History of Atomic Theory PDF

THIS REVIEWER SHOULD NOT BE SHARED TO ANYONE ⚠️ THANK YOU! HISTORY OF ATOMIC THEORY THE HISTORY OF ATOMIC THEORY What is an atom? > The smallest particle of an element. > The smallest amount of a substance that can take pan In any chemical reaction. DEMOCRITUS > He is a Greek Phil...

THIS REVIEWER SHOULD NOT BE SHARED TO ANYONE ⚠️ THANK YOU! HISTORY OF ATOMIC THEORY THE HISTORY OF ATOMIC THEORY What is an atom? > The smallest particle of an element. > The smallest amount of a substance that can take pan In any chemical reaction. DEMOCRITUS > He is a Greek Philosopher who began to search for a description of matter. > He named the smallest piece of matter: "ATOMOS" meaning "not to be cut". > They were small, hard particles that were all made of the same material but were different shapes and sizes. > This piece is indivisible. JOHN DALTON > In the early 1800s.John Dalton (English Chemist) performed a number of experiments that eventually led to the acceptance of the idea of atoms. > He deduced that all elements are composed of atoms. > Atoms of the same element are exactly alike. > Atoms of different elements are different. > Compounds are formed by the Joining of atoms of two or more elements. JOSEPH JOHN THOMSON > In 1897, J.J. Thomson, an English Scientist, provided the first hint that an atom is made of even smaller particles. > Introduced the idea about the negatively charged particle called "electron". PLUM PUDDING ATOMIC MODEL > He proposed a model of the atom that is sometimes called "Plum Pudding" Model. > Atoms were made from positively charged substance with negatively charged electrons scattered about, like raisins in a pudding. ERNEST RUTHERFORD > In 1908, E Rutherford, an English Physicist, was hand at work on an experiment. > He reasoned that all atoms that are positively charged particles were contained in the nucleus. Negatively charged particles were scattered outside the nucleus around the atom's edge. > He made "Alpha Scattering Experiment" NIELS BOHR > In 1913, N. Bohr. a Danish Scientist, proposed an improvement. > He placed each electron in a specific energy level. Electrons move in definite orbits around the nucleus, much like planet circles the sun (solar system). These orbits, or energy levels are located at certain distances from the nucleus. ARNOLD SOMMERFELD > A. Sommerfeld, a brilliant German Physicist, modified Niels Bohr's atomic theory to include elliptical orbits. > Electrons are moving around the nucleus. > Assumed that orbils doesn't have to be spherical but can also be elliptical. > Electrons are moving around the nucleus. > Assumed that orbits don't have to be spherical but can also be elliptical. ERWIN SCHRODINGER > E. Schrodinger, Physicist and a Biologist, was considered the Father of Quantum Mechanics > Today's atomic model is based on the principles of wave mechanics. > Electrons do not move around an atom in a definite path like the planets around the sun. > A space in which electrons are likely to be found. > Electrons whirl about the nucleus billions of times in one second. > They are not moving around in random patterns. > Location of electrons depends upon how much energy the electron has. Electron Configuration > Is the arrangement of electrons in energy levels around an atomic nucleus. > It is the shorthand representation on how each electron is arranged among the orbitals, levels, and sublevels. Ex: ¹⁰Ne = 1s² 2s² 2p⁶ Electron Configurations > Electron configurations tell us in which orbitals the electrons for an element are located. Three rules: - electrons fill orbitals starting with lowest n and moving upwards(Aufbau):. - no two electrons can fill one orbital with the same spin (Pauli); - electrons fill each orbital singly before any orbital gets a second electron (Hund's rule). S - Sharp P - Principle D - Defuse F - Fundamental Sublevels & Orbitals > Sublevels are divided into orbitals increasing odd numbers, so s has 1. phas 3d has 5. has 7) > Each orbital can contain 2 electrons