Chemistry - Key Concepts - History of the Atom

<p>Electrons occupy specific energy levels or orbitals. (A)</p> Signup and view all the answers

<p>The idea of specific energy levels proposed by Bohr. (D)</p> Signup and view all the answers

<p>JJ Thompson (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Neutrons</p> Signup and view all the answers

<p>nuclear</p> Signup and view all the answers

<p>Democritus = Proposed the term 'atom' John Dalton = Suggested atoms are spherical Niels Bohr = Calculated electron shells James Chadwick = Discovered neutrons</p> Signup and view all the answers

<p>400 BC = Atoms are indivisible particles 1803 = Atoms are spherical particles 1911 = Discovery of the nucleus 1932 = Identification of neutrons</p> Signup and view all the answers

<p>Democritus = Indivisible atoms John Dalton = Spherical particles JJ Thompson = Plum pudding model Niels Bohr = Electrons in specific shells</p> Signup and view all the answers

<p>Rutherford = Gold foil experiment James Chadwick = Discovery of neutrons JJ Thompson = Negative particles in atom using the plum pudding model Niels Bohr = Calculated specific energy levels of electrons and orbitals</p> Signup and view all the answers

<p>Plum pudding model = Solid sphere with embedded electrons Nuclear model = Based on Bohr and Chadwick's ideas Spherical particle model (Like a snooker ball) = Atoms as round balls Rutherford's Ideas from his experiment = Most of the atom is empty space</p> Signup and view all the answers

<p>Democritus = Atoms are indivisible Rutherford = Empty space in atoms Chadwick = Particles with no charge Bohr = Electrons occupy orbitals</p> Signup and view all the answers

<p>400 BC = Indivisible matter concept 1904 = Plum pudding model introduction 1911 = Nucleus discovery 2022 = Modern nuclear model</p> Signup and view all the answers

<p>Dalton = Atomic theory development Thompson = Discovery of electrons Rutherford = Nucleus location Chadwick = Identifying neutron role</p> Signup and view all the answers

Greek philosopher Democritus proposed that all matter is made up of tiny, indivisible particles called atoms. This idea marked the beginning of the concept of atoms.

John Dalton extended the atom concept in the early 19th century. He proposed that atoms were solid, spherical like tiny balls, similar to snooker balls.

J.J. Thomson suggested the 'plum pudding model'. He proposed atoms were like a positively charged sphere (the pudding) with negatively charged electrons embedded within (the plums).

Rutherford's gold foil experiment revealed that the atom is mostly empty space. It showed that the positive charge is concentrated in a tiny, dense region called the nucleus.

Niels Bohr proposed that electrons in an atom occupy specific energy levels or shells, circling the nucleus. He calculated their orbits and energies.

The idea that all matter is made up of tiny, indivisible particles called atoms.

In 1803, John Dalton proposed that atoms were solid spheres, much like snooker balls.

J.J. Thomson suggested a positively charged sphere with negatively charged electrons embedded within, like plums in a pudding.

Rutherford's experiment with gold foil and alpha particles showed that the atom is mostly empty space, with a positively charged nucleus at the center.

Niels Bohr proposed that electrons occupy specific energy levels or shells, orbiting the nucleus.

A tiny, dense region at the center of an atom where protons and neutrons are located.

Negatively charged particles that orbit the nucleus of an atom in specific energy levels called shells.

They are neutral particles found in the nucleus of an atom, contributing to the mass of the atom.

Rutherford's experiment using gold foil and alpha particles revealed that: (1) An atom is mostly empty space. (2) The positively charged nucleus is at the center.

The idea that atoms are indivisible particles was first proposed by Greek philosopher Democritus.