The Electron Arrangement of Atoms Impacts Their Chemical Nature

Unit 2 : The electron arrangement of atoms impacts their chemical nature BC Science Connections 9 Teaching Notes Unit 2: The electron arrangement of atoms impacts their chemical nature Unit 2 Assessment Answers to Unit 2 Review Questions 1. a) skin protection safety; wear gloves while working with materials b) clothing protection safety ; wear protective clothing as appropriate such as lab apron c) eye safety ; wear safety goggles d) fire safety ; use care around open flames; be sure you know how to light and use a laboratory burner safely e ) chemical safety; handle substances carefully; read and understand any safety warning labels for these chemicals f ) electrical safety; make sure your hands are dry; report damaged equipment to your teacher immediately ; place electrical cords where people will not trip over them; pull the plug , not the cord 2. Con: that this makes the table very wide and difficult to print on a single page or that it leaves a lot of empty space in the middle of the table. Pros: it is easier to see where these elements fit in the sequence of increasing atomic numbers and this version makes it easier to see which elements are nearby the lanthanides and the actinides in the table. 3. Mattel - nuU ' lfi - HitHiionttypi- of juticW rorikatm ctf teat* typ+ i cffufeckF not Pure Substances Mixtures c*nbt *Ltl*T efen* of QCiCwn Element Copyright 978 1 25 965137 3 -- - - -Hill R 2 «** !Ijp * Compound 264 Unit 2 : The electron arrangement of atoms impacts their chemical nature BC Science Connections 9 Teaching Notes 4. Sample outline : metal wml -metal non-metal o group _ C sikoii mslaii I pwnx) halogens nobia rwtaft 5. a) oxygen 6. Atoms with a full valance shell of electrons are less reactive than elements without filled valance shells. Most reactive elements are those with one valence electron or one fewer valence electron from a full valence shell. 7. a) The element has atomic number 12 b) the full chemical name of the element is magnesium. b) neon c ) lithium c) and d) The element forms this ion because losing two electrons makes it have a filled valence shell. Mg 8. Mp a) If this model represents an atom, which is neutral, it is neon; it has 10 electrons and 10 protons b) If this model represents an ion with a charge of 2+ it would be magnesium . Magnesium has 12 protons and with 10 electrons it would have a 2+ charge c) If this model represents an ion with a charge of 1- it is fluorine. Fluorine has 9 protons so with 10 electrons it would have a 1- charge. , , - Copyright © McGraw Hill Ryerson 2017 978 1 25 965137 3 -- - - 265 Unit 2 : The electron arrangement of atoms impacts their chemical nature BC Science Connections 9 Teaching Notes 9. Properties of Neutral Atoms Symbol Atomic Number Number of Electrons Number of Protons Ne 10 10 10 Li 3 3 3 Ca 20 20 20 Ar 18 18 18 10. Noble gases are relatively inert because they don't form chemical bonds. Atoms form chemical bonds by sharing or exchanging electrons so that they have a filled valence shell. As seen in the Bohr diagram for neon, the noble gases already have filled valence shells so they are stable without bonding. 11. One trend is that atoms get larger as you move down a group in the periodic table so sodium atoms are large than lithium atoms. Another trend is that the alkali metals become more reactive as you move down the group, so sodium is more reactive than lithium. 12. a) LiCl b) ZnS c) CuCl2 d) NH4CH3 COO e) Mn(N03)3 f ) Co3(P04)2 13. a) The name of the compound is calcium sulfate b) CaS04 c) This compound should have a high melting point, be hard and brittle, and conduct electric current when liquid or dissolved. , 14. a) SO2 b) SiBr4 c) PCI5 d) N2O3 15. a) Multivalent means that chromium can form ions with more than one charge , b) Chromium can form 3+ and 2+ ions c ) Chromium and chlorine can form CrCl3, which is chromium(III) chloride, and CrCl2, which is chromium(II ) chloride. , 16. a) sulfur dichloride is a covalent compound b) aluminum bromide is an ionic compound c) nickel(II) sulfate is an ionic compound d) diphosphorus pentoxide is a covalent compound 17. Ionic bonds are formed by a strong attraction between oppositely charged ions. The metal element loses one or more electrons to the non-metal element so that they form positive and negative ions. This transfer of electrons results in full valence shells for each type of ion. Covalent bonds form when two or more non-metal atoms share valence electrons to result in full valence shells for each atom in the - Copyright © McGraw Hill Ryerson 2017 978 1 25 965137 3 -- - - 266 Unit 2 : The electron arrangement of atoms impacts their chemical nature BC Science Connections 9 Teaching Notes molecule. Both types of bonds are the same because they allow the atoms to have filled valence shells. The types of bonding are different because, in the case of ionic bonding the electrons are transferred , and in the case of covalent compounds the electrons are shared. 18. a) baking soda is ionic, cooking oil is covalent, table salt is ionic, lip balm is covalent , candle wax is covalent, sugar is covalent, dishwasher soap powder is ionic. b) Answers could include that baking soda decomposes so it is hard to know if it has a high melting point and sugar is soluble in water so it is different from the other covalent compounds. 19. An example is given below: h Lhftt 4 Hefei de mentor 421 'UtUtal'TdMli r£< km? Orvr ths name oflir fix I tie raeiil wilt b ps&T SEdt i3t iht riurbiw- r ofitcirac (amt racro ud fw t 3v 4 *E«dl 4 f li it* nEttl tn'iLOvale nf* T Islbe compouni binary0 DbhJTrtW tV of th* t 3wu$f OH ( hr into* of the second element wdfli a. pH" x ID incxite tlit ttochatgft wrih FLUIMTI numerals tifej tiv name of EWSfcf r of it'ifij la1 » end ofthf jirtfu: for accries ) bid ui Qrw lie DO HE cf thr meBal fnlbn*d by tie name of the negative - .-po'inri birtiy jr »n Osw tl* SUIT* of Ihe ire tel Foliowed. by fee name of U» ronmelal wilt an Ide' enAi , ^ Gcvx U* same of Ilf tnflilfolkuwdbylbt hswof ii* novtoirt*] vrtttan ds"eBcb . ^ ^ CM the mew of the trel il foliowdbyl3* taint Of d tagifc » &. * * - 20. a) Turning off the hot plate and/or unplugging the hot plate before checking to see if the container of liquid can be left on the hot plate before exiting the classroom and the building. b) First removing the test tube from the heat and allowing the liquid to cool. This would be followed by checking with the teacher and disposing of the contents of the test tube and then disposing of the chipped test tube in the broken glass container. 21 . a) The first diagram on the left is beryllium Be. This is determined by the four dots shown representing the four electrons in a neutral beryllium atom. The second diagram from the left is carbon, C, as determined by its six electrons. The third diagram from the left is oxygen, O, as determined by the eight electrons. The diagram on the right is neon, Ne, as determined by the ten electrons shown. - Copyright © McGraw Hill Ryerson 2017 978 1 25 965137 3 -- - - 267 BC Science Connections 9 Teaching Notes Unit 2 : The electron arrangement of atoms impacts their chemical nature b) Each of these elements belongs to the same period but not the same group. They belong to the second period. You know they belong to the second period because they all have valence electrons in the second circle from the center in the diagram. c) A decrease in atomic size as you proceed from left to right across the period. 22. Diamond crystals have covalent bonds with shared electrons between the carbon atoms and sodium chloride crystals have ionic bonding with electrostatic attractions between the positive sodium ions and the negative chloride ions. 23. The chemical formula for nitrogen as it exists in air is N2. Although nitrogen exists as a molecule it is an element, not a compound. Compounds are made up of two or more different types of atoms and nitrogen molecules only contain nitrogen atoms. 24. a) Answers could include a description of the tests for the melting point, electrical conductivity, solubility, or hardness of the solids. b) Answers could include the melting point as ionic solids melt at higher temperatures than covalent solids or the electrical conductivity as ionic substances conduct electric current in solution or when melted and covalent compounds usually don't conduct electric current. 25. Sucrose dissolves well in water but you would not expect a sugar-water solution to conduct electric current because sucrose is a covalent compound and covalent compounds usually don't conduct electric current. 26. Wearing gloves made from a covalent compound, such as rubber, would help prevent an electrician from being electrocuted because covalent compounds are not good conductors of electricity. 27. a) The chemical formula for sodium fluoride is NaF. b) Sodium fluoride is an ionic compound because it is made from a metal, sodium, and a non-metal, fluorine. c) This compound should have a high melting point, be hard and brittle, and conduct electric current when liquid or dissolved. d) When sodium and fluorine react to form sodium fluoride the sodium atom loses an electron to form a 1+ ion and the fluorine gains an electron to form the 1- fluoride ion. The oppositely charged ions are attracted together to form ionic bonds. 28. Covalent compounds are also appropriately called molecular compounds because the smallest particle of a covalent compound would be a molecule of that compound. 29. - Copyright © McGraw Hill Ryerson 2017 978 1 25 965137 3 -- - - 268 Unit 2 : The electron arrangement of atoms impacts their chemical nature BC Science Connections 9 Teaching Notes Diamond Sodium Chloride Properties colourless solid, extremely hard, does not dissolve in water, does not conduct electricity colourless solid, hard and brittle, high melting point, dissolves in water, good conductor of electric current when melted or dissolved Structure carbon atoms bonded covalently in a three-dimensional network sodium ions and chloride ions attracted by opposite charges in ionic bonds arranged in a repeating pattern in a crystal lattice Composition made of carbon atoms only made of sodium and chloride ions 30. Ionic compounds such as sodium chloride, potassium iodide, sodium hydrogen carbonate, and covalent compounds such as water, sugar, and methane. a) For example, sodium chloride is a salty tasting colourless solid , which is hard and brittle and has a high melting point. It dissolves in water and is a good conductor of electric current when melted or dissolved. b) For example salt is used to flavour food. It is used on roads in the winter because it lowers the melting point of water when it is dissolved in water. 31 . a) In addition to water to rehydrate and sugar for energy, ultramarathoners need to replace the electrolytes such as potassium, sodium, and chloride they lose when they sweat. Adding extra salt to food and eating foods high in potassium such as bananas, dates, raisins, coconut, avocado, spinach, beans, lentils or potatoes should replenish their electrolytes. b) For example: small children who suffer from diarrhea or people who are exposed to high temperatures that cause excessive sweating . Both these types of conditions cause people’s bodies to lose electrolytes and require the electrolytes to be replenished to maintain health. 32. Students should discuss the four themes in terms of how different types of matter interact to create our world. Math Connections Page 179 Communicating Concepts, Question 13 : Students should estimate the actual size of the giant crystals using the photo, and then conduct online research to confirm the actual length and/or diameter. - Copyright © McGraw Hill Ryerson 2017 978 1 25 965137 3 -- - - 269