Born-Oppenheimer approximation. Along with nuclear dynamics problem‚ electronic structure problem is one of the two steps to study quantum mechanical motion of a molecular system. Except for a small number of simple problems such as hydrogen-like atoms‚ the solution of electronic structure problems require modern computers. Electronic structure problem is routinely solved with quantum chemistry computer programs. Electronic structure calculations rank among the most computationally intensive tasks
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charged atoms‚ which means that the number of electrons is never less than the number of protons. Non-metals become negatively charged atoms‚ and now the number of electrons is more than the number of protons. When atoms share electrons of nonmetals then a covalent bond is formed inside the molecule. Monatomic elements are elements that only contain one type of atom. An example of this would be the noble gases‚ such as Helium or Neon. Diatomic elements are molecules that contain two atoms. An example
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valence-shell electron-pair repulsion (VSEPR) theory. The VSEPR theory assumes that each atom in a molecule will achieve a geometry that minimizes the repulsion between electrons in the valence shell of that atom. The five compounds shown in the figure below can be used to demonstrate how the VSEPR theory can be applied to simple molecules. There are only two places in the valence shell of the central atom in BeF2 where electrons can be found. Repulsion between these pairs of electrons can be minimized
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Rutherford discovered the nucleus in 1911 -Atoms of different elements combine in whole number ratios to make compounds. -In chemical reactions‚ atoms are combined‚ separated o rearranged. -All matter is composed of extremely small particles called atoms. -Atoms may have different isotopes (basically a different number of neutrons in the nucleus) and hence have different mass. -Atoms cannot be created or destroyed in a chemical reaction. -Atoms can be split‚ as in the decay of Uranium
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questions and concepts so that you can build on the basics to understand the complex material These are just the basics of what is covered in class lectures. This should not be the only resources you use to study. Who developed the concept of atoms? What are atoms? What is the Law of conservation of mass? What is the law of definite proportions? What is Dalton’s Atomic Theory? Atomic Structure (Experimental Evidence for Atomic Structure): CH.2 [Section 1] 1. Circa 400-5 BCE (Greek Philosopher Democritus)
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BC The question: Can matter be divided into smaller particles? Or can it be infinitely divided? Matter can be divided into the smallest piece‚he named it “atomos”: not to be cut. Said that atoms were small‚ hard particles that were all made of the same material but were different shapes and sizes. Atoms were infinite in number‚ always moving and capable of joining together. His theory was ignored and forgotten for more than 2‚000 years becaus the eminent philosophers of the time‚ Aristotle and
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2 The Components of Matter Elements‚ Compounds‚ and Mixtures: An Atomic Overview An element consists of only one kind of atom. An element is one kind of substance – the composition is fixed. Each element is unique because the properties of its atoms are unique. Molecules are structures containing two or more atoms chemically bound together. Diatomic molecules are two-atom molecules such as elemental oxygen. A compound is a type of matter in which two or more different elements are chemically bonded
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Name: Cayla Klimach Date: 2/13/15 Student Exploration: Element Builder Vocabulary: atom‚ atomic number‚ electron‚ electron dot diagram‚ element‚ energy level‚ ion‚ isotope‚ mass number‚ neutron‚ nucleus‚ periodic table‚ proton‚ radioactive‚ valence electrons Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. What are some of the different substances that make up a pizza? :Cheese‚ tomato sauce‚ meat 2. What substances make up water? Hydrogen & Oxygen (H2O) 3. What substances
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CHEM 101 – General Chemistry I Chapter 2 Reading Assignment Pages 31 - 60 2.1 – What is Matter Made Of? Who 1st discovered atoms – Democritus where the first person to discover atoms. His followers would often think that there were multiple kinds of atoms and not just plain atoms. 2.2 – How Do We Classify Matter? Elements – A substance that consists of identical atoms. Today there are 116 known elements. Example – C= Carbon; H= Hydrogen Compounds – A pure substance made up of two or more elements
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Covalent Bonds Covalent bonds are formed when atoms share electrons‚ one from each atom in a single bond‚ to form electron pairs‚ usually making their outermost shells up to eight electrons by this means. This would make them more stable‚ less reactive and an electronic structure like a noble gas. They are most frequently formed between pairs of non-metallic elements. Non-metallic elements usually have from four to eight electrons in their outermost shells‚ the so-called valency electrons‚ which
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