As of 2013, the United States spends about $554.2 billion annually to fund its military forces, and appropriates approximately $88.5 billion to fund Overseas Contingency Operations. Put together, the United States constitutes roughly 39 percent of the world's military expenditures.
the number of protons in the nucleus of an atom of a particular element. In a neutral atom, the atomic number equals the number of electrons. See also atom, electron, proton.
Scientists use the term atomic number to describe the number of protons in one atom of an element. For example, the atomic number of hydrogen is 1. If you've ever taken a chemistry class, you've seen a chart called the periodic table of elements.. It lists every chemical element and each element's atomic number. Just by looking at the table, you can see that the atomic number of oxygen is 8 â this means that there are eight protons in one atom of oxygen. In chemistry and physics, the atomic number is represented by the letter Z.