ATOMIC STRUCTURE

Dalton’s Atomic Theory Objective: Identify the main features of Dalton’s Atomic Theory Each element is made up of tiny, individual particles called atoms. Atoms are indivisible; they cannot be created or destroyed. All atoms of a given element are identical. Atoms of one element are different from those of any other element. Atoms of two different elements have different masses. Atoms of different elements may combine in the ratio of small, whole numbers to form compounds. Chemical reactions occur when atoms are separated, joined, or rearranged.

Subatomic Particles Objective: Identify the three major subatomic particles by charge, relative mass and location in the atom. Subatomic Particle Symbol Charge Mass (grams) Relative Mass (amu) Location Discovered Electron e- 1- 9.109 x 10-28 Outside Nucleus 1897 by Thompson Proton p+ 1+ 1.673 x 10-24 1 Inside 1919 by Rutherford Neutron n° 1.675 x 10-24 1932 by Chadwick

J.J. Thompson’s Experiments Objective: Describe and/or interpret the Thompson cathode ray experiments.

Millikan’s Oil Drop Experiment Mass and Charge of the electron Knowing the electron’s charge ( 1.602 x 10-19 coulombs) and using the known charge-to-mass ratio, calculate mass of electron.

Ernest Rutherford’s Experiments Objective: Describe and/or interpret the Rutherford scattering experiments and the nuclear model of the atom.

The Nuclear Model of the Atom Every atom contains an extremely small, extremely dense nucleus. All of the positive charge and nearly all of the mass of the atom are concentrated in the nucleus. The nucleus is surrounded by a much larger volume of nearly empty space that makes up the rest of the atom. The space outside the nucleus is very thinly, randomly populated by electrons, the total charge of which exactly balances the positive charge of the nucleus.

Distinguishing Between Atoms Objectives: - Explain how the atomic number identifies an element - Explain what isotopes of an element are and how they differ. - Explain what an ion is and what information it gives about an element. - Using Isotope Notation, given one of the following, state the others: (a) nuclear symbol; (b) number of protons, neutrons, and electrons; (c) atomic number, mass number and charge. Isotope Notation (Nuclear Symbol) Sy mass # (protons + neutrons) A charge difference between protons and electrons atomic # (protons) Z

Barium 54 Oxygen 10 82 206 Zinc-66 Name of Element Elemental Symbol Atomic Number Z Numberof Protons Number of Neutrons Mass A Number of Electrons Nuclear Symbol Isotope Name Barium 54 Oxygen 10 82 206 Zinc-66