Write the atomic number of the element present in the third period and seventeenth group of the periodic table.
Solution and Explanation
There are two elements in the \(1^{st}\) period and eight elements in the \(2 ^{nd}\) period. The third period starts with the element with \(Z = 11\). Now, there are eight elements in the third period. Thus, the 3rd period ends with the element with \(Z = 18\) i.e., the element in the \(18^{th}\) group of the third period has \(Z = 18\).
Hence, the element in the \(17^{th}\) group of the third period has atomic number \(Z = 17\).
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Concepts Used:
Modern Periodic Table
Modern Periodic Table is the tabular arrangement of the elements in increasing order of their atomic numbers. It is commonly referred to as the Long Form of the Periodic Table and is based on the modern periodic law and is the tabular arrangement of elements in increasing order of their atomic numbers (Z).
*Numbering system adopted by the International Union of Pure and Applied Chemistry (IUPAC).
- The elements in the same group of the Modern Periodic Table have the same valence electron configuration and thus have similar chemical properties.
- The elements in the same period of the Modern Periodic Table will have an increasing order of valence electrons. Hence, the number of energy sub-levels per energy level increases as the energy level of the atom increases.
The periodic table of elements is as follows:
| Atomic number (Z) | Symbol | Name |
| 1 | H | Hydrogen |
| 2 | He | Helium |
| 3 | Li | Lithium |
| 4 | Be | Beryllium |
| 5 | B | Boron |
| 6 | C | Carbon |
| 7 | N | Nitrogen |
| 8 | O | Oxygen |
| 9 | F | Fluorine |
| 10 | Ne | Neon |
| 11 | Na | Sodium |
| 12 | Mg | Magnesium |
| 13 | Al | Aluminium |
| 14 | Si | Silicon |
| 15 | P | Phosphorus |
| 16 | S | Sulfur |
| 17 | Cl | Chlorine |
| 18 | Ar | Argon |
| 19 | K | Potassium |
| 20 | Ca | Calcium |
| 21 | Sc | Scandium |
| 22 | Ti | Titanium |
| 23 | V | Vanadium |
| 24 | Cr | Chromium |
| 25 | Mn | Manganese |
| 26 | Fe | Iron |
| 27 | Co | Cobalt |
| 28 | Ni | Nickel |
| 29 | Cu | Copper |
| 30 | Zn | Zinc |
| 31 | Ga | Gallium |
| 32 | Ge | Germanium |
| 33 | As | Arsenic |
| 34 | Se | Selenium |
| 35 | Br | Bromine |
| 36 | Kr | Krypton |
| 37 | Rb | Rubidium |
| 38 | Sr | Strontium |
| 39 | Y | Yttrium |
| 40 | Zr | Zirconium |
| 41 | Nb | Niobium |
| 42 | Mo | Molybdenum |
| 43 | Tc | Technetium |
| 44 | Ru | Ruthenium |
| 45 | Rh | Rhodium |
| 46 | Pd | Palladium |
| 47 | Ag | Silver |
| 48 | Cd | Cadmium |
| 49 | In | Indium |
| 50 | Sn | Tin |
| 51 | Sb | Antimony |
| 52 | Te | Tellurium |
| 53 | I | Iodine |
| 54 | Xe | Xenon |
| 55 | Cs | Caesium |
| 56 | Ba | Barium |
| 57 | La | Lanthanum |
| 58 | Ce | Cerium |
| 59 | Pr | Praseodymium |
| 60 | Nd | Neodymium |
| 61 | Pm | Promethium |
| 62 | Sm | Samarium |
| 63 | Eu | Europium |
| 64 | Gd | Gadolinium |
| 65 | Tb | Terbium |
| 66 | Dy | Dysprosium |
| 67 | Ho | Holmium |
| 68 | Er | Erbium |
| 69 | Tm | Thulium |
| 70 | Yb | Ytterbium |
| 71 | Lu | Lutetium |
| 72 | Hf | Hafnium |
| 73 | Ta | Tantalum |
| 74 | W | Tungsten |
| 75 | Re | Rhenium |
| 76 | Os | Osmium |
| 77 | Ir | Iridium |
| 78 | Pt | Platinum |
| 79 | Au | Gold |
| 80 | Hg | Mercury |
| 81 | Tl | Thallium |
| 82 | Pb | Lead |
| 83 | Bi | Bismuth |
| 84 | Po | Polonium |
| 85 | At | Astatine |
| 86 | Rn | Radon |
| 87 | Fr | Francium |
| 88 | Ra | Radium |
| 89 | Ac | Actinium |
| 90 | Th | Thorium |
| 91 | Pa | Protactinium |
| 92 | U | Uranium |
| 93 | Np | Neptunium |
| 94 | Pu | Plutonium |
| 95 | Am | Americium |
| 96 | Cm | Curium |
| 97 | Bk | Berkelium |
| 98 | Cf | Californium |
| 99 | Es | Einsteinium |
| 100 | Fm | Fermium |
| 101 | Md | Mendelevium |
| 102 | No | Nobelium |
| 103 | Lr | Lawrencium |
| 104 | Rf | Rutherfordium |
| 105 | Db | Dubnium |
| 106 | Sg | Seaborgium |
| 107 | Bh | Bohrium |
| 108 | Hs | Hassium |
| 109 | Mt | Meitnerium |
| 110 | Ds | Darmstadtium |
| 111 | Rg | Roentgenium |
| 112 | Cn | Copernicium |
| 113 | Nh | Nihonium |
| 114 | Fl | Flerovium |
| 115 | Mc | Moscovium |
| 116 | Lv | Livermorium |
| 117 | Ts | Tennessine |
| 118 | Og | Oganesson |
Read More: Periodic Classification of Elements