Since we cannot really look at something as small as an atom (actually, with the most powerful kind of microscope, it is just barely possible to get a picture of an individual atom, which looks like a tiny blob) we use very complicated mathematical models to tell us about the shape of an atom. The most complete mathematical description of the behavior of sub-atomic particles is the Shroedinger Equation, which is extremely difficult to solve, so we can only get a complete answer in relatively simple cases.
The VSEPR (Valence Shell Electron Pair Repulsion) model is commonly used to determine molecular shape. This model is based on the idea that electron pairs in the valence shell of an atom repel each other and thus orient themselves in a way that minimizes repulsion to give the molecule its shape.
They are on the outside of the atom. (Apex 2021)
Mass of an atom is determined by the no. of protons+ no. of neutrons in the atom.
angles
The number of protons determine which element an atom is and normally the number of electrons is equal to it. Strip an electron off an iron atom and you have an ionised iron atom.
Proton + Nuetron = Atomic Mass
If you mean it by its atomic shape, its a hydrogen atom at both sides and an oxygen atom in the middle. But if you mean it by its normal appearance, then it can take up any shape.
round shape
All atoms are a fuzzy, indistinct shape.
electrons
Protons determine which element an atom is.
They are on the outside of the atom. (Apex 2021)