Determining Ion Charges and Identifying Elements in the Periodic Table, Study notes of Chemistry

Download Determining Ion Charges and Identifying Elements in the Periodic Table and more Study notes Chemistry in PDF only on Docsity! The Nuclear Model of the Atom: ¢ The atom is composed of protons and neutrons, which compose most of the atom’ s mass and are grouped together in a dense nucleus. ¢ Electrons comprise most of the atom’ s volume. ¢ Protons and neutrons have similar masses (1 amu), while electrons have a much smaller mass. 6 protons +6 neutrons e electron b proton Qe neutron Carbon atom Charge:'' ' •  Protons'and'electrons'both'have'electrical'charge.'' •  The'charge'of'the'proton'is'1+'and'the'charge'of'the' electron'is'1
.'' •  The'neutron'has'no'charge.'' •  When'protons'and'electrons'combine'in'atoms,'their' charges'cancel.' •  Many'of'the'machines'and'computers'we'depend'on' are'powered'by'electricity,'which'is'the'movement'of' electrical'charge.' CaVons! •  A!caFon!forms!when!an!atom!loses! one!or!more!electrons!from!its!outer! (valence)!shell!(energy!level).! •  CaVons!are!posiVvely!charged! because!the!atom!has!more!protons! (+)!than!electrons!(–).! –  Mg!atom!has!12!protons!and!12! electrons.! –  Mg+2!ion!has!12!protons!and!10! electrons.! •  Metal!elements!tend!to!form!caVons.! ! •  Example !!! –  Mg!"!Mg2+!+!2!e–! Anions' •  An!anion'forms!when!an!atom!gains! one!or!more!electrons!into!its!outer! (valence)!shell!(energy!level).! •  Anions!are!negaVvely!charged! because!the!atom!has!less!protons! (+)!than!electrons!(–).! –  F!atom!has!9!protons!and! 9!electrons.! –  F–!ion!has!9!protons!and!10! electrons.! •  Nonmetal!elements!tend!to!form! anions.! •  Example !! –  F!!+!!e–!!"!!F–! ! The periodic table indicates that the atomic number for calcium is 20, so calcium has 20 protons. You can find the number of electrons using the ion charge equation. Ion charge = #p+ – #e– Determining the Number of Protons and Electrons in an Ion Determine the number of protons and electrons in the Ca2+ ion. SOLUTION Ion!charge!=!#p+!–!#e–! 2+!=!20!–!#e–! #e–!=!20!–!2!=!18! The!number!of!electrons!is!18.! The!Ca2+!ion!has!20!protons!and! 18!electrons.! Determining the Number of Protons and Electrons in an Ion Determine the number of protons and electrons in the S2– ion. Answer:(16 protons, 18 electrons Determining Ion Charge from Numbers of Protons and Electrons Determine the charge of each ion. (a)  a magnesium ion with 10 electrons (Magnesium’s!atomic!number!is!12) (b) a sulfur ion with 18 electrons (Sulfur’s atomic number is 16) (c) an iron ion with 23 electrons (Iron’s atomic number is 26) SOLUTION ' To!determine!the!charge!of!each!ion,!use!the!ion!charge!equaVon.! ! Ion!charge!=!#p+!–!#e–! ! You!are!given!the!number!of!electrons!in!the!problem.!You!can!obtain!the!number!of!protons!from!the!element’s! atomic!number!in!the!periodic!table.! ' (a) ''Ion!charge!=!12!–!10!=!2!+!(Mg2+)! ! (b)  Ion!charge!=!16!–!18!=!2!–!(S2–)! (c)  Ion!charge!=!26!–!23!=!3!+!(Fe3+)! ! ! ! Periodic!Table:!Historic!perspecVve! •  Dmitri!Mendeleev!(1834–1907)! developed!the!modern!periodic!table.! ! •  Periodic'law'' –  When'the'elements'are'arranged'in' order'of'increasing'atomic'mass,' certain'sets'of'properFes'recur' periodically.' –  Elements!having!similar!physical!and! chemical!properVes!fall!within!a! column.! ! •  We!now!know!that!element!properVes! are!periodic!funcVons!of!their!atomic' numbers.! Periodic!Table:!OrganizaVon! •  The!elements!are!arranged!from!lec!to!right!in!increasing! atomic'number'(number!of!protons!an!element!has).! •  Rows!in!the!periodic!table!are!referred!to!as!periods.! •  Columns!within!the!periodic!table!are!someVmes!referred!to!as! families.! –  Because!the!elements!within!the!column!have!similar! physical!and!chemical!properVes! ! •  The!elements,!their!names,!and!symbols!are!given!on!the! periodic'table.! The periodic table groups many different elements together according to their properties In main group elements, properties can generally be predicted based on the element’s position. In transition elements, properties tend to be less predictable based on the element’s position. a The numbering across the top of the periodic table is important ain- group elements Transition elements Main-group elements Group 1 ae 8A 1 2A 3A 4A 5A 6A 7A 2 3 8B ns 3B 4B 5B 6B 7B ———~—— 1B 2B 8 4 21 22 23) 24 25 26 af 28 29 30 5 Sc | Ti Vv Cr | Mn} Fe | Co} Ni | Cu} Zn a 5 39 40 41 42 43 44 45 46 47 48 Y | Zr | Nb | Mo} Tec | Ru | Rh | Pd | Ag | Cd 6 57 72 73) 74 75 76 77 78 79 80 La | Hf | Ta | W | Re |} Os |] Ir Pt | Au | Hg 7 89 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 } 112 Ac | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn **Element 117 is currently under review by IUPAC. Periodic!Table:!Metals! •  CharacterisVcs! ! –  Solid!at!room!temperature!(except!Hg)! –  ReflecVve!surface! •  Shiny! –  Conduct!heat!and!electrical!current! –  Malleable! •  Can!be!shaped! –  DucVle! –  Lose!electrons!and!form!caVons! –  About!75%!of!the!elements!in!the!periodic!table!are!metals.! Periodic!Table:!Metalloids!(semimetals)! •  CharacterisVcs! ! –  Can!exhibit!the!properVes!of!metals!and/ or!nonmetals! –  Known!as!semiconductors! •  intermediate!electrical!conducVvity,! which!can!be!changed!and!controlled! #  This!property!makes!semiconductors!useful!in!the! manufacture!of!electronic!devices!that!are!central! to!computers,!cell!phones,!and!other!modern! gadgets.!! –  Solids!at!room!temperature! Periodic Table: Nonmetals Characteristics — Can be found in all three states (gas, liquid, and solid) of matter — Poor conductors of heat and electricity — Solids are brittle. -— Gain electrons to become anions — Except for H, found mostly in the upper right on the periodic table Families:!Grouping!of!the!Periodic!Table! •  Elements!within!a!column!are!considered!“families.”! –  They!have!similar!chemical!and!physical!properVes.! ! •  Families!of!the!periodic!table! –  Alkali!metals!(column!1/Group!number!1A)! –  Alkaline!earth!metals!(column!2/Group!number!2A)! –  Chalcogens!(column!16/Group!number!6A)! –  Halogens!(column!17/Group!number!7A)! –  Noble/inert!gases!(column!18/Group!number!8A)! Periodic Table: Families According to the periodic law, the properties of elements in a group have significant similarities. This is why some of the groups have their own names slab Noble metals gases Alkaline Chalcogens | earth metals Halogens 1A 8A 1 Group nukybers | 2 H 2A 3A 4A 5A 6A 7A | He 3 4 5 6 7 8 9 10 Li | Be B Ic N Oo FE Ne M1 | 12 Transition metals 13 | 14 | 15 | 16 | 17 | 18 Na | Mg |; | Al | Si ir Ss cl | Ar 19 20 | 21 22) 2s 24 25) 26 27 | 28 29 30 31 32 Bo) 34 | 35 36 K | Ca | Sc } Ti V | Cr | Mn} Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 Rb | Sr | Y | Zr | Nb | Mo} Tec | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te I Xe 55 | 56 | 57 || 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 Cs | Ba | La || Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg! Tl | Pb | Bi | Po | At | Rn 87 | 88 | 89 || 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114 | 115 | 116 | 117 | 118 Fr | Ra | Ac || Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg |} Cn Fl Lv | * _ [58 | 59 | 60 | 61 | 62 | 63 | 64 | 6 | 66 |] 67 | & | 9 |] | 71 Lanthanides | ce | Pr | Nd | Pm| Sm| Eu | Gd| Tb | Dy | Ho | Er | Tm| Yb | Lu Actini 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 |) 101 | 102 | 103 elamudes Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr **Element 117 is currently under review by IUPAC. Periodic table of the elements by the group name Alkeli metals Alkaline earth metals Looking for Patterns: Halogens * The halogens include fluorine, chlorine bromine, iodine, and astatine. * Highly reactive, especially with alkali metals and alkaline earth metals •  The!noble!gases! include!helium!(used! in!balloons),!neon! (used!in!neon!signs),! argon,!krypton,!and! xenon.! ! •  They!are!all! odorless,!colorless,! gases!with!very!low!!!!!!!! chemical!reacVvity! Looking'for'Pa>erns:'Noble'Gases' fos Group 16 - The Chalcogens Oxygen ALL OF THE rT ee ee |acuor THe | OXYGEN 1 pee ee OXYGEN SELENIUM TELLURIUM SOLID MAKES U Pp co OU oS ° iS} 29°C 22r°C 450°C HYDROGEN WITH Sulphur CHALCOGENS 0 CHALCOGENS 2 ARE SOFT 6 5 % AND ARE TOXIC OF THE 34 DONT CONDUCT | HUMAN BODY Se sun Pa. HEAT WELL]___ SSS arene ALLOTROPES OXYGEN)(SULPHUR) | APART FROM WATER NINE TWENTY io x we SEN 0, 0, 0, 0, S, 8, 8, S, @ oes CHALCOGEN IX VA aes sorta) = ad E SELENIUM)(POLONIUM)| SELENIUM, ELECTRONS FIVE || Two || TELLURIUM & MAINLY Se, || a-Po&8-Po| | FOL ONIN UM @ syed ALL THE GROUP 16 ELEMENTS METALLOIDS Po F ORM - 2 1 On §s USES OF THE CHALCOGENS etm WHEN REACTING WITH : ELECTROPOSITIVE METALS @ 116 SULPHUR DIOXIDE OXYGEN SULPHUR SELENIUM | TELLURIUM | POLONIUM Lv REACTS WITH WATER VAPOUR é secwoen'| paseccceans | Coss TO FORM SULPHURIC ACID AND CAUSE ACID RAIN Te Livermorium 1. To which group or family of elements does each element belong? (a) Mg (b) N (c) K (d) Br SOLUTION (a) 'Mg!is!in!Group!2A;!it!is!an!alkaline!earth!metal.! (b) 'N!is!in!Group!5A.! (c) 'K!is!in!Group!1A;!it!is!an!alkali!metal.! (d)  Br!is!in!Group!7A;!it!is!a!halogen.! 2. To which group or family of elements does each element belong? (a) Li (b) B (c) I (d) Ar ! Answers:(((a) alkali metal, Group 1A (b) Group 3A (c) halogen, Group 7A (d) noble gas, Group 8A ! GROUPS AND FAMILIES OF ELEMENTS •  All!atoms!of!a!given!element!have!the!same! number!of!protons.! •  They!do!not!necessarily!have!the!same! number!of!neutrons.!! •  Atoms!with!the!same!number!of!protons!but! different!numbers!of!neutrons!are!called! isotopes.' •  All!elements!have!their!own!unique!percent! natural'abundance!of!isotopes.!!! Isotopes:'When'the'Number'of'Neutrons'Varies! Isotopes: Natural Abundance of Isotopes in Neon Isotopes of neon Naturally occurring neon contains three different isotopes: Ne-20 (with 10 protons and 10 neutrons), Ne-21 (with 10 protons and 11 neutrons), and Ne-22 (with 10 protons and 12 neutrons). 0.27% fo25% 90.48% ATOMIC NUMBERS, MASS NUMBERS, AND ISOTOPE SYMBOLS 1. What are the atomic number (Z), mass number (A), and symbols of the carbon isotope that has 7 neutrons? SOLUTION You can determine that the atomic number (Z) of carbon is 6 (from the periodic table). This means that carbon atoms have 6 protons. The mass number (A) for the isotope with 7 neutrons is the sum of the number of protons and the number of neutrons. A = 6 + 7 = 13 So, Z = 6, A = 13, and the symbols for the isotope are C-13 and 2. What are the atomic number, mass number, and symbols for the chlorine isotope with 18 neutrons? Answer:(Z!=!17,!A!=!35,!ClG35,!and!!!!!!!! . 1. How many protons, electrons and neutrons are in the chromium isotope 2. How many protons and neutrons are in the potassium isotope Answer:(19!protons,!20!neutrons! ' NUMBERS'OF'PROTONS'AND'NEUTRONS'FROM ISOTOPE SYMBOLS SOLUTION #p+ = Z = 24 #n!=!A!–!Z! =!52!–!24! =!28! The number of protons is equal to Z (lower left number). The number of neutrons is equal to A (upper left number) –!Z (lower left number). Atomic Mass: The Average Mass of an Element’ s Atoms ¢ The atomic mass of each element listed in the periodic table represents the average mass of the atoms that compose that element. ¢ Naturally occurring chlorine consists of 75.77% chlorine-35 (mass 34.97 amu) and 24.23% chlorine-37 (mass 36.97 amu). ¢ Its atomic mass is the following: Atomic mass = (0.7577 X 34.97 amu) + (0.2423 X 36.97 amu) = 35.45 amu •  Convert!the!percent!natural!abundances!into!decimal! form!by!dividing!by!100.! SoluFon:! •  FracVon!GaG69!=!60.11!=!0.6011! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !100! •  FracVon!GaG71!=!39.89!=!0.3989! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !100! Example'SoluFon:'CalculaFng'Atomic'Mass'of'Gallium! •  Use!the!fracVonal!abundances!and!the!atomic!masses! of!the!isotopes!to!compute!the!atomic!mass!according! to!the!atomic!mass!definiVon!given!earlier.!! Atomic mass = (0.6011 × 68.9256 amu) + (0.3989 × 70.9247 amu) = 41.4321 amu + 28.2919 amu = 69.7231 amu = 69.72 amu Example'SoluFon:'CalculaFng'Atomic'Mass'of'Gallium! •  The!nuclei!of!some!isotopes!of!a!given!element! are!not!stable.!! •  These!atoms!emit!a!few!energeVc!subatomic! parVcles!from!their!nuclei!and!change!into! different!isotopes!of!different!elements.!! •  The!emiaed!subatomic!parVcles!are!called! nuclear'radiaFon.' •  The!isotopes!that!emit!! !!!!them!are!termed!! ''''radioacFve.!! Some'Isotopes'Are'RadioacFve'