State the three subatomic particles in an atom and briefly explain them

The three sub-atomic particles are the following: protons, electrons and neutrons.

Explanation: Protons are positively charged particles and are found in the nucleus of an atom. This positively charged particles were associated to Ernest Rutherford with regards to its discovery. Along with the protons in the nucleus there were also neutrons that are neutral in charge. The third subatomic particles were the electrons. They were negatively charged particles and are found in the electron cloud region outside the nucleus. There are specific number of Electrons arrange in each orbitals, since they are prone to be moved in cases of chemical reactions. It was discovered by JJ Thompson using cathode rays and coined its name. For an atom to be electrically neutral or stable the number of electrons and protons must be equal.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.