Unit 1 - Chemical Processes

Transcription

1 Unit 1 - Chemical Processes Chapter 1 - Chemical Nomenclature Watch: An Introduction to Chemistry Unit 1 - Chemical Processes 1 / 57

2 Part I - Chemicals in Action This section will explore ionic and molecular chemical compounds. We will: recognize the relationships among chemical formulas, composition, and names; write the chemical formulas for ionic and molecular compounds, and name these compounds. Unit 1 - Chemical Processes 2 / 57

3 Part II - Understanding Chemical Reactions Chemical reactions can be classified according to the types of reactants involved. We will: balance chemical equations; recognize the types of chemical equations. Unit 1 - Chemical Processes 3 / 57

4 Part III - Controlling Chemical Reactions This section will discuss the rates of chemical reactions. We will: explain which factors affect rates of chemical reactions and why; identify everyday examples of ways in which rates of reactions are controlled. Unit 1 - Chemical Processes 4 / 57

5 Section Introduction to Chemistry What is Chemistry? Chemistry is the study of the properties of materials and the changes that materials undergo. Unit 1 - Chemical Processes 5 / 57

6 Why study Chemistry? It is the central science, leading to a fundamental understanding of other sciences and technologies. It is an extremely practical science that greatly impacts our daily living: improvement to health care conservation of natural resources protection of the environment provision of our everyday needs for food, clothing, and shelter Using chemistry, we have discovefirebrick helpful pharmaceutical chemicals, increased food production, and developed plastics. Unit 1 - Chemical Processes 6 / 57

7 Classifications of Matter Matter is the physical material of the universe. The tremendous variety of matter in our world is due to the combinations of only about 100 very basic substances called elements. How can we classify matter? Unit 1 - Chemical Processes 7 / 57

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9 Pure Substances A pure substance is matter that has distinct properties and a composition that doesn t vary from sample to sample. Examples: Water Oxygen Table salt All substances are either elements or compounds. Elements are composed of only one kind of atom (ex: O, H, Fe). Compounds are substances composed of two or more elements (water, table salt). Unit 1 - Chemical Processes 9 / 57

10 Properties of Matter Physical property - is a characteristic of a substance. Example: Baking soda is a pure substance that is white, solid at room temperature, and dissolves readily in water (ex. changes of state). Physical Change - a change in the size or form a substance which does not change the chemical properties. Freezing - liquid to solid Melting - solid to liquid Boiling - liquid to gas Condensation - gas to liquid Sublimation - solid to gas Unit 1 - Chemical Processes 10 / 57

11 Chemical property - a characteristic behaviour that occurs when a substance changes to a new substance. New substance is formed Gas is produced Colour change Difficult to reverse Heat or light is given off Solid is formed Unit 1 - Chemical Processes 11 / 57

12 Section Chemical Safety Symbols Hazardous Household Product Symbols (HHPS) Toxic - substances that even in small quantities may poison, cause injury or death when swallowed, absorbed through the skin, or inhaled into the lungs. Flammable - substances, usually liquids, that can readily ignite (burn in air) in a wide range of temperature conditions. Unit 1 - Chemical Processes 12 / 57

13 Corrosive - substances or vapours that can deteriorate or eat away the surface of another material. Reactive/Explosive - substances that can react with air, water, or another substance to produce toxic vapours or explode. Watch: Sodium in Water Unit 1 - Chemical Processes 13 / 57

14 Degree of Danger - combined with these three symbols, the previous classification images show the type and extent to which a substance can be harmful. Unit 1 - Chemical Processes 14 / 57

15 Workplace Hazardous Materials Information System (WHMIS) Class A: Compressed gas Class B: Flammable and combustible material Class C: Oxidizing Materials Unit 1 - Chemical Processes 15 / 57

16 Class D: Poisonous and infectious materials Division 1: Materials Causing immediate and Serious Toxic Effects Division 2: Materials Causing Other Toxic Effects Division 3: Biohazardous Infectious Material Unit 1 - Chemical Processes 16 / 57

17 Class E: Corrosive material Class F: Dangerously reactive material NFPA - National Fire Protection Agency Unit 1 - Chemical Processes 17 / 57

18 Exit Slip URL:

19 Recall: Matter is the physical material of the universe. All matter is composed of elements. All elements are composed of very small particles called atoms. What are atoms made up of? Unit 1 - Chemical Processes 18 / 57

20 Atomic structure: Atoms contain two main regions called the nucleus and the electron cloud. The nucleus is composed of two subatomic particles called protons and neutrons. The electron cloud is composed of one subatomic particle called the electron. (a) The Bohr Model (b) The Electron Cloud Model Unit 1 - Chemical Processes 19 / 57

21 The charges of the three key subatomic particles: Protons - Positively charged. Denoted: p + Neutrons - Neutrally charged. Denoted: n 0 Electrons - Negatively charged. Denoted: e Elements on the Periodic Table are in electronically neutral form; i.e. they carry no charge. To be electronically neutral, an atom must have an equal number of protons and electrons. Example: Which atom below is electronically neutral? Unit 1 - Chemical Processes 20 / 57

22 Question: Label the following diagram: Unit 1 - Chemical Processes 21 / 57

23 Section The Periodic Table Periodic Table - A structured arrangement of elements that allows us to explain and predict physical and chemical properties. Unit 1 - Chemical Processes 22 / 57

24 Chemical Families or Groups - Elements in the same vertical column of the periodic table. They tend to have similar physical and chemical properties. Unit 1 - Chemical Processes 23 / 57

25 Symbols on the Periodic Table Unit 1 - Chemical Processes 24 / 57

26 Determining the number of protons, neutrons, and electrons in an atom: For any element: Number of protons = Atomic Number Number of electrons = Number of Protons = Atomic Number Number of Neutrons = Mass Number - Atomic Number Examples - Calculate the number of protons, neutrons, and electrons in the following atoms: 1 Lithium 2 Krypton 3 Sodium 4 Potassium Unit 1 - Chemical Processes 25 / 57

27 Section Bohr Diagrams: A Model for an Atom Each shell or orbit can hold only a certain number of electrons. 1 First orbit - 2 electrons 2 Second orbit - 8 electrons 3 Third orbit - 8 electrons 4 Fourth orbit - 2 electrons The valence shell of an atom is the outermost orbit. The electrons in this orbit are called valence electrons. Unit 1 - Chemical Processes 26 / 57

28 Examples: Draw Bohr diagrams for the following: 1 a helium atom 2 a carbon atom Identify how many valence electrons are present in each. Include the number of protons and neutrons in the nucleus. Unit 1 - Chemical Processes 27 / 57

29 Practice: Draw Bohr diagrams for the following: 1 a potassium atom 2 a nitrogen atom Identify how many valence electrons are present in each. Include the number of protons and neutrons in the nucleus. Unit 1 - Chemical Processes 28 / 57

30 The Nobel Gases The nobel gases behave differently than other elements on the periodic table. Draw Bohr diagrams for the following: 1 Helium 2 Neon 3 Argon What do you notice about the number of electrons in each orbit? The nobel gases do not easily form compounds because their arrangements of electrons are very stable. Their orbits are full. Unit 1 - Chemical Processes 29 / 57

31 When elements have the opportunity, they will give, receive, or share electrons so that their electron arrangements match the most stable electron arrangement of the closest nobel gas. Example: How could lithium obtain an electron arrangement of its closest noble gas? Unit 1 - Chemical Processes 30 / 57

32 Ions Consider lithium (3 electrons). If lithium loses the electron in its outer orbit, than it s left with 2 electrons - the same stable electron arrangement as helium. However, it still has 3 protons. = It has formed an ion. When atoms gain or lose electrons they become ions. Its ionic charge is now 3 + ( 2) = 1. This is written as Li 1+ or Li +. Unit 1 - Chemical Processes 31 / 57

33 If an element loses electrons it becomes positively charged and is called a cation. Example: Li + If an element gains electrons it becomes negatively charged and is called an anion. Example: F Unit 1 - Chemical Processes 32 / 57

34 Examples: 1 How many electrons does Na + have? What type of ion is Na +? 2 How many electrons does Cl have? What type of ion is Cl? Unit 1 - Chemical Processes 33 / 57

35 Practice: What ionic charge would the following elements have to be closest to a noble gas. How many elements would these ions have? What type of ions would they be? 1 Li, Na 2 Be, Mg 3 B, Al 4 C, Si 5 N, P 6 O, S 7 F, Cl Unit 1 - Chemical Processes 34 / 57

36 How Elements Form Compounds Much of chemical activity involves the transfer of electrons from one substance to another. Ionic compounds are generally combinations of metals and nonmetals (cations and anions). These compounds are held together by attractions between opposite charged ions (like a magnetic attraction). This is called an ionic bond. Molecular compounds are generally composed of nonmetals only. Electrons are shared between atoms. This is called a covalent bond. Examples: 1 MgCl 2 (magnesium chloride) 2 H 2 O (water) Unit 1 - Chemical Processes 35 / 57

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38 Examples: Using Bohr diagrams, show the complete electron transfer that results in the formation of the following ionic compounds. 1 NaCl 2 LiF 3 CaF 2 Practice: 1 KCl 2 MgCl 2 3 BeO Unit 1 - Chemical Processes 37 / 57

39 Section Naming Ionic Compounds Steps for naming binary ionic compounds: 1 Name the metal (cation) first. 2 Name the nonmetal (anion) second. For the nonmetal, drop the ending and add ide. 3 Use Roman Numerals in parentheses to indicate which charge of the metal is used. This is only used for metals that make more than one charge. Unit 1 - Chemical Processes 38 / 57

40 Examples: 1 Ca 3 N 2 2 Mg 3 P 2 3 Al 2 O 3 4 CuCl 2 5 FeBr 3 6 CoN Unit 1 - Chemical Processes 39 / 57

41 Practice: Name the following compounds. 1 CaCl 2 2 MgBr 2 3 FeI 3 4 CuCl 2 5 Cr 3 N 2 6 BeO Unit 1 - Chemical Processes 40 / 57

42 Polyatomic Ions Polyatomic ions - groups of atoms that tend to stay together and carry an overall ionic charge. Examples: nitrate - NO 3 hydroxide - OH bicarbonate - HCO 3 chlorate - ClO 3 sulfate - SO4 2 phosphate - PO4 3 Note: They are all anions! Unit 1 - Chemical Processes 41 / 57

43 Steps for naming ionic compounds with polyatomic ions: 1 For polyatomic compounds, name the metal first followed by the name of the polyatomic ion. The endings do not change. Examples: 1 Al(OH) 3 2 NaHCO 3 3 Sn(NO 3 ) 4 Unit 1 - Chemical Processes 42 / 57

44 Practice: Name the following compounds. 1 KNO 3 2 Mg 3 (PO 4 ) 2 3 NaOH 4 Pb(NO 2 ) 4 Unit 1 - Chemical Processes 43 / 57

45 Section Writing Formulas for Ionic Compounds Steps: 1 Write the ionic charges above the symbols. 2 Determine the lowest number of each element that would make the entire compound electronically neutral. i.e. Crisscross the numbers, using them as subscripts. Remember to reduce when appropriate. Key fact: The sum of the charges on the positive ions equals the sum of the charges on the negative ions. Examples: 1 calcium iodide 2 sodium phosphide 3 calcium chloride Unit 1 - Chemical Processes 44 / 57

46 Practice: Write the formulas for the following compounds. 1 sodium bromide 2 strontium nitride 3 potassium phosphide 4 magnesium nitride 5 zinc iodide Unit 1 - Chemical Processes 45 / 57

47 Note: Some metals can make more than one kind of ion. Roman numerals in brackets indicate the charge of the ion (not how many are in the formula). Examples: 1 iron (III) oxide 2 iron (II) oxide Unit 1 - Chemical Processes 46 / 57

48 Practice: Write the formulas for the following compounds. 1 cobalt (II) chloride 2 nickel (III) oxide 3 lead (IV) selenide 4 tin (II) nitride 5 iron (III) phosphide Unit 1 - Chemical Processes 47 / 57

49 Note: Ionic compounds may include polyatomic ions. Reference the List of Polyatomic Ions to determine the charges of the polyatomic ions. Remember to put the entire polyatomic ion in brackets if you need more than one! Examples: 1 sodium carbonite 2 aluminum sulfate Unit 1 - Chemical Processes 48 / 57

50 Practice: Write the formulas for the following compounds. 1 sodium chlorate 2 magnesium phosphate 3 silver nitrate 4 barium sulfite 5 iron (II) nitrite Unit 1 - Chemical Processes 49 / 57

51 Section Molecular Compounds Molecular compound - formed when nonmetals (anions) share electrons with other nonmetals (anions). Covalent bond - a shared pair of electrons held between two nonmetal atoms that holds the atoms together. Unit 1 - Chemical Processes 50 / 57

52 Examples: Using Bohr diagrams, show the complete electron sharing that occurs in the following molecular compounds. 1 H 2 2 Cl 2 3 H 2 O Unit 1 - Chemical Processes 51 / 57

53 Practice: Using Bohr diagrams, show the complete electron sharing that occurs in the following molecular compounds. 1 F 2 2 HF 3 CH 4 Unit 1 - Chemical Processes 52 / 57

54 Diatomic Molecules These are molecules composed of two of only one type of element. The most common are: Acronym: HOFBrINCl H 2 O 2 F 2 Br 2 I 2 N 2 Cl 2 Why would these atoms bond with themselves to form covalent bonds? Unit 1 - Chemical Processes 53 / 57

55 Writing Formulas for Molecular Compounds Steps: 1 Write the symbols of each nonmetal. 2 Write the appropriate subscripts for each nonmetal that corresponds to the prefixes used. Note: The prefix mono is never used on the first nonmetal. mono di tri tetra penta hexa hepta octa nona deca Unit 1 - Chemical Processes 54 / 57

56 Examples: Write the formulas for the following molecular compounds. 1 carbon dioxide 2 dinitrogen trioxide 3 carbon tetrafluoride Practice: Write the formulas for the following molecular compounds. 1 dihydrogen monoxide 2 diboron trioxide 3 phosphorus trihydride Unit 1 - Chemical Processes 55 / 57

57 Writing Names for Molecular Compounds Steps: 1 Write the name of the first nonmental and then the second. 2 Place the appropriate prefixes in front of each of the names. The prefixes correspond to the subscripts of each element. 3 Drop the ending of the last element named and add -ide. Note: Sometimes prefixes are shortened when the ending vowel of the prefix conflicts with a starting vowel in the compound. This makes the name easier to pronounce. Unit 1 - Chemical Processes 56 / 57

58 Examples: Name the following molecular compounds. 1 CS 2 2 N 2 O 4 3 P 4 S 10 Practice: Name the following molecular compounds. 1 CO 2 CF 4 3 C 2 H 6 Unit 1 - Chemical Processes 57 / 57