1. Atoms and Moles

2.  All matter is made of atoms  Law of definite proportions  Water is 88.8 % oxygen and 11.2 % hydrogen  Law of conservation of mass  Mass cannot be created or destroyed  Law of multiple proportions  CO, CO 2 / C 6 H 12 O 6, C 12 H 22 O 11 / H 2 O, H 2 O 2

3. 1. All matter is made of extremely small particles called atoms. 2. Atoms of a given element are identical in their properties. 3. Atoms cannot be created, destroyed, or subdivided. 4. Atoms of different elements combine in simple whole-number ratios to form compounds. 5. In chemical reactions, atoms are combined, separated, or rearranged.

4. Electrons were discovered in a Cathode Ray Tube Electrons are very small particles that have a negative charge

5. “Plum pudding” model Electrons were embedded in a positively charged ball of matter

6. Rutherford shot a stream of positive particles at a piece of gold foil and expected the particles to go right through the atoms of gold.

7. He expected most of the particles to go straight through but some of the particles bounced straight back. Something very dense and positively charged had to be the reason it bounced back.

8. Old model New and improved model The atom is very large compared to the size of the nucleus

9. Protons are positively charged particles Neutrons have no charge - neutral

10.  Atomic number = number of protons  Protons = electrons  Atomic mass = protons + neutrons  Isotope – atoms of a certain element that have a different mass because it has a different number of neutrons.

11.  Electrons are found in 3-dimensional spaces around the nucleus called orbitals.  We use 4 quantum numbers to tell: 1. The distance from the nucleus 2. The shape of the orbital 3. The relationship of the orbitals with the x,y,z axes 4. The spin of the electrons

12.  Indicates the main energy level  Values = 1 – 7  This shows how far the orbital is from the nucleus.

13.  Indicates the shape of the orbital  4 shapes  s, p, d, f

16.  Indicates the orientation of the orbitals on the x, y, and z axes.  How many orbitals there are  s – 1  p – 3  d – 5  f – 7

17.  Electrons spin in opposite direction  (+1/2, -1/2)  2 electrons can fit in each orbital

19.  Oxygen – 8 electrons  1s 2 2s 2 2p 4  Sodium – 11 electrons  1s 2 2s 2 2p 6 3s 1  Argon – 18 electrons  1s 2 2s 2 2p 6 3s 2 3p 6  Arsenic – 33 electrons  1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 3

20.  1 mole of any substance has 6.02 x 10 23 atoms  (Avogadro’s number)  1 mole of any substance is equal to it’s mass on the periodic table in grams.  (Molar mass)