Notes

SUMMARY OF UNIT TEST
I. Development of the PT
1. Johann Dobereiner - made the triads, wherein the average of the atomic masses of the 1st and 3rd elements is (almost) equal to the atomic mass of the 2nd element.
2. John Newlands - made the "Octaves Law", wherein every 1st and 8th element out of 56 elements arranged according to increasing atomic weight had similarities in their physical and chemical properties.
3. Dmitri Mendeleev - known as the "Father of the Periodic Table", he was the one who introduced a periodic table of elements similar to the one we use today. He arranged the elements according to their atomic mass (and found apparent periodicity of properties) and predicted the existence of the elements which were not yet discovered during his time & left spaces for them in his table.
4. Julius Lothar Meyer - also created his own periodic table which included 28 elements arranged according to their atomic volume. If I'm not mistaken, he also took into account the periodic trends.
5. Henry Moseley - found a relationship between the X-ray wavelength and the atomic number of an element. His discovery led to the rearrangement of the periodic table according to the elements' atomic numbers instead of their atomic masses. His discovery also changed the way chemists think about the periodic table despite not making a periodic table himself.
6. (Not a chemist) Some elements are named after people (such as Einsteinium, which was named after Albert Einstein) and places (such as Dubnium, which was named after the town "Dubna" in Russia).
II. Modern PT
1. The periods of a periodic table are its rows, and the groups of a periodic table are its columns.
2. To find the group number of an element, look at the subscripts of its valence electrons (aka the electrons with the highest coefficient/s). And to find the period number of an element, look at the coefficient of its LSC. Finding the LSC is easy but to find the block number, look at the letter of the LSC.
3. Subshells d and f are "special".