Model of the Atom 1. In 1911 Rutherford proposed the nuclear model of atomic structure. He suggested that an atom consists of a central nucleus (where most of the mass of the atom is concentrated) having a positive charge‚ surrounded by moving electrons carrying negative charge. Geiger and Marsden carried out an experiment to verify his proposal. The Geiger/Marsden a Particle Scattering Experiment 1. The apparatus is illustrated in the diagram below. | 2. The apparatus was in an evacuated
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CChemistry Exam #2 Study Guide (10/07/12) I. Bonding a. Ionic Bonding i. Electrons are transferred ii. Ions are held together by electrostatic force b. Covalent Bonding iii. Electrons are somehow shared iv. Electrons are attracted to nuclei (shared) II. Electronegativity c. The ability of an atom in a molecule to attract shared electrons to itself d. Measured on Pauling Scale e. Most electronegative: Fluorine. Then
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attractive force between the atoms ... a chemical bond. The two extreme cases of chemical bonds are: Covalent Bonds Covalent chemical bonds involve the sharing of a pair of valence electrons by two atoms‚ in contrast to the transfer of electrons in ionic bonds. Such bonds lead to stable molecules if they share electrons in such a way as to create a noble gas configuration for each atom. Hydrogen gas forms the simplest covalent bond in the diatomic hydrogen molecule. The halogens such as chlorine
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Nano- milli- 0.000‚000‚000‚001 0.000‚000‚001 0.001 centi- 0.01 deci- 0.1 deka- 10 hecto- 100 Kilo- 1‚000 Mega 1 kcal = 1000 cal 1 Cal= 1 kcal 1 cal = 4.184 1‚000‚000 • Neutral atoms contain the same number of electrons and protons. • Components of a mixture can be separated (purified) by physical means. • Physical changes alter a substance without any changes to the chemical composition. • Chemical change involves breaking down a substance into other substances
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Topic 5 – Bonding and Structure Revision Notes 1) Introduction • Atoms form bonds to get a full outer shell of electrons • There are three types of bonding: ionic‚ covalent and metallic • The structures produced by forming bonds are either giant or simple • The possible combinations of structure and bonding are giant ionic‚ simple covalent‚ giant covalent and giant metallic • Simple covalent is sometimes called simple molecular • Giant covalent is sometimes called giant
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involves the sharing of electron pairs between two atoms. Translation: -Ionic bonding happens between a metal and a non-metal (east coast and west coast) -One atom completely donates its valence electrons to another atom -Metals become CATIONS (positive charge/oxidation state); Non-metals become ANIONS (negative charge/oxidation state) Example: Na + Cl → Na+Cl- or Mg + O → Mg2+O2- -In covalent bonding one atom completely shares its valence electrons with another atom (west
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isomers can you draw for: C4H10O C4H8O 3. Chemical Bonds Ionic: forms by a complete transfer of one or more electrons from one atom to another to form ions (cation and anion). Forms between typical metal and non-metal due to a significant difference in electronegativity (ability of atom to attract electrons; refer to table 1.2). LiF Covalent: forms by sharing electrons between two atoms (polar covalent and non-polar covalent). Forms between non-metals. Electronegativity difference ∆ EN
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Introduction: According to the Bohr atomic model‚ electrons orbit the nucleus in fixed paths with specific energies. Each path is therefore often referred to as an “energy level”. Electrons possessing the lowest energy are found in the levels closest to the nucleus. Electrons of higher energy are located in progressively more distant energy levels. If an electron absorbs sufficient energy to bridge the “gap” between energy levels‚ the electron may jump to a higher level and become “excited”. Since
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simply put‚ the radius of an ion. An ion is a charged particle. Atoms become ions from the addition of electrons (giving them a negative charge) or the loss of electrons (giving them a positive charge). Ionic radius is defined as the distance between the nucleus of this charged particle (where the protons and neutrons reside) and the outermost edge of its electron cloud. Because the electron field surrounding an ion can vary‚ the ionic radius is generally measured by taking half the distance between
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combination of three nuclei and ten electrons possesses special properties that make it unique among the more than 15 million chemical species we presently know. When we stop to ponder the consequences of this‚ chemistry moves from being an arcane science to a voyage of wonder and pleasure as we learn to relate the microscopic world of the atom to the greater world in which we all live. The molecule of water A molecule is an aggregation of atomic nuclei and electrons that is sufficiently stable to possess
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