Unit 4: Chemistry

1. Unit 4: Chemistry • UNIT 4 • STANDARDS: • STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4 • LESSON 1

2. Solid Liquid Gas Plasma Definite shape Definite Volume. Crystalline structure Definite volume, NO definite shape. Takes shape of container No definite shape, No definite volume. Has volume and shape of container. Temps of 5000oC Ionized gases Found in stars, or plasma furnaces States of Matter

3. Melting Freezing Evaporation Condensation Sublimation Solid to liquid. + Heat Liquid to Solid. - Heat Liquid to Gas. + Heat Gas to Liquid. - Heat Solid to Gas. + Heat Change of State You must be able to identify and give examples

4. Element Examples Hydrogen Helium Gold Lead Xenon A substance that cannot be broken down into simpler substances by physical or chemical means. There are 92 naturally occurring elements Basic Chemistry Terms

5. What is an atom? An atom is the smallest part of an element that has all of the particles of the element. Atoms

6. Democritus Greece 460 - 370 B.C World composed of 2 things Empty Space Tiny particles called atomos The word atomos in Greek means “invisible” Early Atomic Theory

7. Atomic Theory Greece 384-322 B.C. Came AFTER Democritus Believed all mater was continuous and composed of only one material The material of all matter was hyle (the essence) This theory was accepted until the 17th century Aristotle

8. Law of Conservation of Mass Observed chemical reactions in a closed container (system) The Law of Conservation of mass states, “matter can neither be created nor destroyed” and the mass of the reactants must equal the mass of the products. Antoine Lavoisier (1743-1794)

9. J.J. Thompson 1856-1940 Performed experiments to determine the structure or charged parts of the atom. Used a cathode-ray tube to determine that the atom was composed of mainly empty space Credited with the discovery of the electron. Determining the Atomic Parts

10. “Oil-Drop” experiment With a simple experiment was able to detemine the “relative” charge of the electron Measured the force of a tiny charged droplet of oil suspended against gravity between two electrodes (+ and -) Robert Millikan (1868-1953)

11. “Gold Foil” Experiment Lead to Modern Day Model of the Atom Shot a cathode ray into a gold foil and noticed a deflection of the beam Deduced there was something in the atom that was deflecting the beam Called it a nucleus Nucleus orbited by electrons Ernest Rutherford (1871-1937)

12. Atomic Model Represents the overall structure of the atom Nucleus in Center containing protons and neutrons Electrons make up the cloud around the nucleus and have defined arrangements Rutherford-Bohr Model

13. Nucleus Electron Cloud Center part of the atom Contains the majority of the atom’s mass Contains the electrons Divided into energy levels Involved in chemical bonding Parts of the Atom Summary

14. Proton Neutron Electron Positive charge Counts for atomic number Part of atomic mass Neutral Charge Part of atomic mass Negative charge Negligible mass Equal to protons to give neutral charge of element Subatomic Particles Review

15. Element Symbol Atomic Number Atomic Mass See previous defn. Shorthand way of representing element Number of protons present in the nucleus Sum of protons and neutrons in the nucleus Understanding the Element

16. Example of typical Element Identify each part of the picture above (A, B, C, D)

17. The Periodic Table Family Number P E R I O D

18. Student Periodic lab • Stop and perform the simple periodic table lab. This is an in class assignment. • Overall Concept: • Atoms are arranged in families (vertical) based on valence electrons and thus how they react. • Each period (across) represents a different energy level. Remember only the valence electrons react.

19. What is an Energy Level The area of an atom where an electron is likely to be found. Cannot give exact location of the electron Multiple Electrons are distributed over multiple energy levels Energy Levels

20. Look at the periodic table as we discuss energy levels Always remember you start in First grade, meet the requirements and move to second. BUT To get to the second grade, you had to meet the requirements for First grade and then move to second Electrons go to Grade school

21. What are Valence Electrons Bonus: VSPER Valence Shell Electron Pair Electron Repulsion Electrons in the outer most energy level Electrons responsible for forming chemical bonds Valence electrons

22. How do elements combine What is an Ion Elements combine to gather 8 electrons in the outer energy level. Atoms gain or lose electrons to form ion A charged particle Either Positive or negative And the number shall be “8”

23. Lose Electron(s) = Positive Charge Gain Electron(s) = Negative Charge Charge of electron –1 0 – (–1) = +1 Range 0 to +4 Charge of electron –1 0 + (–1) = -1 Range 0 to -4 Getting to 8, Gain or Lose

24. Getting to 8, Gain or Lose 8 7 1 G A I N + L O S E - 6 2 3 5 4 Remember electrons are like pounds… Gaining pounds gives negative self image Losing pounds gives positive self image

26. Lesson Review • Name 3 particles that make up an atom • Define atomic mass • Describe the characteristic of metal ions • How is the periodic table arranged • What happens to size as the atomic number increases • How many electrons does a neutral compound want to have in the outer level