.

What is the current atomic model we use today called?

• Electron Model

• Quantum Model

• Nucleus Model

• Orbit Model

Answer explanation

We call it the 'quantum' model.