Periodic table

123456
Across
  1. 3. the second lightest atom
  2. 4. an atom with 86 electrons
  3. 6. an atom with 10 protons
Down
  1. 1. an atom with the mass of 131.29 u
  2. 2. an atom found in 1898
  3. 5. an atom with the melting point of -189.35°C