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Catalog No. AP6440 Publication No. 6440 Naming Atoms — Elements, Ions and Isotopes Student Activity Kit Introduction Use this simple and straightforward activity to help students understand the basics of a fundamental atomic concept, the nucleus and its particles. Concepts s !TOM s !TOMICNUMBER s )SOTOPE s )ON Background -ATTERISDEFINEDASANYSUBSTANCETHATHASMASSANDOCCUPIESAVOLUME!LLMATTERISEITHERAPUREELEMENTORACOMBINAtion of elements. Elements are matter that cannot be separated by chemical or physical means. Each element has its own unique properties, such as melting point, density, and the way it reacts chemically. There are 90 elements that are naturally occurring. The SMALLESTPARTOFANELEMENTTHATSTILLHASTHESESAMEPROPERTIESISCALLANATOM!LLATOMSAREMADEUPOFTHREETYPESOFPARTICLES protons, neutrons, and electrons. The number of protons in an atom is called its atomic number. Every atom of each element has exactly this number of protons. Two of these three particles possess electrical charge. The proton has a positive (+) charge, the electron has a negative (–) charge, and the neutron has no ELECTRICAL CHARGE!N ATOM ALWAYS HAS equal numbers of the positively charged protons and the negatively charged electrons, giving the atom zero electrical charge. This neutral atom has two electrons in the electron cloud. The electrons are very mobile and can range from the center of the atom to its outer edge. The best model that represents the electrons and their movement is the electron cloud model. (See Figure 1.) Protons and neutrons are always together in the center, or nucleus, of the atom. (See Figure 1.) The size of the nucleus is very Electron cloud small and very compact when compared to the size of the atom itself. In fact, as a comparison if the nucleus were the size of a golf ball, the atom’s outer edge would be 23⁄4MILESAWAY!MODELOFANATOMIS shown in Figure 1. Nucleus Neutron ++ Proton Proton Neutron Figure 1. %LECTRON#LOUD-ODELOFTHE!TOM CHEM-FAX!. . .makes science teaching easier. IN6440 081012 Though electrons have the same, but opposite, charge as that of protons, their mass is extremely small compared to the protons and neutrons, which are approximately of equal mass. The mass of the atom is therefore determined by adding together the masses of the protons and neutrons. The total number of protons and neutrons in an atom is called its atomic mass number. When two atoms have the same number of protons, but different numbers of neutrons, they are called isotopes. Since isotopes have the same number of protons, they are the same element and are identical in the ways they react. For example, atoms with 17 protons are called chlorine atoms. There are two isotopes of chlorine. One isotope has 17 protons and 18 neutrons. Its atomic number is 17 (chlorine) and its atomic mass number is 35. The isotope is written as the element name, followed by the atomic mass number. This isotope of chlorine is written chlorine–35. The other isotope of chlorine has 17 protons and 20 neutrons and is written chlorine-37. !LLTHEELEMENTSAREARRANGEDINACHARTCALLEDTHEPERIODICTABLE4HEELEMENTSARELISTEDINORDEROFINCREASINGATOMICNUMber, from left to right and top to bottom. Each element is enclosed in a box in the periodic table. The box typically contains the element name, its one- or two-letter symbol and its atomic number (Figure 2). !TOMICNUMBER 15 B Symbol Boron Name Figure 2. To determine the element name of an atom, count the number of protons and look for this atomic number on the periodic table. In chemical reactions, atoms tend to gain or lose their electrons. If an atom loses or gains electrons and now has an unequal number of protons and electrons, it is called an ion. If an atom contains 17 protons, 18 neutrons, and 18 electrons, then the atom is a chloride ion. Ions are written using the element symbol, with the net number of electrons gained or lost at the top and right of the SYMBOL)FTHEIONHASLOSTELECTRONSASIGNISPUTAFTERTHENUMBERIFTHEIONHASGAINEDELECTRONSAnSIGNISUSED)FTHEIONHAS lost or gained only one electron, the number 1 is omitted from the ion symbol. The chloride ion, with one extra electron, is written: Cl– If an atom has 20 protons and 18 electrons and the atom has lost two electrons, then the ion is a calcium atom (atomic number 20) and the electrical charge is 2+ (20 – 18 = 2). The ion is written as: Ca2+ Pre-Lab Questions (Look up elements on the periodic table on page 5.) 1. What is the element name for the following atoms. a. 6 protons, 6 neutrons, and 6 electrons. b. 18 protons, 20 neutrons, and 18 electrons. c. 3 protons, 4 neutrons, and 3 electrons. –2– IN6440 Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and retrieval system, without permission in writing from Flinn Scientific, Inc. 2. Write the isotope name for the following atoms. a. 8 protons, 8 neutrons, and 8 electrons. b. 15 protons, 16 neutrons, and 15 electrons. c. 30 protons, 36 neutrons, and 30 electrons. !NATOMHASPROTONSNEUTRONSANDELECTRONSASECONDATOMHASPROTONSNEUTRONSANDELECTRONSANDA third atom has 23 protons, 27 neutrons, and 18 electrons. a. What is the name and symbol of the element? b. What is the atomic mass number of each atom? c. What is charge on each atom? d. Write the ion. 4. Write the ions for the following atoms. a. 5 protons, 6 neutrons, and 2 electrons. b. 37 protons, 48 neutrons, and 36 electrons. c. 16 protons, 16 neutrons, and 18 electrons. Safety Precautions The materials used in this activity are considered nonhazardous. Follow all standard laboratory safety practices. Procedure !TTHELABBENCHESAREBAGSLABELED!n2%ACHBAGCONTAINSVARIOUSAMOUNTSOFBLACKANDBLUEMARBLESWITHANUMBER written on the outside of the bag. The black marbles represent protons, the blue marbles neutrons, and the written number represents the total number of electrons. 2. For each bag, record the number of protons, neutrons, and electrons in the Data Table. 3. Using these values and the periodic chart, deduce the information needed to complete the Data Table for each bag. If the atom is an ion, write its symbol in the “Ion Symbol” column. –3– IN6440 Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and retrieval system, without permission in writing from Flinn Scientific, Inc. Name: ___________________________________ Data Table Bag # of Protons # of Neutrons Mass Number Element # of Electrons Element Symbol Ion Symbol Isotope Symbol # of Protons # of Neutrons Mass Number Element # of Electrons Element Symbol Ion Symbol Isotope Symbol # of Protons # of Neutrons Mass Number Element # of Electrons Element Symbol Ion Symbol Isotope Symbol ! B C D E F Bag G H I J K L Bag M N O P Q 2 –4– IN6440 Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and retrieval system, without permission in writing from Flinn Scientific, Inc. Ú&LINN3CIENTIFIC)NC!LL2IGHTS2ESERVED2EPRODUCTIONPERMISSIONISGRANTEDONLYTOSCIENCETEACHERSWHOHAVEPURCHASED.AMING!TOMS#ATALOG.O!0FROM&LINN3CIENTIFIC)NC No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and retrieval system, without permission in writing from Flinn Scientific, Inc. –5– IN6440 H 2 4 1 3 12 9.012 20 19 21 3 IIIB 22 4 IVB 23 5 VB 24 6 VIB 25 7 VIIB 26 8 27 9 VIIIB 28 10 29 11 IB 30 12 IIB B C 12.01 14 6 14 IVA 31 26.98 32 28.09 Al Si 13 10.81 5 13 IIIA P 33 30.97 10 9 19.00 17 20.18 18 F Ne 18 4.003 VIIIA 17 VIIA He 2 34 32.07 35 35.45 36 39.95 S Cl Ar 16.00 16 8 16 VIA N O 14.01 15 7 15 VA The Periodic Table of the Elements 40 39 38 56 55 88 87 (223) Lithium Li # # Ac–Lr 89–103 ★ La–Lu 57–71 88.91 © 2012 Flinn Scientific, Inc. Name Symbol 3 (226) Fr Ra 137.3 132.9 Cs Ba 87.62 85.47 58 57 59 (271) 106 183.8 60 (272) 107 186.2 75 (98) 61 (270) 108 190.2 76 101.1 44 55.85 62 (276) 109 192.2 77 102.9 45 58.93 195.1 110 78 106.4 46 58.69 197.0 111 79 107.9 47 63.55 200.6 112 80 112.4 48 65.38 204.4 113 81 114.8 49 69.72 207.2 114 82 118.7 50 72.64 209.0 115 83 121.8 51 74.92 (209) 116 84 127.6 52 78.96 I (210) 117 85 126.9 53 79.90 (222) 118 86 131.3 Xe 54 83.80 63 (281) 64 (280) 65 (285) 66 (284) 67 (289) 68 (288) (294) 71 (294) 70 (293) 69 140.1 90 140.9 91 144.2 92 (145) 93 150.4 94 152.0 95 157.3 96 158.9 97 162.5 98 164.9 99 167.3 100 168.9 101 173.0 102 175.0 103 (227) 232.0 231.0 238.0 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (262) Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 138.9 89 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu (268) (267) 105 180.9 74 95.96 43 54.94 Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo 104 178.5 73 92.91 42 52.00 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 72 91.22 41 50.94 Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 47.87 44.96 40.08 Rb Sr Y 39.10 37 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 24.31 22.99 Na Mg 6.941 11 Li Be IIA IA 1.008 Atomic Number 7 6 5 4 3 2 1 1