Valence Electrons LITHIUM ATOM HELIUM ATOM Lithium has one valence electron Helium has two valence electrons
Oxidation Numbers 1+ + 3+ 4+ 3- - 1-0 Transistion metals - variable oxidation numbers Oxidation number corresponds to the need for an atom to gain or lose electrons.
1.. Writing a Chemical Formula Write the formula for a compound that is made of iron (III) and oxygen. Find the oxidation numbers of each element in the compound. 3 The oxidation number of iron (III) is 3+. Its formula is Fe +. Oxygen has an oxidation number of -.Its formula is 0. - Determine the ratios of each element and write the chemical formula. 3+ 3+ + - - - If you have two iron (III) ions for every three oxygen ions, what happens? (3+) added to 3(-) is equal to 0. This means that three iron (III) ions bond with two oxygen ions to get a neutral compound. The formula for a compound of iron (III) and oxygen is Fe 0. 3 An easy way to write a chemical formula: Fe 3+ - O 3 = = 0 Fe O 3
What does a chemical formula tell you? lithium nitrate LiNO 3 1. Number and type of atoms 1 lithium atom 1 nitrogen atom 3 oxygen atoms. Type of ions 3. Formula mass Li 3 + NO 3-6.9 14.0 16.0 16.0 16.0 Formula mass = (6.9) + (14.0) + (3 x 16.0) = 68.9
Formula Mass of a Compound What is the formula mass of calcium carbonate? Write the chemical formula for the compound. calcium: Ca + carbonate: CO Chemical formula: CaCO List the atoms, number of each atom, and atomic mass of each atom. atom Ca C 40.08 Add up the values for each type of atom to calculate the molecular mass. 3-3 1.01 + + 16.00 1 Ca atom 1 C atom 3 O atoms number 1 1 O 3 atomic mass 40.08 1.01 16.00 16.00 40.08 1.01 48.00 16.00 total mass (number x atomic mass) 100.09 The molecular mass of calcium carbonate is 100.09.
Predicting the Products of a Reaction Copper chloride solution reacts with zinc metal to produce what? oxidation numbers + + (s) CuCl compound CuCl Cu (aq) + AX + CuCl (aq) B element Cl? BX + A compound single displacement + Zn (s) Zn (s) Zn Cl Zn + Zn ZnCl + Balanced! (aq) + + element Cu Cu (s) 1. Look up oxidation numbers of elements in compound.. Write the chemical formulas for the reactants. 3. Identify the type of reaction. 4. Predict the products. Write chemical formulas for products. 5. Balance equation.
Balancing Chemical Equations 1. Write the chemical equation. Hydrogen Carbon Oxygen Chlorine Calcium Hydrogen Carbon Oxygen Chlorine Calcium Reactants HCl CaCO 3 HCl + CaCO 3 Reactants CaCl Products CO + + +. Count the number of each type of atom on both sides. H O CaCl + CO + H O Products Missing a Hydrogen atom and a Chlorine atom on the Reactant side. These can only be added as HCl molecule
Balancing Chemical Equations 3. Add coefficients to balance the equation. Hydrogen Carbon Oxygen Chlorine Calcium Reactants Products HCl CaCO 3 CaCl CO + + + H O HCl + CaCO 3 CaCl + CO + H O Hydrogen Carbon Oxygen Chlorine Calcium Reactants Add Products
coefficient coefficient Chemical Formulas Coefficients and Subscripts tells you how many of each type of reactant or product in the reaction A coefficient of in front of methane: CH 4 CH 4 subscript subscript tells you the number of each type of atom in the substance gives you... xch 4 x 1 C = C x 4 H = 8 H carbon atoms and 8 hydrogen atoms enough carbon and hydrogen atoms to make molecules of methane
The Types of Reactions Type General equation Example addition A + B AB H + O H O decomposition AB A + B NaHCO H + NaCO singledisplacement doubledisplacement AX + B BX + A Fe + CuCl FeCl + Cu AB + CD AD + CB Pb(NO ) + KI PbI + KNO carbon combustion compound + O CO + H O C H O + 6O 6CO + 6H O 3 6 1 6 3 3 3
Fission Fission can be started when a neutron bombards a nucleus. A chain reaction results. A B C ENERGY Atom # Atom # Step A A free neutron bombards a nucleus. A B C ENERGY Atom # Step B The nucleus splits. Atom #1 Atom #1 Atom #1 Legend = neutron = nucleus Atom #3 Atom #3 A B Atom #3 C ENERGY Step C The splitting nucleus releases more neutrons. These neutrons bombard other nuclei.
Fusion In fusion, light nuclei are fused into heavier nuclei, releasing a lot of energy. N P N P N P N N P + N + ENERGY SUN The fusion of hydrogen-3 (1 proton + neutrons) with hydogen- (1 proton + 1 neutron) produces a helium nucleus, a neutron, and energy.
- Electron + Proton Neutron Protons Neutrons Nuclear Decay Alpha decay Beta decay Gamma decay - Gamma ray Decrease by Increase by 1 Unchanged Decrease by Decrease by 1 Unchanged What is released? An alpha particle and energy 9P An electron and energy 6P A gamma ray (high energy electromagnetic radiation) 146N 8N 38 9 U 14 6 C beta decay beta decay 34 90P 144N + P N 4 90 Th He 7P 7N + + 14 e 7 N
Carbon Reactions What connections do you see between combustion and photosynthesis? Combustion of fuel EMISSIONS AIR FUEL O N CO CO NO NO H O Water and carbon dioxide are reactants in photosynthesis. CO O H O C 6 H 1 O 6 Glucose and oxygen are products in photosynthesis.
How Trees Help the Environment What can 1 acre of trees do every day? SO 6 lbs O SUN CO 100 lbs CO 0.5 lbs Particulates 48 lbs NO 9 lbs
Solar radiation Global Warming Atmosphere Global warming gases CO CH N O 4 Earth Some of the solar radiation that reaches Earth is absorbed by its surface, and some is reflected and exits the atmosphere. However, heat that builds up within the Earth's atmosphere is trapped by global warming gases. The main global warming gases are carbon dioxide (CO ), methane, (CH ) 4 and nitrous oxide (N O).