Wavelengths, especially those of light, are much larger than the size of an atom. Everything we are able to observe is by the reflection of lightwaves off of an object. Because atoms are so much smaller than these waves they aren’t able to reflect them or be detected through optical microscopes.

Scientists haven’t found a way to determine or the exact location or momentum of an electron. They predict the probability distribution on where it is likely to be. This has been depicted in a few different ways.

Orbital – A mathematically described region around a nucleus in an atom or molecule that may contain zero, one, or two electrons. Electrons arrange themselves in cloudlike regions around the nucleus called orbitals

The Atomic Number indicates how many protons an atom has and determines what type of atom it is. Strontium is the 38th element and its nucleus contains 38 protons.

Each proton weighs 1 AMU (Atomic Mass Unit) ≅ 1.67×10−27 kilograms

1 proton = 1836 electrons

The atomic weight is the average number of neutrons in all of the different versions or isotopes of that element.

Radioactive atoms have an unstable nuclei, which will eventually give off subatomic particles to become more stable, this releases energy or radiation. 

Elements often have radioactive and nonradioactive versions that change depending on the number of neutrons that atom has.

Different versions of elements are known as isotopes. For example, an isotope of Carbon is Carbon-14.

The number of protons and the number of neutrons determine an element’s mass number.

Mass Number = Protons + Neutrons

By subtracting atomic number from the mass number, we can calculate how many neutrons an atom has.