Chapter 4 Atomic Structure 4.2 Structure of the Nuclear Atom 4.1 Defining the Atom 4.2 Structure of the Nuclear Atom 4.3 Distinguishing Among Atoms Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
https://www.youtube.com/watch?v=xazQRcSCRaY Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Early Models of the Atom Democritus Greek philosopher (460 BC –370 BC) Among first to suggest existence of atoms. Reasoned atoms were indivisible & indestructible Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Early Models of the Atom Dalton English chemist & school teacher 1766 – 1864 Used experimental methods to transform Democritus’ ideas into scientific theory Studied ratios of how elements combine in chemical reactions Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Early Models of the Atom Dalton’s Atomic Theory All elements are composed of tiny indivisible particles called atoms. Atoms of element A Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Early Models of the Atom Dalton’s Atomic Theory Atoms of the same element are identical. Atoms of element A Atoms of element B Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Early Models of the Atom Dalton’s Atomic Theory Atoms of different elements can chemically combine in simple whole-number ratios to form compounds.(Law of Definite proportions) Mixture of atoms of elements A and B Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Early Models of the Atom Dalton’s Atomic Theory In chemical reactions atoms are separated, combined, or rearranged. (but cannot be destroyed) Compound made by chemically combining atoms of elements A and B Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
In 1897, J. J. Thomson discovered the electron. Subatomic Particles Electrons In 1897, J. J. Thomson discovered the electron. https://www.youtube.com/watch?v=XU8nMKkzbT8 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Thomson’s atomic model Plum Pudding Model Thomson’s atomic model Electrons stuck in a lump of positive charge, similar to raisins stuck in dough. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Additional Discoveries 1886 – Goldstein identified protons Subatomic Particles Additional Discoveries 1886 – Goldstein identified protons 1909 - Millikan determined electron’s charge. 1932 – Chadwick confirmed existence of the neutron Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Rutherford’s Gold-Foil Experiment The Atomic Nucleus Rutherford’s Gold-Foil Experiment Narrow beam of alpha particles was directed at a thin sheet of gold. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Rutherford’s Gold-Foil Experiment The Atomic Nucleus Rutherford’s Gold-Foil Experiment Some alpha particles bounced off the gold foil https://www.youtube.com/watch?v=5pZj0u_XMbc Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
The Rutherford Atomic Model Protons and neutrons are in the nucleus The Atomic Nucleus The Rutherford Atomic Model Protons and neutrons are in the nucleus Electrons distributed around nucleus and occupy almost all of the volume of the atom Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Bohr model 1915 Protons and Neutrons are in the nucleus Electrons are outside the nucleus in orbitals Electrons can move from one orbital to another, and release energy as electromagnetic radiation. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Electron cloud Model Electrons are in clouds (Schrodinger) Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
END OF 4.2 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.