Science 10 - Unit 2 Chemistry Past Paper Answer Key PDF

Science 9 Unit 2: Chemistry Book 2: Atoms, The Periodic Table & Bohr Models Name: Block: 1  1 Periodic Table of the Elements...

Science 9 Unit 2: Chemistry Book 2: Atoms, The Periodic Table & Bohr Models Name: Block: 1  1 Periodic Table of the Elements 18 1 2 H He Hydrogen Helium 1.01 2 13 14 15 16 17 4.00 3 4 s 6 7 8 9 10 Li Be B C N 0 F Ne Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon 6.94 9.01 10.81 12.01 14.01 16.00 19.00 20.18 11 12 13 14 15 16 17 18 Na Mg Al Si p s Cl Ar Sodium Magnesium Aluminum Silicon Phosphorus Sulfur Chlorine Argon 22.99 24.31 3 4 s 6 7 8 9 10 11 12 26.98 28.09 30.97 32.07 35.45 39.95 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton 39.10 40.08 44.96 47.87 50.94 51.99 54.94 55.85 58.93 58.69 63.55 65.38 69.72 72.63 74.92 78.97 79.90 84.80 37 38 39 40 41 42 43 44 45 46 47 48 49 so 51 52 53 54 Rb Sr y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon 85.47 87.62 88.91 91.22 92.91 95.95 98.91 101.07 102.91 106.42 107.87 112.41 114.82 118.71 121.76 127.6 126.90 131.29 55 56 57-71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba Lanthanides Hf Ta w Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Cesium Barium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury Thallium Lead Bismuth Polonium Astatine Radon 132.91 137.33 178.49 180.95 183.84 186.21 190.23 192.22 195.09 196.97 200.59 204.38 207.2 208.98 [208.98] 209.99 222.02 87 88 89-103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 Fr Ra Actinides Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og Francium Radium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Parmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson 223.02 226.03 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium 138.91 140.12 140.91 144.24 144.91 150.36 151.96 157.25 158.93 162.50 164.93 167.26 168.93 173.06 174.97 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 u 2 Ac Th Pa Np Pu Am Cm Bk Cf Es Fm Md No Lr Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium 227.03 232.04 231.04 238.03 237.05 244.06 243.06 247.07 247.07 251.08 257.10 258.1 259.10  DARTS o F AN PART A: THE ATOM & subatomic particles _ All is made of tiny [,, particles called ___ Atoms are made of even smaller _____ particles called and ------ particles in the _____ that have a mass of --- The number of protons determines the _____ of an atom. For example hydrogen has __ , helium has ______ charged NEUTRON particles in the _____ shells or ---- _____ particles in of an electron is --- 0 0 ----- of the atom. that of a proton, so it does not They have no _____ add ----- have a mass of _ ____ is-t-he_ o_n -ly-element 0 0 0 that does ___ have at least one neutron in its Atoms are so small! The dot on this i contains about Atoms are mostly ___ space. I trillion atoms! The mass comes from the---- 3 and ____ in the nucleus! What are atoms and how do we know they exist? An atom is the particle of an that still has the identity and properties of the element. Atoms are made up of particles (particles that are smaller than atoms). These particles are , and Summary of the Parts of an Atom: Name Symbol Charge Location Relative Mass The Nucleus At the of every atom is a of the space inside an atom is taken up by the , the nucleus is As atoms get bigger, the in the nucleus repel (push away from) each other more. So are required to make the nucleus stable. o Neutrons are though to be needed to hold all the protons together in the nucleus o The bigger the nucleus, the are needed. True of False: a) All matter is made of small particles called atoms b) Atoms of one elements are different form the atoms of other elements c) Electrons are locate din the nucleus of an atom d) Most of the mass of an atom is concentrated in it’s electrons e) The nucleus contains protons and electrons f) The nucleus is the tiny, dense, central core of the atom. 4  Atomic Number (Z) The number of ___________________ in an atom is known as the atomic number or proton number. It is the smaller of the two numbers shown in most periodic tables. (usually on top...dependswhere you're looking) atomic number = always the ______________for a particular element. The number of protons _______________________the element! is also equal to the _________charge of the nucleus o this is also called the positive __________________________. in ther periodic table atoms are listed from ___________ to right by _________________ atomic number If an atom has a Z = 12, then it MUST be an atom of: If an atom has a nuclear charge of +24, then it MUST be an atom of: What is the atomic number of polonium? What is the positive nuclear charge of lead? The overall charge on an atom is zero because the number of ____ = number of ____ How many electrons? Atoms have no overall electrical charge and are___________ This means atoms must have an ___________number of positive protons and negative electrons. The number of electrons is therefore the same as the atomic ___________. 5  Mass Number (A) Atoms of a certain element always have the same number of _______________, but can have different numbers of neutrons….these are called ____________________. They are the different "versions "of an atom of an element that can exist. Mass number = the total number of particles with mass (_______________ + _________________) in the __________________ of an element o ___________________ have a mass of almost zero, which means that the mass of each atom results almost entirely form the number of protons and neutrons, ___________electrons. Mass number is ALWAYS reported as a __________________________________ The mass number _______________ appear exactly like this on the periodic table. o BE CAREFUL! The larger of the two numbers (usually on the bottom) shown on your periodic table is the relative _________________. It is the average mass number of the element (average of the isotopes). o We must ROUND the atomic mass to the nearest WHOLE NUMBER in order to determine the number of neutrons. o RULE: numbers 04 = ROUND ______ 59 ROUND _____ _________________ are different atoms of a particular element that have the SAME number of ________________ but a DIFFERENT number of _________________. The mas number _________________ be used to identify the element. o Example: Both He and H can have a mass number of __________ H : ____ p,___ n , He: ____ p,____ n What's the mass number? How many neutrons? 6  Example: Calculating the number of neutrons in an atom of lithium Overall charge of an atom: 1. Label the parts of the atom to the right. Include the following labels: proton, electron, neutron, nucleus. 2. What elements is represented by this diagram? How do you know? 3. What is the charge of this nucleus? What is the charge of this atom overall? 4. What is the mass of this atom? 5. Using a periodic table, look up titanium. a. What is its atomic number? b. How many protons does a titanium atom have? c. How many electrons does it have? 6. What element has 78 protons? 7. What is the atomic mass of a sample of chlorine that has 19 neutrons? 8. What atom has 18 electrons? 7 PART B: Elements 8  ASSIGNMENT #1: Getting to Know Subatomic Particles pg 9 + Atomic Structure Worksheet pages 10-11 This assignment is to be completed below in the space provided. Getting to Know Subatomic Particles: Use your periodic table to complete the table below: # of Rounded Atomic # of # of Atomic neutrons Element Symbol Atomic Period Number protons electrons Mass (show Mass work) Oxygen O 8 8 8 15.999 16 16 - 8 = ​8 2 Helium Carbon Aluminum Calcium Sodium Potassium Nitrogen Silicon Iron Hydrogen Uranium 9 10 11 The Periodic Table...OF ELEMENTS! The periodic table is made up of ________________ o An element is a ______________________ that ________________________ into anything simpler (if contains only ________ kind of atom) Every element has its own unique ___________ and _____________ Examine the list of elements to the left. Note the different ways in which they were named. Add three examples to each of the following: A. The symbol of some elements is just the first letter (always capitalized). B. When the first letter had already been used, the first and second letter was used (second letter always lowercase). C. When the first and second letters had been used, the first and the third were used (third letter always lowercase).. D. Some elements were named before English became the language of science, so their symbols derive from their Latin names. Can you find an element name that is related to a How about an element name related to a country/continent? famous scientist? 12 On Earth about _________ elements occur naturally (ex. ___________________________). There are many elements that do not occur naturally but are synthesized (___________) in __________________________. As you’ve seen each element has a unique _______________ and ________________. The symbol is usually _______ or _______ letters. The first letter is always ___________________ and the remaining letters if there are any are ________________________________________. The names and symbols of the elements are accepted and used by scientists all ________________________________. Many element names come from Latin words, others are named for countries or to honour scientists of note. About ___________ of the elements found in the periodic table are metals. Metals Non-Metals 13  Write the symbol for the following elements. Oxygen Hydrogen Chlorine Potassium Phosphorus Iodine Magnesium Nitrogen Fluorine Manganese Iron Carbon Copper Calcium Zinc Cobalt Sodium Molybdenum Sulphur Mercury Write the name of the following elements. As Rn Pb Al Cu K Ba Ag He Pu Ne Sr Si Am U Au Sn Ra Pt Ge Thinking ahead about Compounds & Chemical Formulae As you know a compound is a p____________ s___________________ that is made up of _____ or more different types of atoms. These different types of atoms come from different types of e_____________________. Elements combine to form ___________________, something that we will look at later in this course. 14  ASSIGNMENT #2: Chemical Formula Practice page 15 This assignment is to be completed below in the space provided. 1. For each of the following molecules, identify the kind of atoms and the number of each. The first one is done for you. Chemical Formula Kinds and Number of Atoms in Each Molecule CaCO3 1 atom calcium, 1 atom carbon, 3 atoms oxygen AgBr PbS2 MgCl2 Al2O3 PbCl4 Fe2O3 AlP NH4OH NaHSO4 PbSO3 2. Each particle of the following contains the atoms listed. Write the formula of each compound. The first one is done for you. 1. One copper atom and one sulphur atom CuS 2. One nitrogen and three hydrogen atoms _________ 3. Two hydrogen and one sulphur atom _________ 4. One hydrogen, one nitrogen and three oxygen atoms _________ 5. Two potassium, one carbon and three oxygen atoms _________ 6. Two aluminium and three oxygen atoms _________ 7. One iron, one phosphorus and four oxygen atoms _________ 8. One nitrogen, four hydrogen, one carbon and three oxygen atoms _________ 9. One potassium, one chlorine and three oxygen atoms _________ 10. Six carbons, twelve hydrogen and 6 oxygen atoms _________ 11. One carbon, three hydrogen, one oxygen and one hydrogen _________ 15  ACTIVITY: Elements and the Periodic Table Activity 1: Comparing Properties of Elements An element is a substance that cannot be broken down into simpler substances by heating it or causing it to react with other chemicals. The smallest unit of an element is a tiny particle called an atom. Each different element has a unique atom. Everything around you is made from incredibly small atoms of one or more of these elements. A pure sample of an element contains many atoms of the same type. For example, the millions of iron atoms that make up a piece of iron metal are of the same type and have the characteristics of iron. Iron atoms, however, are very different from atoms of other elements, such as gold or oxygen. All elements have unique properties. It is atoms of an element that determine its properties. Most elements are rarely found in pure form. Atoms of different elements tend to combine chemically, or react, with each other. Scientists say these elements are reactive. When elements react, they can form substances called compounds. One familiar compound is water, a combination of two hydrogen atoms and one oxygen atom. Challenge: How can elements be grouped based on their physical and chemical properties and how are they related to compounds? Materials: Element Cards, Element Family Cards Part A: Classifying Elements 1. With your partners, spread the Element Cards out on a table. Each card provides information about an element. Two categories might be unfamiliar, reactivity (how likely the element is to react chemically with other elements) and number of bonds to hydrogen (the number of hydrogen atoms that usually combine chemically with this element). 2. Examine the information on each card carefully, noting similarities and differences among elements. 3. Working together, sort the elements into at least three groups. Each group of elements should have at least two similar properties. 16 4. List the groups you have made and the common features of each group. Be sure to record all of the elements in each group. Group Elements in Group Common Features of the Group 1 2 3 4 (if needed) Part B: Comparing Classification Systems 5. Your group will receive four Element Family Cards. Each card describes a group of elements called a family. Based on the information on the Family Cards, place each element under a Family Card. 6. Arrange the elements in each family in order from lowest atomic mass at the top to highest atomic mass at the bottom. Place the column on a half sheet of coloured paper. 7. Line up the four columns of elements to form a table, so that the elements are in columns and rows. Use the atomic masses of the elements to decide on an order for the columns. 17 8. Record your new classification system, complete with: - Family names - Similar properties within each family - Elements in each family in order of increasing atomic mass Family Name Similar Properties Elements Element Mass Element Mass Element Mass Element Mass + atomic mass Analysis: 1. Which of the properties listed on the Element Cards are: a. Physical properties? b. Chemical properties? 2. How did your first classification system compare to the second classification with the Element Family Cards? 18 3. In what ways could grouping elements help scientists understand their properties? 4. Use the table of elements you constructed in step 8 above to find the family or families of elements that are: a. Not usually reactive: b. Highly reactive: c. All metals: d. All solids: e. All gases: 5. The element strontium (Sr) has properties that make it belong in the Alkaline Earth Metals family, directly below calcium (Ca) on your table of elements. Design an Element Card for strontium that shows its symbol, name and the properties you predict it will have: 19 PART C: The Periodic Table History of Atomic Theory The ancient Greeks believed that there were four types of matter: ______________________________________. Democritus (400BC) proposed the idea of _________ and that they are __________________. Science though, _________________ this idea and it took hundreds of years to pass before Democritus’ idea was accepted. Skipping ahead to the ___________, scientists had identified _______________, but there was no way of _________________ them. o Some tried to classify them based on ____________________ or by how they _____________ with other elements. o None of these worked for ___________________ The Periodic Table of Elements In 1867, Dmitri Mendeleev wrote down the characteristics of all the known elements on cards and arranged them into a pattern that made sense. o When elements were listed by ____________________ he noticed that certain ____________________ seemed to repeat with a regular pattern. o He put them in ____________________, and when properties repeated he started a ___________________ The Early Periodic Table Horizontal rows (______________) has masses increasing left to right Vertical columns (_____________) have common properties Gaps were left when properties did not match properties _________________ Elements were predicted to fill ___________ 20  The Current Periodic Table Mendeleev’s table had ______________________________ o His ____________________ evolved through the work of others Now, elements are ordered by __________________, not ____________________ The table in use today reached its current form in the ____________ Properties of Elements All elements are different from each other, and have ______________________________ o These _________________ can be used in identifying different elements Elements with similar properties are often ____________________________ One common grouping is _____________________________________________ Metals, Non-Metals and Metalloids Metals are found on the left of the periodic table (except _________________), non-metals on the right, and _________________ in between. The _______________ divides them.  metals  metalloids  non-metals Metals: : Metalloids: Non-Metals: ___________, shiny, can be shiny or dull, often Dull, not ductile, __________, ductile, malleable, magnetic, conduct electricity poorly, non-magnetic, and ______ and good conductors of both but do not conduct conductors of heat and electricity __________________ ___________________ Some are solids, some are liquids Most are _____________ most are solids at and some are gases at at room temperature _________ temperature ____________ temperature (exception: _________) 21 ASSIGNMENT #3: Getting to know The Periodic Table This assignment is to be completed below in the space provided. You will need to research the names and locations of these periodic table groups/families You will also learn where the metals, non-metals and metalloids are on your periodic table. Be sure to use ARROWS to show the direction of Groups & Periods! You DO NOT have to write in elements symbols or atomic numbers. 22  Fill in the following table. Property Metals Non-Metals Metalloids Colour/Lustre Ductile Malleable Magnetic Conductor Other Important Groups to Know You should be able to _____________ these groups on the periodic table, and know their properties. Group 1 (without H) – Alkali Metals Highly reactive _____________(reactivity increases with ___________, so as you move ____________ the group they become more reactive) Burn spontaneously in oxygen and in __________________ ____________ solids at room temperature _____________ is part of many batteries, ________________ is part of fertilizers 23 Group 2 – Alkaline Earth Metals __________________ metals that will burn in oxygen and water if _______________ Solids at ____________ temperature Group 17 – Halogens All are highly _______________ non-metals Fluorine and chlorine are _____________, bromine is a liquid, and iodine is a _______________ at room temperature Widely used in _______________________ (water, household, medical) and bleaching (clothes, paper) Family 18 – Noble Gases Are the most stable and _________________ elements in the table All are colourless ___________ at room temperature They are used inside lights to produce different ___________ (e.g. neon signs) 24  Families of elements D A E F B C Use the simplified periodic table shown above to answer questions 1 to 12. To which region does each element or family belong? Place the letter corresponding to the shaded region on the blank line. You can use regions more than once. You can use the periodic table on page 201 to help you answer these questions. 1. helium 2. lithium 3. fluorine 4. beryllium 5. halogens 6. noble gases 7. alkali metals 8. alkaline earth metals 9. non-metallic elements that are strongly reactive 10. metallic elements that are strongly reactive 11. metallic elements that are reactive 12. non-metallic elements that are very unreactive 25  ASSIGNMENT #4: Periodic Table Review pg 26-29 This assignment is to be completed below in the space provided. 1. The left-hand column in the chart below contains statements about various elements. Write the name and symbol for the element each statement refers to. 2. For each group, decide which element does not belong with the rest. Explain why. a. Si Ge Sn P ________________________________________ b. Ti S Pt Fr ________________________________________ c. N C Sn Xe ________________________________________ d. Sr F Cd I ________________________________________ 3. Which one of the elements does not have the properties held by the rest of the group? a. Cs Ba K Na ________________________________________ b. Ca Cd Hg Zn ________________________________________ 26 Review Questions. 1. What is a family? _______________________________________ 2. What is a period? _______________________________________ 3. What is the symbol for the following elements? a. Magnesium ______ b. Potassium ______ c. Iron ______ d. Copper ______ 4. What are the names of the following elements? a. C _________________________ b. Cl _________________________ c. Au _________________________ d. Sr _________________________ 5. In what period are the following elements found? a. He ______ b. Ge ______ c. Rb ______ d. I ______ 6. In what group (family name) are the following elements found? a. Sulfur ___________________________ b. Ca ___________________________ c. Iodine ___________________________ d. Fe ___________________________ 7. List two atoms from each of the following groups: a. Halogen ______________ b. Noble Gas ______________ c. Alkali metal ______________ d. Alkaline Earth Metal ______________ 8. What is the symbol for silver? __________ 9. Ni is the symbol for what element? __________ 10. State the period number(s) that contain only eight elements: ________________ 27 Using the periodic table Vocabulary average atomic mass metalloids atomic number multiple ion charge electrons noble gases families non-metals good periodic table halogens periods ions poor ion charge properties metals Use the terms in the vocabulary box to fill in the blanks. You can use each term more than once. You will not need to use every term. 1. The organizes the elements according to their physical and chemical. 2. The periodic table is divided into seven horizontal rows called and 18 vertical columns called. 3. appear on the left side of the periodic table. These elements are conductors of heat and electricity. 4. appear on the right side of the periodic table. These elements are conductors of heat and electricity. 5. The form a zigzag staircase arrangement on the periodic table. These elements have properties similar to both and. 6. The refers to the number of protons that an atom has in the nucleus. 7. The is the weighted average of the masses of the atoms of an element. 8. A(n) is an electric charge that forms on an atom when it gains or loses electrons. 9. Some metals, like platinum and cobalt, form in more than one way. In other words, they have a(n). 28 The periodic table and Use the following diagram to answer questions 7 and 8. chemical properties Match each Term on the left with the best Descriptor on the right. Each Descriptor may be used only once. Term Descriptor 7. What does the “30” refer to? A. ion charge 1. halogens A. most reactive metals B. most reactive non-metals B. average atomic mass 2. noble gases C. have properties of both C. atomic number 3. alkali metals metals and non-metals D. most unreactive elements D. family number 4. alkaline earth metals E. includes beryllium and 8. What does the “2+” refer to? magnesium A. ion charge Circle the letter of the best answer. B. average atomic mass 5. What is the name of a horizontal row in the C. atomic number periodic table? D. family number A. column 9. To which of the following groups does B. family oxygen belong? C. period A. gas D. group B. metal 6. Which of the following are metalloids? C. metalloid I. silicon D. non-metal II. boron 10. Which of the following is the same as the atomic number of an element? III. neon A. number of protons A. I and II only B. number of neutrons B. I and III only C. number of electrons C. II and III only D. number of ion charges D. I, II, and III 29  Part D: The Bohr Model Using Standard Atomic Notation On the upper left of the element symbol is the atomic __________(rounded to the nearest whole number) On the lower left of the element symbol is the atomic _____________________ (number of protons). Ex. Consider the element gold. Its symbol is Au. Its mass number is 197 and its atomic number is 79. 197 79 Au Written in standard atomic notation it becomes: Write the standard atomic notation for germanium, uranium, and colbalt. Modeling Atoms with Bohr Diagrams Atoms are so __________ that in order to study them, we need to create _______________ The current atomic model is known as the ______________________ o Electrons are always moving in 3D space around the ____________ The model that we will learn today represent the atom at __________________________ o It’s a way of representing the __________________________ of electrons in the “cloud” It’s important to remember that an atomic model is a _____________________ version of an atom, and it’s completely ___________ in terms of ____________ Bohr Diagrams A Bohr diagram is a diagram that shows how many _____________ are in each shell surrounding the nucleus. Named in honour of __________________, a Danish physicist who developed several models for showing the arrangement of electrons in atoms. There are three main background questions to explore before we start drawing Bohr diagrams. 30 1. _________ of a Bohr Diagram 2. How does an Electron’s _____________ Correspond to its _____________? Imagine climbing a ________. As you go up each rung, you gain more and more ___________________________ o This is similar to the way in which electrons have _________ energy as they orbit _____________ from the nucleus The shells of an atom are named _____, _____, _____, and _____ going from ___________ to furthest from the _____________ 3. How do ________________ Fill the _________________? 31  Drawing a Bohr Diagram 1. Write the element’s __________ with the ________________ at the TOP left and the ________________ at the BOTTOM left 2. ______________ the number of __________ in the atom. Write the number of protons (p+) and neutrons (n0) as the _____________ 3. ____________: How many electrons does the ____________ atom have? 4. _________ the K shell. Fill the K shell with the first ______ electrons. Make your electrons nice and _______! 5. Continue drawing each shell and _____________ with electrons until you have accounted for all the atom’s electrons. In the diagram below, identify the elements by the Bohr model diagrams are shown. Write the symbols of the elements in the spaces provided. 32 Part E: Valence Electrons The electrons in the _______________________ shell. These are the electrons that participate in chemical _____________________. Valence electrons can be shared or ___________________ by another atom. Noble gases do not react unless under _________________ conditions. This is because their valence shell is _________________. An atom that has lost valence electrons is a ________________ ion. An atom that has gained valence electrons is a _______________ ion. For the following Bohr diagrams, answer the following questions: Number of protons _____ Number of electron shells _____ Number of electrons _____ Number of valence electrons _____ Ion or Atom _________ Number of protons _____ Number of electron shells _____ Number of electrons _____ Number of valence electrons _____ Ion or Atom _________ Number of protons _____ Number of electron shells _____ Number of electrons _____ Number of valence electrons _____ Ion or Atom _________ The following Bohr model diagram represents an oxygen atom. Examine the diagram, then answer the following questions: a) Why is this not a stable electron arrangement? b) What would make this atom stable? c) Use a different colored pen to adjust the diagram so that it shows a stable electron arrangement. 33  Bohr Model Scavenger Hunt Answer Sheet For each problem, write the name of the Bohr model in the boxes below. You may need to reference a periodic table to help you. *start here! *end here! 34  ASSIGNMENT #5:Bohr Model Practice, Worksheet pages 36-37 This assignment is to be completed below in the space provided. Use the innermost circle as the nucleus, and fill the electron shells with the correct number of electrons for each of the first 20 elements in the Periodic Table. eg. Hydrogen has been completed for you as an example. 1. What is the pattern between the number of valence electrons and the group number of the periodic table? 2. What is the pattern between the number of electron shells and the period number of the periodic table? 35  1 18 2 1 2 13 14 15 16 17 3 5 6 7 8 9 10 2 @ @) @) @) @ 3 (@) Drawing Bohr model diagrams 1. Refer to the Bohr model chart ABOVE to help you complete the following table. Some answers are provided for you. (Hint: Remember that the maximum number of electro1s in the first three shells is 2, 8, and 8.) Atom/ion Atomic number Number of Number of Number of protons electrons electron shells neon atom 10 10 10 2 fluorine atom I sodium atom argon a:om chlorine atom potassium atom 2. Use the table above to draw the Bohr model diagram for the following atoms and ions. Argon atom Chlorine atom Potassium atom 36 Use your periodic table to answer the following. a. number of protons __________________ b. number of electron shells _____________ 7p 7n c. number of electrons _________________ d. number of electrons in outer shell _____________ e. element _______________________________ a. number of protons __________________ b. number of electron shells _____________ 6p 6n c. number of electrons _________________ d. number of electrons in outer shell _____________ e. element _______________________________ a. number of protons __________________ b. number of electron shells _____________ 8p 8n c. number of electrons _________________ d. number of electrons in outer shell _____________ e. element _______________________________ a. number of protons __________________ b. number of electron shells _____________ 10p 10n c. number of electrons _________________ d. number of electrons in outer shell _____________ e. element _______________________________ These four elements are all in the same horizontal row (period) of the periodic table. What is the same about electron shells for elements in the same period? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ What is different about the electrons in the outer shell for elements in the same period? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 37 Part F: Periodic Table Trends In chemistry the term ______________________ refers to a regular pattern in the properties of elements based on their atomic structure. This is the pattern that Mendeleev predicted. When the pattern repeated, he began a new_______. The periodic table is a powerful tool for analyzing trends in ____________ and _____________. Atomic Size Trends: Observe the sizes of the atoms in each group and period shown in the diagram below. Do you see a pattern? 1. Atomic size ___________________ moving DOWN a group/column. as you move down a __________, elements have atoms with ________ energy _____________. the ___________ the number of electron shells, the ____________ away from the nucleus the valence electrons are if the electrons are farther away, the atom is __________________. 2. Atomic size ___________________ moving LEFT to RIGHT across a period/row. elements have ________________ numbers of electrons in their ______________ shells as you move LEFT to RIGHT. as the number of electrons increases, so does the number of __________ in the nucleus. the attraction between the n__________ valence electrons and the p_______________ nucleus is very strong. with each electron added, the outer shell is pulled _____________ to the nucleus and the atomic size _____________ 38 Reactivity Trends: Compare what happens when potassium (A) and sodium (B) are added to water: You can see that the reaction is _________ vigorous and violent in 'A', water + potassium. Why is this the case? What is similar about potassium and sodium? ___________________________________ What is different about potassium and sodium? __________________________________ Because ______________ valence electrons are farther away from the nucleus than the electrons in a ________________ atom, the attraction to the nucleus is ______________. Electrons further from the nucleus require ___________ energy (are easier) to remove. The adding and removing of electrons is what is involved in c___________ r____________. This is why we would say that ____________ is more reactive than _______________. This pattern repeats throughout the periodic table with the exception of the noble gases. the noble gases have a FULL valence shell, they are stable and ____________ 1. Explain why atoms get larger down a group on the periodic table: 2. Explain why atoms get smaller from LEFT to RIGHT across a periodic table: 3. Why is an alkali metal MORE reactive than an alkaline-earth metal in the same period? 39  ASSIGNMENT #6 :Bohr Model Review Worksheet pg 40 This assignment is to be completed below in the space provided. Bohr Model Review Worksheet Use the description sheet and the periodic table to help you complete the following Bohr models. 1. How many electrons can each shell hold? a. 1st = _________ b. 2nd = _________ c. 3rd = _________ Atomic Atomic Element Protons Neutrons Electrons Bohr Model # Mass Carbon 6 6 6 Hydrogen 1 1 Lithium 3 3 3 Magnesium 12 24 Boron 5 11 40