The Structure of the Atom

Who originally proposed that matter is composed of tiny, indivisible particles?

• Aristotle

• Democritus

• Dalton

• Crookes

Whose work is credited with being the beginning of modern atomic theory?

• Democritus

• John Dalton

• Aristotle

• William Crookes

The nucleus of an atom include:

• protons and electrons

• electrons and neutrons

• protons and neutrons

• only protons

Dalton's theory of the atom is related with the idea of the conservation of mass.

• True

• False

The accidental discovery of the cathode ray led to the invention of the ________.

• radio

• lightbulb

• television

• atomic bomb

Which sub-particle is located outside the nucleus and have a negative charge?

• atom

• proton

• neutron

• electron

Who determined the charge of an electron using the oil-drop apparatus?

• Robert Millikan

• John Dalton

• William Crookes

• Aristotle

Ernest Rutherford modified Thomson's plum pudding model by describing the existence of ___________ in an atom.

• the neutrons

• the nucleus

• an electrical cloud

• a positive cloud

The number of neutrons in an atom is referred to as the atomic number.

• True

• False

The element (Li) is in the group 1 and period 2, its atomic number is 3. How many protons (Li) have?

• 1

• 2

• 3

• 6