How can you get determine an atomic number?
You can look at the periodic table.
The atomic number of any element is the number of protons one atom has in its nucleus. The periodic table of elements shows each element's atomic number; it is basically arranged in order of increasing atomic number.
For example, the atomic number of hydrogen (H) is 1, the atomic number of boron (B) is 5, etc.
The Atomic Number of an element defines the number of protons in the nucleus of the specified element. For Oxygen, Atomic Number is 8 which means that all Oxygen atoms have 8 protons in their nuclei. For Uranium, the Atomic Number is 92 =>