Unit 4 ~ Learning Guide Name:

Transcription

1 Unit 4 ~ Learning Guide Name: INSTRUCTIONS Complete the following practice questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test. Please print out the Formula Sheet found at the start of the course. You will need this to do assignments and tests! 4.1 NOTES: Atomic Theory and Bonding Atoms join together to form. is a single molecule of a substance o The element, oxygen, is O. The oxygen molecules we breath are O 2 Compounds are also pure substances, but are Oxygen and hydrogen are atoms/elements; H 2 O is a compound A chemical change occurs when to form new compounds. Atomic Theory Atoms are made up of smaller particles known as. Name Symbol Charge Location Relative Mass Proton p 1+ nucleus 1836 Neutron n 0 nucleus 1836 Electron e 1 area surrounding 1 Page 1 of 36

2 the nucleus The nucleus is at the of an atom. The nucleus is composed of Electrons exist in the space surrounding the nucleus called shells. # of protons = Nuclear charge = Atomic number = Organization of the Periodic Table The periodic table organizes all known elements. Elements are listed in order by Metals are on the (the transition metals range from group 3 to group 12), non-metals are on, and the metalloids form a staircase in the middle. Page 2 of 36

3 Rows of elements (across) are called. o All elements in a period have their electrons in the same general area around their nucleus Columns of elements are called o All elements in a family have similar properties, and bond with other elements in similar ways o Group 1 = o Group 2 = o Group 17 = o Group 18 = Ion Formation Atoms to form bonds. The atoms become electrically charged particles called ions. (= cations) o Some metals (multivalent) lose electrons in different ways o ie. Iron, Fe, loses either 2 (Fe2+) or 3 (Fe3+) electrons ( = anions) Atoms do this in an attempt to have the same number of valence electrons (electrons furthest from the nucleus) as the. Page 3 of 36

4 Patterns in the Periodic Table Electrons appear in in a very predictable manner. There is a maximum of electrons in the first shell, in the 2nd shell, and in the 3rd shell. The period # = # of shells in the atom. Except for the transition elements, the last digit of the group # = # of electrons in the valence shell The elements have, and are very stable. Page 4 of 36

5 Bohr Diagrams Bohr diagrams show Each shell holds a maximum number of electrons Electrons in the outermost shell are called Think of the shells as being 3D like spheres, not 2D like circles What element is this? It has = 18 electrons, and therefore 18 protons. # of electrons = # of protons (In a neutral atom) It has 3 electron shells, so it is in period 3 It has 8 electrons in the outer (valence) shell ARGON!!! Page 5 of 36

6 Forming Compounds When two atoms get close together, their. If the valence electrons can combine to form a low-energy bond, a compound is formed. Each atom in the compound attempts to have the stable number of valence electrons as the nearest noble gas. (This is stable) Metals may lose electrons and non-metals gain electrons, ( ) OR Atoms may share electrons ( ) Ionic bonds form when cations to anion. Metal + non-metal = ionic bond from Cations want to donate an electron(+) and anions want to accept more electrons(-) between two non- Covalent bonds form when metals. Non-metal + non-metal = covalent bond Electrons stay with their atom, but overlap with outer shells Ionic bonds Formed between cations (+ ions) and anions (- ions) Generally, this is a For example, lithium and oxygen form an ionic bond in the compound Li 2 O Covalent Bonds Formed between Page 6 of 36

7 Electrons are between atoms (as shown by the red electron in the examples below) Lewis Diagrams Bohr diagrams are very illustrative, but Lewis diagrams are very efficient when showing atoms and their bonding capabilities. Dots representing electrons are placed around the element symbols at the points of the compass (north, east, south, and west) Electron dots are placed singly, until the fifth electron is reached, then they are paired. Lewis diagrams make drawing ions, and ionic bonds much less work than Bohr diagrams. For positive ions, one electron dot is removed from the valence shell for each positive charge of the ion. For negative ions, one electron dot is added to each valence shell for each negative charge of the ion. Square brackets are placed around each ion to indicate transfer of electrons Lewis diagrams of covalent bonds are also very easy. Page 7 of 36

8 Like Bohr diagrams, valence electrons are drawn to show. All atoms wish to have a full valence shell The shared pairs of electrons are usually drawn as a straight line Diatomic molecules, like O 2, are also easy to draw in Lewis form 4.1 PRACTICE: Atomic Theory and Bonding 1. Complete the wordsearch, 4.1 quiz and 4.1 Check Your Understanding. 2. Why is oxygen considered an element but water is a compound? 3. Fill in the chart below. Page 8 of 36

9 Name Symbol Charge Location Relative Mass Proton Neutron Electron 4. If the number of electrons (-) and the number of protons (+) in an atom are equal, what must the overall charge in every atom be? 5. What "shape" separates metals from non-metals on the periodic table? 6. What is the name for columns and rows on the periodic table. 7. What are the names for positive and negative ions? Page 9 of 36

10 8. What is the maximum number of electrons allowed in each of the first 3 shells? Memorize this! 9. Draw a Bohr diagram for the following atoms (remember atoms are always neutral). Write the number of protons (p) and neutrons (n) on the inside of each atom. a. Boron p: n: b. Aluminum p: n: Page 10 of 36

11 c. Nitrogen p: n: d. Phosphorus p: n: Page 11 of 36

12 10. Which type of atom can form a covalent bond and which type can only form an ionic bond? 11. Draw a Bohr diagram for the following ions a. Aluminum p: n: d. Phosphorus p: n: Page 12 of 36

13 12. Draw Lewis Diagrams for the atoms and ions of the first 18 elements in the Periodic Table. If the element does not form an ion simply state no ion. The first two are done for you as an example. Hint: Ions are usually formed by losing all electrons in the Lewis diagram or gaining enough to create a full Lewis diagram. Ions are shown in brackets with the charge on the outside. Atomic Number of Element Group Number Lewis Diagram of Atom Lewis Diagram of Ion Cation or Anion? 1 1 H [H] + Cat 2 18 He No ion N/A Page 13 of 36

14 Atomic Number of Element 10 Group Number Lewis Diagram of Atom Lewis Diagram of Ion Cation or Anion? Draw Lewis structures for an N 2 molecule and the ionic compound Na 2 O. Page 14 of 36

15 4.2 NOTES: Names and Formulas of Compounds Ionic vs Covalent Ionic compounds are made up of All of the positives and negatives organize nicely. o Negative-positive o Negative-negative and positive-positive. Ionic compounds form from the inside-out as solid crystals Ionic compounds are like a solid stack of bricks! o A salt shaker contains thousands of small pieces of NaCl salt Covalent molecules. There is generally no order to the formation of covalent molecules These molecules clump together as solids, liquids or gases Covalent molecules are like a play-pit full of plastic balls o Each plastic ball = 1 covalent molecule of H 2 O o Pit full of balls = swimming pool full of water Ionic Compounds Writing formulas for ionic compounds In an ionic compound, the positive charges the negatives The ratio of positive:negative charges gives the proper formula o The ratio is always written in reduced form For example: What is the formula for magnesium phosphide? Step 1 : Find the symbol and charge for each element. Step 2: (option A) Cross down the charge from each element to the other or (option B) find the lowest common multiple of 2 and 3 is 6 Option A Page 15 of 36

16 Option B - 3Mg 2+ ions and 2P 3 ions For Example :Try the formula for calcium oxide Step 1: calcium is Ca 2+ oxygen is O 2 Step 2: option A - option B - 1Ca 2+ ion and 1 O 2 ions Ca 2 O 2, which is simplified and written as Naming Ionic Compounds Ionic compounds are composed of cations and anions. The name of an ionic compound is formed by writing as seen on the periodic table and then adding the name of the anion and changing its ending to For example, an ionic compound forms between magnesium and oxygen o The cation is the first part of the name, magnesium o The anion forms part of the ending of the name, ox ygen o Add -ide to the end of the name to form magnesium oxide. Ionic formulas are based on the ions of the atoms involved Remember the naming principles above For example, what is the name of Ca 3 N 2? o Ca, the cation, is calcium o N, the anion, is nitrogen o Drop the end of the anion and add -ide o Page 16 of 36

17 Multivalent Ionic Compounds Some transitional metals are, meaning they have more than one ion form. On the periodic table, the most common form of the ion is listed on top In the name of the compound are used following the cation to indicate which ion was used. For example, what is the formula for sulphide? This is as indicated by the (III) in the name. Once that is determined the rest is the same as naming ionic compounds. Step 1: Mn 3+ and S 2- Step 2: option A - option B - lowest common multiple, 2Mn 3+ ions and 3S 2- ions For Example: Try the name for TiF 4 Step 1: decide if we use Ti 3+ or Ti 4+ and F -, note that the 4 in the compound (TiF 4 ) crossed down from the Ti so we must have used Ti 4+. Step 2: name the multivalent metal as is on the periodic table, Titanium, add the roman numeral (IV) to indicate the charge used and then add the nonmetal, changing the ending to -ide, flouride. Ionic Compound- Polyatomic Ions Some ions, called polyatomic ions, are made up of (ironically, joined with covalent bonds). The whole group has a + or charge, not individual atoms. Polyatomics can be identified easily because the compound will have in it. eg. NaCO 3 (3 capital letters so one is polyatomic ion) What is the formula of sodium sulphate? Page 17 of 36

18 Steps remain the same as if we were creating an ionic compound but this time we see the polyatomic ion as one element instead of individuals. Step 1: find the symbols of the elements and their charges, polyatomics will be found on not the periodic table. Na + and SO 4 2- Step 2: the charges, any charge crossed down to a polyatomic must be put outside brackets as it applies to the entire polyatomic ion. The result would be Na 2 (SO 4 ) 1, but since we do not need to write the 1 it becomes What is the name of the compound KClO? Step1: Name the metal off the periodic table, K = Step 2: Find the polyatomic on the polyatomic list and write name as it is found, ClO = hypochlorite Covalent Compounds Covalent compounds, also called chemical formula to reveal the components of the molecule., rely on the Covalent compounds are made up of two or more. Names may reveal the components, but often do not Subscripts mean something different in covalent compounds o Ionic compounds subscripts show smallest between the ions in the compound o Covalent molecules have subscripts that show of atoms in the molecule Page 18 of 36

19 What is the chemical formula for the molecule ethanol? C 2 H 6 O, a name that must be memorized or looked up when needed What is the name of the molecule C 12 H 22 O 11?, aka table sugar Binary covalent compounds ( of prefixes. ) use a system Covalent compounds may have many or few atoms sharing electrons o CH 4 = methane and C 25 H 52 = o o o o Prefixes are often to indicate the number of atoms in the molecule. CO = carbon monoxide, CO 2 = carbon dioxide Write the (furthest left) first to end of the second atom s name What is the chemical formula for the molecule trinitrogen tetrachloride? Step 1: for each element, charge is not important in covalent bonding. Nitrogen = N, Chloride = Cl Step 2: Determine is represented by the prefixes, tri = 3 and tetra = 4 N 3 Cl 4 What is the name of the molecule Si 3 P 6? Step 1: Determine the name for each element from the periodic table. Step 2: Find the prefix from the number given to each. Step3: Join the prefix to each element remembering to change the ending of the second element to -ide. Page 19 of 36

20 Determining Ionic Vs Covalent BCLN SCIENCE 10 - Rev. Mar /2016 To determine whether a compound is : 1. Examine the formula or the ammonium ion Covalent compounds 2. If the compound is covalent system of naming if the compound is binary and does not start with hydrogen If there are, or it starts with H, there is probably a different, simpler name for the covalent molecule 3. If the compound is ionic Check the metal to see if it is (add a roman numeral if it is multivalent). Naming starts with the name of the metal atom. If it ends with a single non-metal, If it ends in, look up the name/formula in the polyatomic ion chart. Page 20 of 36

21 4.2 PRACTICE: Names and Formulas of Compounds 1. Complete Names and Formulas of Compounds challenge, 4.2 crossword, 4.2 Quiz, and 4.2 Check Your Understanding. 2. Determine the formula of each of the following monovalent ionic compounds. Use your periodic table to look up the charge on each ion. If you use the crossover method be careful on the third and fourth questions as you need to reduce your numbers! Compound Metal Ion Non-Metal Ion Formula lithium and selenium calcium and arsenic hafnium and sulfur aluminum and nitrogen 3. Name the following monovalent ionic compounds: Formula Name LiF CaCl2 Sc2S3 Rb2O Page 21 of 36

22 4. Determine the formula of each of the following polyatomic compounds. There is a page in your data booklet which has the names and formulas of polyatomic ions. Be careful to use brackets if and ONLY if they are needed! They are needed ONLY if you have more than one of a polyatomic ion in your compound. Compound Positive Ion Negative Ion Formula sodium and bicarbonate calcium and sulfate barium and phosphite ammonium and sulfur ammonium and phosphate 5. The names of compounds made from certain metals require roman numerals in them. What name do we give these metals? 6. When looking at your periodic table how will you recognize that a metal will require a roman numeral? Page 22 of 36

23 7. Determine the formula of each of the following multivalent ionic compounds. Be careful to always start your formula with a metal NOT a non-metal! Compound Metal Ion Non-Metal Ion Formula chromium (III) and phosphorus nickel (II) and chlorine iodine and mercury (I) lead (IV) and oxygen 8. Name the following multivalent ionic compounds. Use the work space provided to show how you determined the correct roman numeral Formula Work Name MnO MnO2 Fe2O3 Hg2S Page 23 of 36

24 9. When looking at formulas, what is the easy way to identify a polyatomic compound? 10. The names of all simple ionic compounds end in IDE. What are the two most common three letter endings for polyatomic compounds? 11. Name the following polyatomic compounds. IF and only if the metal is multivalent, be sure to include a roman numeral in the name and use the space provided to show how you determined the correct roman numeral. Formula Work Name NaOH Mg(CN)2 MnSO4 Mn(SO4)2 (NH4)3PO3 Pd(Cr2O7)2 Page 24 of 36

25 12. To do names and formulas for ionic compounds correctly you must balance your charges. This may require a little math. Do you ever need to do any math when naming or providing formulas for covalent compounds? 13. How can you recognize that you have a covalent compound instead of an ionic compound? 14. Determine the formula of each of the following covalent compounds. Name Formula trisilicon pentoxide dinitrogen tetrafluoride dihydrogen monoxide carbon monoxide 15. Name the following covalent compounds. Be careful with MONO! You should never start a name with MONO but you can have MONO in the middle of the name. Formula Name P3Cl7 BO4 Cl3I6 Si3I Page 25 of 36

26 16. For each of the following determine if the compound is ionic, has polyatomic ions or is covalent. Simply put an I, P or C in the box! Note that all compounds with polyatomic ions contain both covalent and ionic bonds. Name or Formula MgCl2 Ionic (I), Polyatomic (P) or Covalent CO2 NH4Cl diphosphorus pentaoxide magnesium bicarbonate ammonium selenide B2I2 AlF3 Fe2S3 dihydrogen dioxide ruthenium (III) nitrate Ca(NO2)2 sulfur monoxide Page 26 of 36

27 4.3 NOTES: Balancing Chemical Equations Chemical reactions result in. Chemical changes occur when new substances are created. The original substance(s), called, change into new substance(s) called. Chemical reactions can be written in different ways. A : o Nitrogen monoxide + oxygen --> nitrogen dioxide A : o 2NO(g) + O 2 (g) --> 2NO 2 (g) Coefficients (big numbers in front of compounds) - indicate the ratio of compounds in the reaction - here, there is as much NO and NO 2 than there is O 2 State of matter - Letters indicate the state of each compound (aq) = (s) = (l) = (g) = Conservation of Mass Chemical change means are created. BUT no new matter is created or destroyed; atoms are just. = Page 27 of 36

28 John Dalton, 200 years ago, realized that atoms simply rearrange themselves during chemical reactions. = The Law of Conservation of Mass In chemical reactions, atoms are Developed by Antoine Lavoisier and his wife Marie-Anne in the 1700s = Writing Chemical Equations The simplest form of chemical equation is a Not much information other than the elements/compounds involved Potassium metal + oxygen gas --> potassium oxide reactants appear on the left of the arrow and products appear on the right A skeleton equation shows the formulas of the elements/compounds K(s) + O 2 (g)--> K 2 O(s) A balanced chemical equation Balancing ensures that the number of each atom is the same on both sides of the reaction arrow Always use the smallest whole number ratio 4K(s) + O 2 (g) 2K 2 O(s) Balancing Chemical Equations Because of the Law of Conservation of Mass, we can count atoms and use math to balance the number of atoms in chemical equations. Page 28 of 36

29 Word equation: Methane + oxygen water + carbon dioxide o Skeleton equation: CH 4 (g) + O 2 (g) --> H 2 O(l) + CO 2 (g) o To balance the compounds, take note of how many atoms of each element occur on each side of the reaction arrow: 1 Carbon, 4 Hydrogen, 2 Oxygen --> 1 Carbon, 2 Hydrogen, 3 Oxygen 1 Carbon, 4 Hydrogen Oxygen --> 1 Carbon, Hydrogen, +2 Oxygen Balanced equation: CH 4 (g) + 2O 2 (g) --> 2H 2 O(l) + CO 2 (g) Balance chemical equations by following these steps: Trial and error will work, but can be very inefficient Balance, elements last Balance one compound at a time Only add coefficients; NEVER change subscripts! If appear in more than one place, attempt to balance them Polyatomic ions (such as SO 4 2 ) can often be Always double-check after you think you are finished! Balance the following: Fe + Br 2 --> FeBr 3 Sn(NO 2 ) 4 + K 3 PO 4 --> KNO 2 + Sn 3 (PO 4 ) 4 C 2 H 6 + O 2 --> CO 2 + H 2 O Page 29 of 36

30 Writing Word Equations Word equations require careful examination to be written correctly. The chemical symbol is used for most elements but not in a compound o Be careful of diatomic and polyatomic elements such as O 2, P 4 and S 8 o The special seven are all diatomic elements! Several common covalent molecules containing hydrogen have common names that do not help in writing chemical formulas o For example, methane =, glucose =, Ethane =, Ammonia = The pink shaded area in the picture below shows the diatomic atoms. Page 30 of 36

31 4.3 PRACTICE: Balancing Chemical Equations 1. Complete 4.3 wordsearch, 4.3 practice quiz, and 4.3 Check Your Understanding. 2. In a chemical reaction, what do we call the original substances? 3. In a chemical reaction, what do we call newly made substances? 4. What are the three common states of matter? 5. If the mass of all the reactants in a chemical reaction is 100g, what will the mass of all the products be? 6. Please balance the following reactions. Use the table to show your work. Mg + HCl MgCl2 + H2 Reactants Products Mg + N2 Mg3N2 Reactants Products Page 31 of 36

32 Ba + HBr BaBr2 + H2 Reactants Products BiCl3 + H2S Bi2S3 + HCl Reactants Products Br2 + KI I2 + KBr Reactants Products Page 32 of 36

33 Fe + O2 Fe3O4 Reactants Products CaO + C CaC2 + CO2 Reactants Products Bi2O3 + H2 Bi + H2O Reactants Products P4 + I2 PI3 Reactants Products Page 32 of 35

34 BCLN SCIENCE 10 - Rev. August/2014 Sn + NaOH Na2SnO2 + H2 Reactants Products C6H12O6 + O2 CO2 + H2O Reactants Products C8H18 + _O2 CO2 + H2O Reactants Products 7. What are the seven diatomic molecules? It is strongly recommended you memorize these!

35 BCLN SCIENCE 10 - Rev. August/2014 Unit 4 Learning Guide Answers **Please note that some answers for this section are directly from the notes. In such cases the page number of the webpage notes will be given. Atomic Theory and Bonding 1) Page 1, 2) Page 2, 3) Neutral or Zero, 4) Page 3, 5) Page 3, 6) Page 4, 7) 2, 8, 8, 8) 9) Covalent two non-metals, Ionic Metal and a non-metal. 10) 11) Group # - 1, 18, 1, 18, 2, 13, 14, 15, 16, 17, 18, 1, 2, 13, 14, 15, 16, 17, 18 Lewis Dot Diagrams: Lewis Dot Ions: [H] +, No ion, [Li] +, [Be] +2, No Ion, No Ion, N full shell -3 charge, O full shell -2 charge, F full shell -1 charge, No ion, [Na] +, [Mg] +2, Al full shell +3 charge, No Ion, P full shell - 3, S full shell -2, Cl full shell -1 charge, No ion. Ion type: Cat, N/A, Cat, Cat, N/A, N/A, An, An, An, N/A, Cat, Cat, An, An, An, An, An, N/A 12)

36 BCLN SCIENCE 10 - Rev. August/2014 Names and Formulas of Compounds: 2) Li 2Se, Ca 3As 2, HfS 2, AlN, 3) Lithium fluoride, Calcium chloride, Scantium sulphide, Rubidium oxide, 4) NaHCO 3, CaSO 4, Ba 3(PO 3) 2, (NH 4) 2S, (NH 4) 3PO 4, 5) Multivalent compounds, 6 ) if it has more than one ion charge, 7)CrP, NiCl 2, HgI, PbO 2, 8) Manganese(II) oxide, Manganese(IV) oxide, Iron(III) oxide, Mercury(II) sulfide, 9) the presence of brackets or the presence of more than 2 capital letters. 10) ate and ite 11) Sodium hydroxide, Magnesium cyanide, Manganese(IV) sulphate, Manganese(IV) sulphate, Ammonium phosphite, Palladium(IV) dichromate, 12) No, 13) It s made of two non-metals 14) Si 3O 5, N 2F 4, H 2O, CO, 15) triphosphorus heptachloride, Boron tetraoxide, trichlorine hexaiodide, 16) I, C, P/I/C, C, P/I/C, P/I/C, C, I, I, C, P/I/C, P/I/C, C. Balancing Chemical Equations: 2)Reactants, 3) products, 4) solid, liquid, gas, 5) 100g, 6) Mg+2HCl ---MgCl 2 + H 2 3Mg + N Mg 3N 2 Ba + 2HBr --- BaBr 2 + H 2 2BiCl 3 + 3H 2S --- Bi 2S 3 + 6HCl Br 2 + 2KI --- I 2 + 2KBr 3Fe + 2O 2 ---Fe 3O 4 2CaO + 5C ---2CaC 2 + CO 2 Bi 2O 3 + 3H Bi + 3H 2O P 4 + 6I PI 3, Sn + 2NaOH --- Na 2SnO 2 + H 2 C 6H 12O 6 + 6O CO 2 + 6H 2O, 2C 8H O CO H 2O, 7) N, O, H, Cl, Br, I, F.