Facts about the atomic bomb

The first atomic bomb with the codename "little boy" was everything else than little... it was 3.00 meters long and had a Diameter of 0.7 meter.
The whole atomic bomb project started with the trinity test. This was the first man made nuclear explosion. The people were totally satisfied by the amazing destructive power. This was just the super weapon they were looking for. This type of bomb gets its explosion power from the nuclear fissioning of enriched uranium.
So "little boy" was actually the second atomic bomb, but it was the first one to be used against an enemy.
The nuclear core of the bomb just weight approximately 600 milligrams and exploded with a power equivalent to between 13 and 16 kilotons of TNT (estimates vary).

No one knows exactly how much people were killed. The numbers I found vary a lot. If you look at the American approximations you see relatively small numbers, but as soon as you look at some Sources with Japanese background you will find a lot huger numbers.
So I will just go with the american reports, which say that there died about 70,000 people as a direct result of the blast, and about the same number of people were injured. An even greater number died later as a result of nuclear fallout and cancer. Unborn babies died or were born with deformities.
Some scientist said to found out in the recent years that only about 700 people died in the following years of the bomb, but a lot more sources tell you about 100,000 dead people.