© UCLES 2021 21 0620/11/M/J/21 calcium 40 38 Sr strontium 88 56 Ba barium 137 88 potassium 39 37 Rb rubidium 85 55 Cs caesium 133 87 22 cerium 140 90 Th thorium 232 lanthanum 139 89 Ac actinium – 231 protactinium Pa 91 141 praseodymium Pr 59 58 Ce 57 – dubnium Db 105 181 tantalum Ta 73 93 niobium Nb 41 51 vanadium V – rutherfordium Rf 104 178 hafnium Hf 72 91 zirconium Zr 40 48 titanium La lanthanoids 57–71 89 yttrium Y 39 45 scandium Ti 23 Cr 24 238 uranium U 92 144 neodymium Nd 60 – seaborgium Sg 106 184 tungsten W 74 96 molybdenum Mo 42 52 chromium relative atomic mass – neptunium Np 93 – promethium Pm 61 – bohrium Bh 107 186 rhenium Re 75 – technetium Tc 43 55 manganese Mn 25 – plutonium Pu 94 150 samarium Sm 62 – hassium Hs 108 190 osmium Os 76 101 ruthenium Ru 44 56 iron Fe 26 27 28 29 30 – americium Am 95 152 europium Eu 63 – meitnerium Mt 109 192 – curium Cm 96 157 gadolinium Gd 64 – darmstadtium Ds 110 195 platinum Pt Ir iridium 78 106 palladium Pd 46 59 nickel Ni 77 103 rhodium Rh 45 59 cobalt Co – berkelium Bk 97 159 terbium Tb 65 – roentgenium Rg 111 197 gold Au 79 108 silver Ag 47 64 copper Cu – californium Cf 98 163 dysprosium Dy 66 – copernicium Cn 112 201 mercury Hg 80 112 cadmium Cd 48 65 zinc Zn B C – einsteinium Es 99 165 holmium Ho 67 204 thallium Tl 81 115 – fermium Fm 100 167 erbium Er 68 – flerovium Fl 114 207 lead Pb 82 119 tin Sn In indium 50 73 germanium Ge 32 28 silicon Si 14 12 carbon 49 70 gallium Ga 31 27 aluminium Al 13 11 boron 6 – mendelevium Md 101 169 thulium Tm 69 209 bismuth Bi 83 122 antimony Sb 51 75 arsenic As 33 31 phosphorus P 15 14 nitrogen N 7 – nobelium No 102 173 ytterbium Yb 70 – livermorium Lv 116 – polonium Po 84 128 tellurium Te 52 79 selenium Se 34 32 sulfur S 16 16 oxygen O 8 – lawrencium Lr 103 175 lutetium Lu 71 – astatine At 85 127 iodine I 53 80 bromine Br 35 35.5 chlorine Cl 17 19 fluorine F 9 – radon Rn 86 131 xenon Xe 54 84 krypton Kr 36 40 argon Ar 18 20 neon Ne 10 4 5 helium VIII 1 VII hydrogen VI 2 V He IV 1 III H The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinoids lanthanoids – Ca K – actinoids 20 19 Ra 24 23 radium magnesium sodium Fr Mg Na francium 89–103 12 11 Sc 9 7 name atomic symbol Be beryllium Li lithium atomic number 4 3 Key II I Group The Periodic Table of Elements 16