3a.  Democritus thought of the world being composed of very "uncuttable" particles.
3b.  Aristotle thought the earth was composed of matter, that he believed was made up of 4 elements.
4a. Dalton thought of all matter being composed of small particles, atoms.
4b. The subatomic particles are protons, neutrons, and electrons.
4c. Their number and arrangement makes them different.
5a. Electrons weigh 0 atomic mass units, protons weigh 1 atomic mass unit (1.67x10   g) , and neutrons weigh 1 atomic mass unit. Their weight makes them different sizes.
5b. Periodicity is the tendency to recur at regular intervals.
5c. An atom is a small component of a particle consisting of a nucleus containing combinations of neutrons, protons, and electrons.
5d. An ion is an atom in which the number of protons differs from the number of electrons.
5e. An anion is an atom that has more electrons than protons.
5f. A cation is if an atom has fewer electrons than protons.
5g. An isotope is an atom in which the number of protons and neutrons differ.
7a. The horizontal rows are called periods.
7b. The 3rd period contains 3 energy levels.
7c. The vertical columns are called groups.
7d. The atomic number represents the number of neutrons in the nucleus.
7e. The symbol for sodium is Na
7f. The mass of proton and mass of a neutron to get the atomic mass number.
7g. :
1.Uuq 2. Ng 3.Sn 4.Gd 5.Cf 6.Sr 7.No 8.Ba 9.Ta 10.Al
8a. An isotope is one particular form of an atom element might take.
8b. It has 6 protons and 6 neutrons, the "skinny" carbon is known as Carbon 12.
8c. The "medium" Carbon, is known as Carbon 13, it has 6 protons and seven neutrons.