Thirsty for Chemistry?

1. Thirsty for Chemistry? I’ve gotta ask….. Are You……

2. Color Change Demonstration Get a beaker…… No, not that Beaker.

3. Color Change Demonstration “Water” Water + Baking Soda “Fruit Punch” Phenolphthalein (Think CSI) “Milk” Barium Chloride Dichromate + Hydrochloric acid These are toxic, you cannot drink them!!

4. It’s All in the Atom An Intro to Elements and the Periodic Table

5. Elements • Robert Boyle (1627-1691) gave the basis for modern definition of an element • “An element is a pure substance that cannot be chemically broken down into a simpler substance. • Every element has it’s own atomic structure, which we call an atom

6. Parts of an Atom • An atom is made up of 3 types of particles. • 1) The electron (e-) • Has a charge of -1 • Has relatively no mass • Is found in an orbital/shell, around the nucleus of an atom

7. Parts of an Atom • 2) The proton (p+) • Has a charge of +1 • Has a mass of 1 amu • Amu = Atomic Mass Unit • Is found in the nucleus of the atom

8. Parts of an Atom • 3) the neutron (n) • Has NO charge • Has a mass of 1 amu • Is found in the nucleus of the atom

9. Bohr Diagram of the Atom • Niels Bohr was a Danish physicist. • He proposed a model of an atom where: • protons and neutrons are located in the centre of the atom (nucleus) • and the electrons move around the nucleus in orbits called shells

10. Bohr Diagrams • Each shell can hold a specific number of electrons. • K-shell is the first shell and can hold 2 electrons • L-shell is the second shell and can hold 8 electrons • M-shell is the third shell and can hold 8 electrons • Remember: Neutral atoms always have the same number of electrons as protons (charges cancel)

11. + + + + + Bohr Diagrams • E.g-a boron atom has 5 p+, 5 e-, and 6 n. Draw the Bohr diagram:

12. + + + + Bohr Diagrams • A beryillium atom has 4 p+, 4 e-, and 5n. Draw it:

13. Bohr Diagram • A phosphorus atom has 15 p+, 15 e-, and 16 n. Draw it: 15 p+ 16 n

14. Reading from the Periodic Table • Each element in the periodic table is represented by a symbol. • Every symbol has an upper case letter. • Some symbols have two letters. • The first is upper case • The second is lower case (e.g. Ca is calcium)

15. E.g. • C is the symbol for carbon • Cl is the symbol for chlorine • Cu is the symbol for copper

16. Atomic Number • Is the number of protons that an atom has. • Each element has a unique atomic number. • Every element is arranged according to atomic number on the periodic table. • Atomic number = # of p+

17. Atomic Number Is found in the top left-hand corner

18. Atomic Mass • Is the mass of the atom in amu. • Since each proton has a mass of 1 amu, and each neutron has a mass of 1 amu, then the atomic mass is equal to the number of protons and neutrons. • Atomic mass = # protons + # neutrons

19. Atomic Mass • E.g. Nitrogen has 7 p+ and 7 n. • So, atomic mass = 7 + 7 = 14 amu Is found under the symbol.

20. On Your Periodic Table

21. Assignment • Use your periodic table to fill in the table on page 4. We’ll do a few together.