Hi, so today, we're going to talk about atomic structures and inner atomic bonding. And our first aspect is going to be looking at the periodic table, and what we want to do at the end of this lecture, be able to describe the elements atomic structure, in terms of atomic weight atomic number. And those entities that make it up, as well as, look at a little bit of the characteristics of the periodic table, and how it's organized. Okay, so we look at the atomic structure review, we have the basic units, electrons negative charge, protons positive charge, neutrons neutral. The electron, which is a near massless particle, you can see by its rest mass of 9.1 times 10 to -13 kg. And then, you have the larger units, the proton neutrons which come in at very large weight of 1.6, 7 times 10 to the -27 kg. When we talk about the atomic number, that's usually the some of the [COUGH] The atomic number, the number of protons in the nucleus. Generally, the number of electrons. So hence, we have a balance of positive and negative charge. The atomic weight is the actual some of the protons and neutrons, okay? The ones that are actually listed are going to be the average, okay? Because we can have isotopes and we can have a variant of the number of neutrons, the number of protons, excuse me, not the number of protons but the number of neutrons. In this case, we can have say carbon 12, we can also have carbon 13. Silicon 28, the most common but we do indeed have Silicon 29 and silicon 30, okay? And then, when we think about this weight, we often look at the weight of one mole. One mole is the number 6.022 times 10 to the 23 molecules or atoms per weight. Okay, I mean I should say per likelier weight or atomic weight. Okay, and one AMU, one atomic mass unit per atom is one gram per mole. Okay, alright, so case carbon would be 12 AMU per mole. Now, why are we interested in the periodic table? Often we say material science, we don't want to understand the nature and model phenomena. If we're engineering, we want to apply math and science to create new discoveries to address societal needs. Okay, so sometimes from a chemist standpoint, we as material scientists were interested in bonding chemical reactions, thermochemistries, solutions. Material science and engineers often interested in the bond strength, because the properties at the micro scale are also valid at the macro scale, okay? Sometimes, we're interested in electronic properties. How do we create or modify silicon metal, such that we can develop an integrated circuit? We'll be interested in solubility and diffusibilty. These things will allow us to process and modify the properties of the material. How did this all come out to be? The periodic table came from outcomes in modern physics and quantum mechanics. The Bohr model which was a aspect of modern physics, and then the Hund's rule or also Born Rule showed us how the actual structure of the atom took place and how the energy levels are quantized. So we're able to come up with electronic configuration of the atoms based on outcomes from modern physics and quantum mechanics. Okay, so here we're going to look at the electronic configuration of Iron. Okay, so we start off with the atomic number. Okay, and we're going to use the Hund's rule also Borns Law to show us how we're going to feel. Okay, so we're feeling the 1S. Okay, we're going to fill the 1S, okay ,so there are two electrons per energy level because one will have a spin up spin down, that's your quantum number S plus or minus S. Then, that means we just filled in the 1S, we gotta fill in the 2S. And they would keep right on Tltill finally we get we just filled in the 4S. Now, we're going to come to the 3D. We feel one, one, one, spin up spin down. Now, we're left with the paired electrons and they give ironist magnetic properties, okay? So now, we're left finally with the electronic configuration of Iron, and notice these outer electrons unfilled. These energy levels unfilled is referred to as a valence electrons. And that also says that this Iron can react since these guys are unfilled, and we'll see that later on. So let's take a moment for inquiry. Okay, so the question is match the electronic structure with the periodic table element that is represented by this configuration. Okay, so we're going to go, so we start off with the 1S is filled, they went down 2S, then 2P. Now, we're filling in the 3S, so that puts us here, and then we're going to go 5, one, two, three, four, five. That's chlorine, and that would be our halogen.
