The neutral state of atoms exists because the charges of protons and electrons cancel each other out. Each element fits neatly into its niche in the Periodic Table. Types of an element in which every atom has the same number of protons and the same number of neutrons are called isotopes. Any carbon 14 that was made at the time the earth was formed is now almost all gone.
Today’s atom is a spherical existence formulated from a positively charged nucleus consisting of protons/neutrons surrounded by one or more negatively charged electrons. Atoms with the same number of protons but different neutrons are called isotopes. Ions are atoms of the same number of protons but different number of electrons.
These electrons orbit the nucleus and make up the greatest portion of the atom’s volume. Isotopes cause an element’s atomic mass to be different than its mass number because the atomic number is the average of the isotopes masses whereas the atomic number is the sum of protons and neutrons. In the calculation of an atom’s charge, protons are 1, electrons are -1 and neutrons are neutral. ( 6) (-7)= -1 The integer that you find in each box of the Periodic Chart is the atomic number.
These developments led to the modern day structure of the atom. The atomic mass unit (amu) is based upon the standard of a carbon-12 atom, and states that 1/12 of a carbon-12 atom is one amu.
Namely, a nucleus containing protons/neutrons representing the bulk of the atoms mass with electrons orbiting around the center is the modern day representation of the atom. Carbon: C All atoms of the same element have the same number of protons but can have different numbers of neutrons, leading to different atomic masses. With atomic mass and isotopes affecting the mass of the atom, the next portion deals with the charge of the atom.
The rebounding nature of these few alpha atoms implied that perhaps the negatively charged portions were not part of the nucleus itself and that the center contained a positive portion with substantial mass.
Electrons, being so very small, could not have reflected the bulky alpha particles thus there must a large portion in the center having substantial mass with electrons revolving around this center.
The notion of matter and electric charge were understood but the actual components of the current were an anathema.
First among many experiments are the Cathode Ray Tube Experiments.
It was like shooting a rifle into a thin line of trees.
Some of the particles bounced off, some stuck inside, but the major portion of them passed through the gold foil.
Enter Ernest Rutherford, and his Gold Foil Experiments.