What I mean is, suppose we could somehow get a kilogram of matter and contain it safely. Now lets say we want to make a bomb using this kilogram, now, we have two ways, either store another kilogram of matter inside the bomb itself and let the matter and the antimatter touch each others when we want to bomb to detonate, or just expose the kilogram to the air and it will explode. But, my question here is simple, either of the previously mentioned ways will just allow the first particles touching each others to annihilate and sending the rest matter and antimatter in opposite ways making the reaction harder and slower to continue. I know eventually the whole kilogram will be annihilated, but it's all about reaction speed in explosives and that's the main difference between nuclear reactors and nuclear weapons. So now, is there a way to ensure that the matter and antimatter will completely annihilate each others with a high rate of reaction ?
You face exactly the same problem as the makers of the first explosives. Although these days we use explosives that react intramolecularly, the original explosives like gunpowder were made from a mixture of an oxidising agent (potassium nitrate) and a reducing agent (sulphur and charcoal). To get the gunpowder to go bang rather than fizz you had to mix the reagents extremely intimately so that the transport of the reacting molecules/atoms was faster than the explosion.
So basically you need an extremely intimate mixture of the matter and antimatter. That is going to make containment fun!