I am an engineering researcher at the University of California-Santa Barbara. Thank you for your question “Do all atoms have the same number of protons?”

All atoms, in fact, do not have the same number of protons. All atoms of the same element—whether it is a hydrogen, helium, carbon, or oxygen atom—will have the same number of protons, but atoms of different elements will have different number of protons. For example, all hydrogen atoms have 1 proton, all helium atoms have 2 protons, all carbon atoms have 6 protons, and all oxygen atoms have 8 protons. The number of protons that an element has is called the “atomic number”. Elements are arranged in order on a chart called the periodic table according to their atomic number. I have attached a link to a periodic table, which contains all the elements. You can see the name of the element in each square, and in the top right of each square is that element’s atomic number.

I hope this helps with your question!