Atomic Structure Scale of the Universe

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Aristotle 384 -322 BC Describe the plum pudding model Proposed that all matter is made of five elements: Fire (hot and dry) Earth (cold and dry) Air (hot and wet) Water (cold and wet) Aether (divine substance that makes up the heavenly spheres and heavenly bodies (stars & planets) Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Matter composed of tiny indivisible particles. Demokritos 460-370 BC Matter composed of tiny indivisible particles. Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

John Dalton 1766-1844 Describe the plum pudding model All matter is made of atoms, and atoms are indestructible and cannot be broken down into pieces All the atoms of a particular element are identical to each other and different from the atoms of other elements Atoms are rearranged in a chemical reaction Compounds are formed when two or more different kinds of atoms join together Atoms cannot be divided into smaller particles – they are indivisible. There are spaces between atoms. Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

J.J. Thomson 1856-1940 Development of the plum pudding model Electrons (like negative ‘plums’) embedded in a ‘pudding’ of positive matter, with the negative charge of the electrons balanced by the positive charge of the ‘pudding’ Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

The Plum Pudding Model Describe the plum pudding model Atoms are neutral so are made of equal positive and negative material. Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Gold Foil Experiment Alpha particles (which are small positive particles) are fired at a gold leaf 𝛼 The gold leaf is surrounded by a detector Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Gold Foil Experiment Geiger and Marsden Rutherford If the gold atoms are like a plum pudding then all the particles would pass straight through it like a bullet through sponge Geiger and Marsden Rutherford 1871 - 1937 Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Gold Foil Experiment Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Results 1. Most particles when straight through the gold foil 2. A small number were bounced straight back at the detector 3. Some of the particles were deflected at large angles Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Structure of the Atom 1. Most particles went straight through the gold foil Most of the atom is made of empty space 2. A small number were bounced straight back at the detector The mass of an atom is mostly concentrated in the centre in a dense nucleus 3. Some of the particles were deflected at large angles The centre mass is positively charged and repels the alpha particles when they pass nearby Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure This was completely unexpected and meant that the current theory of atomic structure was wrong. “It was quite the most incredible event that ever happened in my life. It was as if you fired a 15 inch shell at a piece of tissue paper and it came back and hit you.” Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Positive nucleus (most of the mass of the atom) Negative part of the atom Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

James Chadwick 1891-1974 Discovered the neutron in the nucleus Neutron – subatomic particle. Same mass as a proton but zero charge. Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Niels Bohr 1885-1962 Electrons circle the nucleus at high speed Electrons are kept in certain energy levels in a stable formation around the atomic nucleus. Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom

Atomic Structure Describe the plum pudding model Describe and explain the results of the gold leaf experiment Describe the structure of the atom