with the specific orientation of bonding atoms. A careful analysis of electron distributions in orbitals will usually result in correct molecular geometry determinations. In addition‚ the simple writing of Lewis diagrams can also provide important clues for the determination of molecular geometry. Click on a picture to link to a page with the GIF file and a short discussion of the molecule. Steric Number (# bonded atoms + # electron pairs) 6 5 4 3 2 AX6 octahedral AX5 trigonal bipyramidal
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They name for these beta rays was soon replaced by the name electron. The English physicist by the name of JJ Thomson‚ discovered the electron in 1897. He was certain that every atom consisted of electrons. He deduced that since an atom contains a neutral charge and consists of negative electrons‚ there must be some other positively charged material within the atom to balance out the negatively charged electrons. He realized that the electrons alone could not account for the mass of one atom due to
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ionic bonding Molecule (nonmetal +nonmetal): covalent bonding 3.1 Metallic Bonding 1) Definition The electrostatic attraction between a lattice if positive ions and delocalized electrons. 2) The strength of metallic bonding (depend on) Delocalized electrons (=valence electrons=Group number) More valence electrons‚ stronger metallic bonding Ionic radii (=distance between nucleus and e-) Greater ionic radius‚ farther distance between nucleus and Ve-‚ stronger the metallic bonding 3) Physical
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sparks (electrons being released) more rapidly. Since light was predominately now thought to just be a wave‚ three main objections were raised in regard to Hertz’s observation of this now-called photoelectric effect. In 1914‚ Robert Millikan noticed that there was a cutoff frequency‚ ‚ at which no more electrons are shot out of the conducting electrodes (this work won him the 1923 Nobel Prize). Other experiments at the time showed that the maximum kinetic energy of the fasted ejected electron‚ ‚ was
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together to become a stable‚ new substance called a compound. -the number of valence electrons determines if an atom will form a chemical bond. -metals tend to give up electrons to other atoms. -nonmetals tend to take electrons from other atoms. -noble gases will not form a chemical bond because these atoms already have a full outer shell of energy. Ionization: the process of gaining or losing electrons to become an ion. -ion: atom that has a net positive or negative charge. -anion (negative
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Electricity is a form of energy. Electricity is the flow of electrons. All matter is made up of atoms‚ and an atom has a center‚ called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton‚ and the number of electrons in an atom is usually equal to the number of protons. When
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physicist‚ J.J. Thomson‚ shortly after discovering electrons‚ proposed his Plum-Pudding model of the atom. He based this model on the two facts that he knew at the time: 1. atoms contain small negatively charged particles called electrons and 2. atoms behave as if they have no charge at all‚ meaning they are electrically neutral. Thomson assumed there must be something in an atom that was positively charged that would neutralize the electrons negative charge. His proposal was a model for the atom
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OF SOLIDS According to quantum free electron theory of metals‚ a electron in a metal experiences constant(or zero) potential and free to move inside the crystal but will not come out of the metal because an infinite potential exists at the surface. Bloch Theorem: According to this theorem‚ the periodic potentials due to the positive ions in metal have been considered. (i.e. the electrons moves in a periodic potential provided by lattice). If the electron moves through these ions‚ it experiences
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an atom. The photoelectric effect is inversely proportional to the kV cubed and is proportional to the atomic number cubed. The photon is completely absorbed. The ejected electron is known as the photoelectron. In Compton scatter the incident photon is both absorbed and scattered. The ejected electron is known as a recoil electron which is scattered in the forward direction. The photon has a longer wavelength than the incident photon due to loss of energy. Pair production never occurs in diagnostic radiography
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charged (non-charged) neutrons are found in the nucleus Negatively charged electrons are located orbiting the nucleus in shells. They stay in orbit because the electrons are attracted to the protons 2: The Element Introduction An element is a singular type of atom‚ like candy in a candy shop If there is an atom that has 8 protons and 8 electrons‚ then it is an oxygen element. If it has 1 proton and 1 electron‚ then it is a hydrogen element 3: Molecules Introduction A molecule
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