The number in parentheses is not an atomic weight. It is the mass number of one radioactive isotope of the element.
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
Nobelium was discovered in 1958 and named after Nobel, who invented explosives.
The 2019 Nobel Prize in Chemistry was awarded for the development of the lithium-ion battery, and Akira Yoshino of Japan was one of the winners.
The fifteen elements from actinium to lawrencium are called the actinoids. On the Room of the Elements table they are in the lower of the two rows set apart at the bottom.
There is no single right answer. Talking it over with someone at home is a good way to learn.