Quantum Theory Periodic Trends: Fill & Download for Free

Greg Burns explained the pattern of the periodic trends in the filling of electronic orbitals.Now getting to the Why?, well the answer is that we don’t know.The periodic trends in the shape and number of orbitals of atoms as their atomic number rises are described by Quantum Mechanics. It is useful at this point to remember that Quantum Mechanics is a mathematical description of physical processes whose entire framework is based on six postulates. That’s right postulates, the theory just happens to fit the experimental measurements so Hallelujah! we keep it, it doesn’t explain anything though.Quantum numbers appear when you solve analytically the Schrödinger equation in the case of the single hydrogen atom and the Pauli principle is a direct consequence of one of the postulates.Cheers!

Yes. Just as Mendeleev was able to predict the properties of undiscovered elements in the periodic table when he created it, the trends in the Periodic Table are able to be used to predict properties of heavier elements.I should constrain my answer by specifying chemical and some physical properties, the ones that depend on electron configuration and so on.The periodic table has as its basis quantum theory, and thus the configuration of the electrons. This is so even though nothing of this was known when the Periodic Table was created.To predict the properties of the nucleus, other theory is used.However, we would not be able to create enough of these elements to hang around for long enough to be able to test the chemical properties.

Melting Point TrendsThe melting points is the amount of energy required to break a bond(s) to change the solid phase of a substance to a liquid. Generally, the stronger the bond between the atoms of an element, the more energy required to break that bond. Because temperature is directly proportional to energy, a high bond dissociation energy correlates to a high temperature. Melting points are varied and do not generally form a distinguishable trend across the periodic table. However, certain conclusions can be drawn from the graph below.Metals generally possess a high melting point.Most non-metals possess low melting points.The non-metal carbon possesses the highest boiling point of all the elements. The semi-metal boron also possesses a high melting point.Figure 7. Chart of Melting Points of Various ElementsMetallic Character TrendsThe metallic character of an element can be defined as how readily an atom can lose an electron. From right to left across a period, metallic character increases because the attraction between valence electron and the nucleus is weaker, enabling an easier loss of electrons. Metallic character increases as you move down a group because the atomic size is increasing. When the atomic size increases, the outer shells are farther away. The principle quantum number increases and average electron density moves farther from nucleus. The electrons of the valence shell have less attraction to the nucleus and, as a result, can lose electrons more readily. This causes an increase in metallic character.NoteMetallic characteristics decrease from left to right across a period. This is caused by the decrease in radius (caused by Zeff, as stated above) of the atom that allows the outer electrons to ionize more readily.Metallic characteristics increase down a group. Electron shielding causes the atomic radius to increase thus the outer electrons ionizes more readily than electrons in smaller atoms.Metallic character relates to the ability to lose electrons, and nonmetallic character relates to the ability to gain electrons.Another easier way to remember the trend of metallic character is that moving left and down toward the bottom-left corner of the periodic table, metallic character increases toward Groups 1 and 2, or the alkali and alkaline earth metal groups. Likewise, moving up and to the right to the upper-right corner of the periodic table, metallic character decreases because you are passing by to the right side of the staircase, which indicate the nonmetals. These include the Group 8, the noble gases, and other common gases such as oxygen and nitrogen.In other words:Move left across period and down the group: increase metallic character (heading towards alkali and alkaline metals)Move right across period and up the group: decrease metallic character (heading towards nonmetals like noble gases)Figure 8. Periodic Table of Metallic Character TrendOutside LinksPinto, Gabriel. "Using Balls of Different Sports To Model the Variation of Atomic Sizes." J. Chem. Educ.1998 75 725.{cke_protected}{C}Qureshi, Pushkin M.; Kamoonpuri, S. Iqbal M. "Ion solvation: The ionic radii problem." J. Chem. Educ.1991, 68, 109.Smith, Derek W. "Atomization enthalpies of metallic elemental substances using the semi-quantitative theory of ionic solids: A simple model for rationalizing periodic trends." J. Chem. Educ. 1993, 70, 368.Ionization Energy Trend:Other Periodic Table Trends:Dr. Enderle's (UCD) Lecture on Periodic Trends (2 parts):(Part 1)(Part 2)ProblemsThe following series of problems reviews general understanding of the aforementioned material.1.) Based on the periodic trends for ionization energy, which element has the highest ionization energy?A