Bell Ringer 9-24-09 We mentioned the Periodic Table of __________ yesterday. A(an) _______ is the smallest part of an element. An atom has four parts: the nucleus, ________, electrons, and neutrons. Tell me what kind of charge each part has: Proton ________ Electron _________ Neutron _________

Review of the Periodic Table of Elements Goals for Today… Review of the Atom Review of the Periodic Table of Elements

Periodic Table of Elements

Dynamic Periodic Table

Draw the Element Square List…. Atomic Number _______ # of Protons _______ # of Electrons ________ Symbol _______ Name ________ Atomic Mass _________ Mass Number (Atomic Mass rounded) ________ # of Neutrons (Mass # - Atomic #)________ Create the atom

Chapter 4 Section 1 ( Part 2) Atomic Models

The first people to contribute to the development of atoms were Democritus and Dalton.

Democritus 430 B.C.- He used the word “atomos” (uncuttable) to describe the smallest possible piece of matter. All matter was made up of small particles called atoms.

Points of Dalton's Theory: The Dalton Model: 1803- John Dalton - English chemist that proposed first atomic theory Points of Dalton's Theory: All elements are composed of indivisible particles. Atoms of the same element are exactly alike. Atoms of different elements are different. Compounds are formed by joining atoms of two or more elements.

Thomson and Rutherford Discovery 1897- J.J. Thomson discovered that atoms have negatively charged particles. (Electrons) 1911-Rutherford discovered that atoms have a positive charge and that the positive charge is located in the center of the atom called the nucleus.

1913- Niels Bohr- showed that electrons could only have specific amounts of energy, causing them to move in certain orbits. 1920s- Scientists determined that electrons do not move in orbits but are moving in a cloud-like region known as the electron cloud

1932- James Chadwick discovered that there was another particle in the nucleus with the same mass as a proton but neutral in charge

Atomic Model Video