Roentgenium is a synthetic chemical element with the atomic number 111 in the periodic table. It’s a synthetically produced transuranium element that cannot| The Chemical Elements
Darmstadtium is a radioactive chemical element with an atomic number of 110 in the periodic table. Classified as transfermium, darmstadtium does not occur naturally in Earth’s crust.| The Chemical Elements
Meitnerium is a radioactive chemical element with the atomic number 109 in the periodic table. Since it’s synthetically produced, meitnerium cannot be found| The Chemical Elements