Question: 17 cl 35.453 what is the atomic number of this element
Answer: um Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury ( element ) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson ↑ Cl ↓ Br sulfur ← chlorine → argon Atomic number ( Z ) 17 Group , period group 17 ( halogens ) , period 3 Block p - block Element category diatomic nonmetal Electron configuration ( Ne ) 3s 3p Electrons per shell 2 , 8 , 7 Physical properties Phase ( at STP ) gas Melting point 171.