Unit 1: Chemistry. Mr. Huang Science 10. This note package belongs to

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1 Mr. Huang Science 10 Unit 1: Chemistry 1. Atomic Theory 2. Periodic Table 3. Isotopes and Radioactive Particles 4. Half-life 5. Chemical Formula for Ionic Compounds 6. Chemical Formula for Molecular Compounds 7. Law of Conservation of Mass 8. Balancing Chemical Reaction 9. Types of Reactions 10. Ionic vs. Covalent Bonding 11. Acid,Base,Salt,pH 12. Collision Theory and Reaction Rates This note package belongs to

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3 Mr. Huang Science 10 Atomic Theory [Text Reference: 4.1 Atomic Theory and Bonding] Goal 1: Be able to read and draw a Bohr model of an Atom Chemistry Lesson 1 History of the Atom 1800: John Dalton 1898: J. J. Thompson 1911: Ernest Rutherford 1913: Neils Bohr Bohr Model Although Neils Bohr s model is no longer the correct model of the atom, we still use the Bohr model in our study of how an atom works. It is the simpler way of looking at an atom without going into high level math and calculus. Chemical Symbols on the Periodic Table 1

4 How to Draw Bohr Models of the Element Let s begin our practice with Fluorine. How many protons does it have? How many electrons does it have? Step 1: Label the center of the diagram with the atomic number and symbol for the element Step 2: Determine the number of shells needed. Remembering that 1 st shell can have 2 electrons while the 2 nd and 3 rd shell can have 8 electrons. Step 3: Fill the first shell with 1 set of paired electrons Step 4: Place as many electrons as needed into the second shell (maximum is 8 electrons). Fill each position (top, bottom, left, right) with one electron before pairing them up. Continue on to third shell (maximum 8 electrons) if needed Now let s practice with new more elements: 1) Sulphur 2) Calcium 2

5 Mr. Huang Science 10 Periodic Table [Text Reference: 4.1 Atomic Theory and Bonding] Goal 2: Understand how the periodic table was assembled Goal 3: Describe the properties of elements as grouped on the periodic table Goal 4: Understand the relationships between the subatomic particles of an atom Chemistry Lesson 2 Looking at the Periodic Table Let s look at it with more details. Going Down the Periodic Table: Going Across the Periodic Table: 3

6 Alkali Metals Alkaline Earth Metals Transition Metals Lithium (Li) Sodium (Na) Potassium (K) Rubidium (Rb) Cesium (Cs) Francium (Fr) Beryllium (Be) Magnesium (Mg) Calcium (Ca) Strontium (Sr) Barium (Ba) Radium (Ra) Metals in the middle of the periodic table Halogens Nobel Gases Fluorine (F) Chlorine (Cl) Bromine (Br) Iodine (I) Astatine (At) Helium (He) Neon (Ne) Argon (Ar) Krypton (Kr) Xenon (Xe) Radon (Rn) Using the Periodic Table Symbol # protons # electrons # neutrons Atomic number Atomic mass Charge on nucleus Charge on atom/ion 24 12Mg 39 19K O

7 Mr. Huang Science 10 Isotopes and Radioactive Particles [Text Reference: 7.1 Isotopes and Radioactive Decay] Goal 5: Define and explain what radiation is Goal 6: Define and explain what isotopes are Goal 7: Understand the 3 different types of radioactive decay Chemistry Lesson 3 Radiation We ve often heard of the word radiation in movies or TV shows, but what exactly is radiation? Radiation: There are many forms of radiation. Visible light is a form of radiation. Some radiation are harmful to us, some aren t. Isotopes Once neutrons were discovered, scientists found out that sometimes the would have. This was because these elements differ in the number of. These elements were said to be of one another Isotopes: This is important to our study of radioactivity because certain isotopes of the same element can be or. Hence, we can clarify our previous statement that radiation is a result of unstable isotope to a stable isotope. 5

8 Example: Radioactive Materials Interestingly enough, certain isotopes of elements were found to be radioactive and highly unstable. These particles would undergo radioactive decay, or what we commonly call: Radioactive decay: 1. Alpha Decay Alpha decay occurs when a radioactive atom emits an alpha particle It has 2 and 2, identical to a nucleus 6

9 Example: Write the nuclear equation for the alpha decay of americium Beta Decay Beta decay occurs when a radioactive atom emits an beta particle It has only 1 and is identical to an Example: Write the nuclear equation for the beta decay of cesium Gamma Decay In gamma decay, the nucleus emits light rays These rays are very high in energy Usually, alpha and beta decay leads to a nucleus that would be (excited). This energy is released as gamma ray so that the nucleus would go back to a Example: Write the nuclear equation for the beta decay of boron-12 to an excited nucleus 7

10 Mr. Huang Science 10 Goal 8: Explain the process of half-life Goal 9: Understand how radioactive dating works Half-Life [Text Reference: 7.2 Half-Life] Chemistry Lesson 4 Half-Life Half-life: We learned from the previous class that certain isotopes of elements are radioactive, meaning that they will undergo either alpha, beta, and/or gamma decay. Half-life is the amount of time it takes for of a. Different isotopes and different elements have different half-life s. In other words, certain material than other materials Number of Half-lives Fraction remaining Percent remaining Example: Cesium-124 has a half-life of 31 seconds. A sample of cesium-124 in a laboratory has an initial mass of 20 g a) Calculate the amount of time it will take for the sample to decay to 5 g b) Calculate how much cesium-124 will remain after 93 s 8

11 Decay Series Sometimes the. Then it will undergo in-attempt to become stable. When radioactive nuclei form such a of radioactive decay, we call it a decay series. Observe the following diagram Radioactive Dating Once we know the half-life of a radioactive isotope, we can use this knowledge to., with a half-life of, is often used to date old materials left on Earth. When a living organism dies, no new carbon-14 will enter the organism. As a result, Carbon-14 will begin to decay. By of Carbon-14 remaining in the organism, we can use its half-life to determine how old the organism is..kind of like what we just did! Example: A piece of leather was found to have 12.5% of its original carbon-14 present. Determine the age of the leather using the figure below and by calculations 9

12 Mr. Huang Science 10 Chemical Formula for Ionic Compounds [Text Reference: 4.2 Names and Formulas of Compounds] Goal 10: Know how to name and write chemical formulas for Ionic Compounds Chemistry Lesson 5 A) Writing Formula Ionic Compound: A compound where the first element is a metal followed by a non-metal 1. Example: Write sodium sulfide as its chemical formula Step 1: Determine the symbol of the first element. Step 2: Determine the symbol of the second element. Remember, the ending ide means that the name represents an element on the periodic table. Look for the element with the same beginning to its name. Step 3: Place the two symbols side-by-side in order and write their charge (found from the periodic table) at the top right of each elements symbol. Ignore the + or - at this point. Step 4: Cross over the charges so that the number becomes the subscript Step 5: Reduce the subscripts if they have a common factor and delete all the Example: Write ammonium sulfate as its chemical formula **Notice that ammonium and sulfate are not elements! They are polyatomic ions! It looks hard, but the procedures are the same. Step 1: Determine the symbol of the first part Step 2: Determine the symbol of the second part Step 3: Place a bracket around each polyatomic ion. Use the charge and cross over: Step 4: Reduce the subscripts if they have a common factor. Delete all the 1 and remove brackets if there are no subscripts following them. 10

13 3. Example: Write iron (III) chloride as its chemical formula **Notice that there is a (III) following iron. All transition metals could have more than 1 charge. Iron here, can either be 2+ or 3+. Therefore, the (III) tells us what charge this iron will be! Step 1: Determine the symbol of the first part Step 2: Determine the symbol of the second part Step 3: Place a bracket around each polyatomic ion. Use the charge and cross over: Step 4: Reduce the subscripts if they have a common factor. Delete all the 1 and remove brackets if there are no subscripts following them. Example: Write the formula for these ionic compounds a) copper (II) chloride b) lead (IV) oxide c) aluminum sulphide d) copper (II) hydroxide e) gold (III) sulfate f) aluminum phosphate g) potassium oxide h) calcium nitride i) magnesium phosphide j) ammonium phosphate B) Naming a Formula 1. Example: Write Na2O as its chemical name Step 1: Find the first element on the periodic table Step 2: Find the next element in the compound, but change its ending to ide Step 3: Place the two names in order with a space 11

14 2. Example: Write Cu2O as its chemical name **Cu has two possible charges! Step 1: Uncross the chemical name to figure out the charges of the first element Step 2: Write the first element followed by its charge in Roman numerals in brackets Step 3: The rest is the same 3. Example: Write (NH4)2CO3 as its chemical name **Use your list of polyatomic ions on the back of your periodic table Step 1: Name the first part of the compound Step 2: Name the second part of the compound, but if it is not an element, don t change the ending to ide Step 3: Put the two names together in order Example: Write the formula for these ionic compounds a) Cs2Se b) AgBr c) Al2O3 d) AuN e) SnO2 f) MnS2 g) K2SO4 h) NH4OH i) Sr(ClO3)2 12

15 Mr. Huang Science 10 Chemical Formula for Molecular Cmpds [Text Reference: 4.2 Names and Formulas of Compounds] Chemistry Lesson 6 Goal 11: Know how to name and write chemical formulas for Molecular Compounds A) Writing Chemical Formula Molecular Compound: A compound where the first element is a non-metal followed by a non-metal 1. Example: Write sulfur hexafluoride as its chemical formula Step 1: Look at the first part of the name to identify the element and the number of them you need to include. If there is no prefix, that s the same as mono or one. Step 2: do the same thing for the second part Step 3: Ignore charges. Do not cross over. Just write the numbers as subscripts Here is a list of prefixes Prefix Value Mono 1 Di 2 Tri 3 Tetra 4 Penta 5 Hexa 6 Hepta 7 Octa 8 Nona 9 Deca 10 Example: Write the formula for these molecular compounds a) Boron tribromide b) dinitrogen pentaselenide c) carbon monoxide d) Phosphorous trichloride 13

16 B) Naming Compounds 1. Example: Write CCl4 as its chemical name Step 1: Do not use charges! Step 2: Use prefixes (from the table before) to give the number of each element Step 3: If the first element has mono as its prefix, you can ignore it. Don t forget to change the ending of the second element Example: Write the formula for these molecular compounds a) N2Cl5 b) SO3 c) AsI4 d) XeF6 14

17 Mr. Huang Science 10 Law of Conservation of Mass [Text Reference: 4.3 Chemical Equations] Goal 12: Understand how the Law of Conservation of Mass applies to chemical reactions Chemistry Lesson 7 Reaction 1: Reaction 2: 15

18 Mr. Huang Science 10 Balancing Chemical Reactions [Text Reference: 4.3 Chemical Equations] Goal 13: Balance chemical equations according to the Law of Conservation of Mass Chemistry Lesson 8 Chemical Reactions HCl + Na2CO3 NaCl + H2O + CO2 Law of conservation of Mass states that in a closed system, no atoms will be gained or loss. However, if we try to count the atoms in that chemical equation, we notice that the atoms don t balance out! So, what we will learn now is to balance chemical equations! Example 1: Balance the following equation: HCl + Na2CO3 NaCl + H2O + CO2 Step 1: Write down the number of each element present on each side of the equation. HCl + Na2CO3 NaCl + H2O + CO2 Step 2: Balance one of the elements (REMEMBER THAT YOU MAY ONLY PLACE NUMBERS IN FRONT OF THE CHEMCIAL FORMULA DN THAT YOU MAY NOT CHANGE THE FORMULA) HCl + Na2CO3 NaCl + H2O + CO2 Step 3: Check to see if any other elements are sill unbalanced and if so, balance ONE of them HCl + Na2CO3 NaCl + H2O + CO2 Other Steps: repeat this process as many times as necessary, always changing one at a time until ALL of the elements are balanced. The equation is then balanced and we can all sleep safe knowing that the Law of Conservation of Mass is preserved! 16

19 You Try! Example 2: Fe + CuSO4 Fe2(SO4)3 + Cu Example 3: Al + HCl AlCl3 + H2 Example 4: AlBr3 + K KBr + Al Word Problems Now let s make things a little harder! Now that we are competent in writing chemical formulas and balancing, let s put them together: Write a balance reaction for the following chemical reactions: Example 1: Sodium metal reacts with water to form sodium hydroxide and hydrogen gas Example 2: Zinc metal reacts with copper (II) sulfate to produce zin sulfate and copper metal Example 3: Hydrogen Chloride reacts with barium fluoride to produce hydrogen fluoride and barium chloride 17

20 Type of Reaction Definition General Equation Examples Synthesis Decomposition Single Replacement Double Replacement Combustion Mr. Huang Science 10 Types of Chemical Reactions [Text Reference: 6.1 Types of Chemical Reactions] Goal 14: Explain and describe the different types of chemical reactions Chemistry Lesson 9 18

21 Mr. Huang Science 10 Ionic Vs. Covalent Bonding [Text Reference: 4.1 Atomic Theory and Bonding] Chemistry Lesson 10 Goal 15: Understand how Ionic bonds are formed Goal 16: Understand how covalent bonds are formed Introduction Why do atoms bond with other atoms in the first place? There are 2 ways to achieve this noble objective 1) and form compounds 2) and form compounds Ionic Bonding Ionic bonding involves the formation of and ions. This happens easily for atoms which only have a few electrons to or a few electrons to to obtain a. These ions are then attracted to each other by strong and form compounds. These compounds tend to form as Important: There is NO NaCl molecule. The formula of ionic compounds I just a ratio of the ions which are attracted together. You don t see the individual NaCl molecules. You see a whole network/cube of Na + and Cl - ions. What does MgCl 2 look like: How does the formation of ionic crystals explain the properties of ionic compounds? 19

22 Covalent Bonding Covalent bonding involves the sharing of electrons to form This happens typically for atoms of, for example, and. Eg. Notice once again the noble objective is achieved How does the formation of covalent molecules explain the properties of covalent compounds? 20

23 Mr. Huang Science 10 Acid/Base/Salt/pH [Text Reference: 5.1 Acids and Bases, 5.2 Salts] Goal 17: Be able to classify the different types of compounds Goal 18: Understand the similarities and differences between acids and bases Chemistry Lesson 11 Classifying Compounds Example: Classify the following compounds as Acid, Base, Salt or Covalent Compound a) Na 3PO 4 b) Al(OH) 3 c) Ca(OH) 2 d) H 3PO 4 e) CaCl 2 f) CH 3CH 2COOH g) CO 2 h) C 10H 22 ph Scale How do we tell if one chemical is more acidic than the other? We use an acidity scale called the ph Scale. There are a few key points to remember about this scale: 1. ph is from to 2. ph of 7 is 3. ph less than 7 is ( 0 being most ) 4. ph greater than 7 is (14 being most ) 21

24 Acids vs Bases Acids: Bases: Naming Them Properties 22

25 Reactions 1. Acid base neutralization Acid + Base Salt + Water HCl + NaOH NaCl + H2O 2. Oxides 3. Acid and Metals 23

26 Mr. Huang Science 10 Collision Theory and Reaction Rates [Text Reference: 6.2 Factors Affecting Reaction Rates] Chemistry Lesson 12 Goal 19: Describe what the collision theory is and how it relates to chemical reactions Goal 20: Describe the different factors that affect reaction rates Collision Theory We are going to assume that all molecules act as. They are constantly moving and when they, they will bounce off each other and energy. If the molecules or particles hit each other with enough force, they may combine. Consider the following reaction and diagram: H2 + I2 2HI When the molecules react, they hit each other and for a split second, they will stick together to form what we can an. This intermediate molecule may then two (or more) new molecules. With this realization, we come to the first rule for collision theory: Rule 1: Factors Affecting Reaction Rate 1. Temperature When temperature, the time of reaction. This means that it takes time for the reaction to finish. Therefore when temperature increases, the reaction rate. Using collision theory, we explain by saying that at higher temperatures, particles will have more energy. When particles are moving faster, there are more for collisions to occur. Hence reaction rate increases. Note: Temperature increases reaction rate. Memorize this!!! 24

27 2. Concentration. When reactant concentration, the time of reaction. This means that it takes time for the reaction to finish. Therefore, when reactant concentration increases, the reaction rate. Using collision theory, we explain by saying that as concentration of a reactant increases, there will be more between reactants. Therefore, reaction rate will 3. Surface Area When the surface area increases, is available for reactants to react. This means that it takes for the reaction to finish. Therefore, when surface area increases the reaction rate Using collision theory, we explain by saying that when the surface area increases, there will be more. Therefore reaction rate will increase. 4. Catalyst and Inhibitors Catalyst: Note: Catalysts are not part of the reaction. This means that at the end of the reaction, you will get back all the catalyst you added in the beginning. Think of it as a tool. Inhibitors: Example: poisons (they prevent your body reactions from working) or antibiotics (they prevent bacterial reactions from working) 25