Title: Period 5 element
Content:  Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible other metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two. Indium was discovered in 1863 and named for the indigo blue line in its spectrum that was the first indication of its existence in zinc ores, as a new and unknown element. The metal was first isolated in the following year. Zinc ores continue to be the primary source of indium, where it is found in compound form. Very rarely the element can be found as grains of native (free) metal, but these are not of commercial importance. Indium's current primary application is to form transparent electrodes from indium tin oxide in liquid crystal displays and touchscreens, and 
Title: Period 5 element
Content:  || d-block || [Kr] 4d5 5s2 ; - bgcolor="" ; 44 || Ru || Ruthenium || d-block || [Kr] 4d7 5s1 (*) ; - bgcolor="" ; 45 || Rh || Rhodium || d-block|| [Kr] 4d8 5s1 (*) ; - bgcolor="" ; 46 || Pd || Palladium || d-block || [Kr] 4d10 (*) ; - bgcolor="" ; 47 || Ag || Silver || d-block || [Kr] 4d10 5s1 (*) ; - bgcolor="" ; 48 || Cd || Cadmium || d-block || [Kr] 4d10 5s2 ; - bgcolor="" ; 49 || In || Indium || p-block || [Kr] 4d10 5s2 5p1 
Title: Indium
Content:  Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts per million of the Earth's crust. Indium has a melting point higher than sodium and gallium, but lower than lithium and tin. Chemically, indium is similar to gallium and thallium, and it is largely intermediate between the two in terms of its properties. Indium was discovered in 1863 by Ferdinand Reich and Hieronymous Theodor Richter by spectroscopic methods. They named it for the 
Title: Indium
Content:  the pair of 5s-electrons are not donated, resulting in indium(I), In+. The stabilization of the monovalent state is attributed to the inert pair effect, in which relativistic effects stabilize the 5s-orbital, observed in heavier elements. Thallium (indium's heavier homolog) shows an even stronger effect, causing oxidation to thallium(I) to be more probable than to thallium(III), whereas gallium (indium's lighter homolog) commonly shows only the +3 oxidation state. Thus, although thallium(III) is a moderately strong oxidizing agent, indium(III) is not, and many indium(I) compounds are powerful reducing agents. While the energy required to include the s-electrons in chemical bonding is lowest for indium among the group 13 metals, bond energies decrease down the group so that by indium, the energy released in forming two additional bonds and attaining the +3 state is not 
Title: Indium
Content:  Indium has 39 known isotopes, ranging in mass number from 97 to 135. Only two isotopes occur naturally as primordial nuclides: indium-113, the only stable isotope, and indium-115, which has a half-life of 4.41 years, four orders of magnitude greater than the age of the Universe and nearly 30,000 times greater than that of natural thorium. The half-life of 115In is very long because the beta decay to 115Sn is spin-forbidden. Indium-115 makes up 95.7% of all indium. Indium is one of three known elements (the others being tellurium and rhenium) of which the stable isotope is less abundant in 
Title: 53 (number)
Content: The atomic number of iodine 
Title: Period 5 element
Content:  The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning with rubidium and ending with xenon. As a rule, period 5 elements fill their 5s shells first, then their 4d, and 5p shells, in that order; however, there are exceptions, such as rhodium.
Title: Period 5 element
Content: {| class="wikitable sortable" - bgcolor="" ; 37 || Rb || Rubidium || s-block || [Kr] 5s1 ; - bgcolor="" ; 38 || Sr || Strontium || s-block || [Kr] 5s2 ; - bgcolor="" ; 39 || Y || Yttrium || d-block || [Kr] 4d1 5s2 ; - bgcolor="" ; 40 || Zr || Zirconium || d-block || [Kr] 4d2 5s2 ; - bgcolor="" ; 41 || Nb || Niobium || d-block || [Kr] 4d4 5s1 (*) ; - bgcolor="" ; 42 || Mo || Molybdenum || d-block || [Kr] 4d5 5s1 (*) ; - bgcolor="" ; 43 || Tc || 
Title: Period 5 element
Content:  - bgcolor="" ; 50 || Sn || Tin || p-block || [Kr] 4d10 5s2 5p2 ; - bgcolor="" ; 51 || Sb || Antimony || p-block || [Kr] 4d10 5s2 5p3 ; - bgcolor="" ; 52 || Te || Tellurium || p-block || [Kr] 4d10 5s2 5p4 ; - bgcolor="" ; 53 || I || Iodine || p-block || [Kr] 4d10 5s2 5p5 ; - bgcolor="" ; 54 || Xe || Xenon || p-block || [Kr] 4d10 5s2 5p6 ; } ! colspan="3" | Chemical element ! Block ! Electron configuration ! !!!! (*) Exception to the Madelung rule
Title: Indium
Content:  Indium is a silvery-white, highly ductile post-transition metal with a bright luster. It is so soft (Mohs hardness 1.2) that like sodium, it can be cut with a knife. It also leaves a visible line on paper. It is a member of group 13 on the periodic table and its properties are mostly intermediate between its vertical neighbours gallium and thallium. Like tin, a high-pitched cry is heard when indium is bent – a crackling sound due to crystal twinning. Like gallium, indium is able to wet glass. Like both, indium has a low melting point, 156.60 °C (313.88 °F); 

Question: the atomic number of indium which belongs to 5th period is?
Answer: 49.