The document discusses the history and structure of the atom. It describes how early Greek philosophers proposed early models of matter as earth, fire, air and water. Democritus proposed that all matter is made of indivisible atoms. John Dalton's model proposed atoms as spheres and that elements are made of unique unchanging atoms. J.J. Thompson discovered atoms have internal structure. Rutherford determined the atom's mass is concentrated in a tiny nucleus. Bohr proposed electrons orbit the dense nucleus. The document outlines the subatomic particles of protons, neutrons, and electrons and how they differ in mass and charge. It describes atomic structure in terms of shells and the terminology used to describe atomic number, weight, isotopes and charge

1. Atomic Structure

2. I. Electrical Charges Repel Same charges (+ to +) or (- to -) Attraction Opposites (+ to -)

3. II. History of Chemistry Early Greek Elements Earth, Fire, Air, Water

4. II. History of Chemistry Democritus (~400 BC) Smallest matter is an atom

5. II. History of Chemistry Alchemists (Middle Ages) Trying to make Gold

6. II. History of Chemistry John Dalton (1808) Atom are small spheres (marble) Elements made of unchangeable atoms Compound have specific ratios of atoms

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9. II. History of Chemistry J. J. Thompson (1897) Atoms have parts

10. II. History of Chemistry Earnest Rutherford (1911) Atom’s mass in the center (1:10,000)

11. II. History of Chemistry Neil Bohr (1913) Negative charges orbit dense center

12. III. Structure of the Atom Particles inside the atom Proton Neutron Electron 75

13. III. Structure of the Atom How are they different? (1.67 x 10-24g) 1 +1 1 0 0.0005 -1

14. III. Structure of the Atom Shells e C. Location inside the atom Nucleus p & n 75

15. III. Structure of the Atom D. Terminology Atomic Number = # p Element name On table: Top of each box By hand: Bottom Left Atomic Weight = # p + # n On table: Bottom of each box By hand: Top Left

16. III. Structure of the Atom D. Terminology Atomic Weight = # p + # n Every new weight = Isotope 78

17. III. Structure of the Atom +2 11 C 6 D. Terminology Charge Determined by amount of electrons p – e = Charge Written in top right corner On Table: ALWAYS NO CHARGE