The Periodic Table and Me

 

1. The purpose and history of the periodic table.

The purpose of the of the periodic table is to arrange chemical elements in an organised way based on their electron configurations, atomic numbers, and chemical properties. The periodic table has vertical rows called groups, and the lower you go, the more shells an atomic has (it gets bigger). The periodic table also has periods, which as horizontal rows of the periodic table. The development of the modern periodic table started with Dmitri Mendeleev, who in 1869, arranged the table by atomic mass, and similar properties. In 1914, Henry Moseley rearranged the periodic table to atomic numbers, which was based on the atomic weight, and from since their on, our periodic table was made. 

 

2. The arrangement of the periodic table.

The periodic table is arranged by atomic numbers. It is also arranged by their electron configurations (valences), and chemical properties, and periodic trends. These periodic trends include the atomic radii trend, the ionic radii trend, ionisation energy, electron affinity, electronegativity, and valence electrons. If you look on a at arrows and that describe the trend, you'll see a pattern, and that it's not just random. Periodic tables also have physical properties, chemical properties. 

 

3. Trends about which you have learned using the periodic table (explain at least 2 of them).

I've learned the atomic radii trend, the ionic radii trend, ionisation energy, electron affinity, electronegativity, and valence electrons. The ones I found the most interesting were the atomic radii trend and the ionisation energy. In atomic radii, the elements get bigger as you go down and left on the periodic table. This is because the further down the period, the more shells it has. For example, period 1 would only have 1 shell, whereas period 6 would have 6 shells, it's kinda common sense. However, as you move further to the left of the periodic table, the bigger it gets, despite having a smaller atomic number. Why? This is because of the protons, the more proton you have (atomic #) the more it will pull in the outer electrons, thus making the atom smaller. Ionisation energy gets bigger as you go to the top and right of the periodic table (exclude group 18). This is because the more right you go, the more valence electron an atom has. For example, group 17 elements only need 1 more electron, so it will fight and try to get that last electron to become stable. And as you go up the periodic table, the more energy it has, as the less shells an atom has. Because they're less shells, the closer the outer valence electron is to the nucleus, which attracts the outside. For example, fluorine, in group 17, only has 2 shells, and needs only one electron to make it stable. So the electron will definitely try to get one more.