2.  ATOM – smallest piece of an element

3.  Nucleus › Very dense, almost all the mass of the atom, but very small › Protons – positively charged, one AMU › Neutrons – no charge (neutral), one AMU  Energy levels › Electrons – e - -negatively charged, very small › First energy level – only two electrons › Later energy levels – eight electrons

4. Element Name HydrogenHeliumLithiumsodium # protons12311 # electrons 12311 # neutrons 02311 Atomic Number 12311 Atomic Mass Number 14622

5.  ATOMS – smallest piece of an element › GROUND STATE – overall zero charge › Equal numbers of protons and electrons  IONS – atoms with charges! › Electrons have been stolen… the imbalance of protons (positive) and electrons (negative) results in a charged particle

6.  Chlorine has 17 protons and 17 electrons  The chlor ide ion stole an electron from another atom… it now has 17 protons and 18 electrons  It has a negative charge because it has more electrons than protons

7. # protons# electrons Charge (protons – electrons) Cation, anion or neutral atom? SymbolName 440NeutralBeBeryllium 422+CationBe 2+ Beryllium 17 0NeutralClChlorine 17181-AnionCl - Chloride 770NeutralNNitrogen 7103-AnionN 3- Nitride

8.  How can we determine what charge an ion will have?  The OCTET rule… atoms want to be like noble gases and have eight electrons in their valence (outer) energy level  We can predict charges with groups of the periodic table

10.  Groups of atoms that share electrons with each other, but then steal more! › Or electrons they were sharing were stolen from them… › Names do NOT end in -ide

11.  Ions with opposite charges are attracted to each other like magnets › We call this attraction an ionic bond › Compounds formed by ionic bonds are called ionic compounds  Charges are shown with little numbers up = superscript… K 1+  Numbers of ions in the formula are shown with little numbers down = subscript… O 2

12.  We balance the charges of the ions › Potassium fluoride  K 1+ + F 1- -> KF › Lithium oxide  Li 1+ + O 2- -> Li 2 O › Magnesium bromide  Mg 2+ + Br 1- -> MgBr 2

13. IONIC CompoundsMOLECULAR Compounds Steal electrons = ionic bondShare electrons = covalent bond Ions and polyatomic ionsAtoms Metal + Non-metalNon-metal + Non-metal Formula unit – balanced chargesMolecule – numbers of atoms Second element ends in –ide NO prefixesYES prefixes Na 2 O – sodium oxide MgCl 2 – magnesium chloride KOH – potassium hydroxide CO – carbon monoxide N 2 O – dinitrogen oxide Si 3 N 4 – trisilicon tetranitride

14.  Naming acids is similar to naming ionic compounds… › Cl - is chloride  HCl is hydrochloric acid › SO 4 2- is sulfate  H 2 SO 4 is sulfuric acid

15.  Not this mole…

16.  This mole… 6.02 x 10 23

17.  Amedeo Avogadro, 1811 - proposed that the volume of a gas at a given pressure and temperature is proportional to the number of molecules or atoms of the gas, no matter how large or small each atom or molecule is › In other words, more molecules = more volume

18.  Many scientists… Jean Perrin, JJ Loschmidt, Robert Millikan, Michael Faraday… over many years were involved in experiments that led to the determination of the number of molecules  In 1906, Jean Perrin proposed naming the number in honor of Avogadro… › Avogadro’s number = 6.02 x 10 23

19.  One mole of a substance has a gram mass equal to the atomic mass (AMU)of that substance › Carbon-12 has a mass of 12 AMU  One mole of Carbon-12 has a mass of 12 g › One molecule of H 2 O has a mass of 18 AMU  One mole of H 2 O has a mass of 18 g  So if you have 18 g water, you have… 6.02 x 10 23 molecules of water

20. Substance Atomic mass (AMU) Molar Mass (kg) Total mass# moles# molecules Helium4.0 AMU4.0 g 1 mol6.02 x 10 23 Helium4.0 AMU4.0 g8.0 g2 mol 12.04 x 10 23 = 1.20 x 10 24 Helium4.0 AMU4.0 g2.0 g½ mol3.01 x 10 23 CO 2 C = 12.0 AMU O = 16.0 AMU +O = 16.0 AMU 44.0 AMU 44.0 g 1 mol6.02 x 10 23 CO 2 44.0 AMU44.0 g11.0 g¼ mol1.51 x 10 23 NaCl Na = 23.0 AMU + Cl =35.5 AMU 58.5 AMU 58.5 g175.5 g3 mol 18.06 x 10 23 = 1.81 x 10 24

21.  Switching between units › Atomic mass molar mass moles › Kilometers Meters Centimeters Unit conversion factors 100 m = __?__ cm 100 m x 100 cm = 10,000 cm 1 m

22.  1 hour = ______ seconds 1 hr x 60 min x 60 sec = 3600 seconds 1 hr 1 min  1 year = ______ seconds 1 yr x 365 days x 24 hr x 60 min x 60 sec = 31,536,000 seconds 1 yr 1 day 1 hr 1 min  60 miles/hr = ________ feet/second 60 mi x 5280 ft x 1 hr x 1 min = 88 feet/sec 1 hr 1 mi 60 min 60 sec