what an atom is and what its components are. One of these discoverers‚ John Dalton‚ developed the first modern atomic theory. Although much of his theory is still true today‚ one point was disproved by Ernest Rutherford. Dalton’s atomic theory had several parts to it. He believed atoms were indivisible‚ or impossible to break down into smaller particles. Also‚ he said elements are all consisted of atoms and that the atoms of each element are different from each other. All of the atoms of the
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Combining a pair of helium atoms with 1s2 electron configurations would produce a molecule with a pair of electrons in both the bonding and the * antibonding molecular orbitals. The total energy of an He2 molecule would be essentially the same as the energy of a pair of isolated helium atoms‚ and there would be nothing to hold the helium atoms together to form a molecule. The fact that an He2 molecule is neither more nor less stable than a pair of isolated helium atoms illustrates an important principle:
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Chapter 2 The Chemical Context of Life PowerPoint Lectures for Biology‚ Seventh Edition Neil Campbell and Jane Reece Copyright © 2005 Pearson Education‚ Inc. publishing as Benjamin Cummings • Overview: Chemical Foundations of Biology Copyright © 2005 Pearson Education‚ Inc. publishing as Benjamin Cummings • The bombardier beetle uses chemistry to defend itself Figure 2.1 Copyright © 2005 Pearson Education‚ Inc. publishing as Benjamin Cummings • Concept 2.1: Matter consists
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Writing Lewis Dot Formula November 8‚ 2013 I. Learning Objectives At the end of the sessions‚ the students of III- 15‚ and III – 10 must be able to: 1. Students will be able to interpret and draw Lewis dot diagrams for individual atoms and both covalent and ionic compounds. II. Subject Matter A. Topic: Chemical Bonding B. References 1. Department of Education‚ Culture and Sports. (1991). Science and Technology III. Quezon City: Book Media Press‚ pp. 273. 2. Estrella‚ Mendoza E. Chemistry
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Electrons" Theory 14 Conductors‚ Insulators and Semiconductors 16 25 IONIC BOND Ionic bond is formed when electron transferred from a valence shell of an atom to the valence shell of another atom. Ionic bond involves electron transfer across two atoms. The atom which donates the electron is called cation which is a positive ion whereas the atom which gains the electron is called anion which is a negative ion. The opposite charge of cation and anion attract one another due to the electrostatic force
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Democritus was an Ancient Greek pre-Socratic philosopher of Ancient Greece. He along with Leucippus were atomic theorists who proposed during the fifth century B.C that 1. Matter is composed of atoms separated by empty space by which atoms move. 2.Atoms are solid‚ homogeneous‚ indivisible‚ and unchanging. Democritus knew that if he took a rock and chisel it in half‚ that both halves would characteristically have the same properties as the whole. He rationalized that if he was to continue to cut the
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required by an organism in minute quantities ATOM- smallest unit of matter that still retains the properties of an element NEUTRONS- no electrical charge ELECTRONS- negative charge PROTONS- positive charge ATOMIC NUCLEUS- formed by neutrons and protons ATOMIC NUMBER- number of protons in its nucleus MASS NUMBER- the sum of protons and neutrons in the nucleus ATOMIC MASS- the atom’s total mass‚ can be approximated by the mass number ISOTOPES- two atoms of an element that differ in the number of
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chWho is he? * British chemist and physicist * Born 1887 * Scientific background * Eton * Trinity College Contribution and achievements * Discovered wavelength (energy) of an X-ray depended on the nuclear charge of an atom * Moseley observed and measured the X-ray spectra of various chemical elements obtained by diffraction in crystals. * The Moseley’s law. * Periodic Table. * Early X-ray crystallography * development of early X-ray spectrometry equipment
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distinct shapes are called ‘crystalline solids’. Crystalline solids are further divided into five groups: atomic‚ molecular‚ network‚ ionic‚ and metallic. The type of bonding in a substance depends on the type of atoms it contains and the forces of attraction that exist between the atoms. Some of these properties are hardness‚ solubility‚ electrical conductivity‚ and melting point. Ionic solids are those that have forces of attraction between oppositely charged ions. Ionic bonds allow the substance
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does Dalton’s atomic theory account for the fact that when 1.000 g of water is decomposed into its elements‚ 0.111 g of hydrogen and 0.889 g of oxygen are obtained regardless of the source of the water? *Using Dalton’s theory‚ it is said that he atoms of elements combine in constant ratios to form compounds. Regardless of the water source‚ when the water was decomposed to its elements‚ there is really a constant ratio between the two elements composing the water. 6. Summarize the evidence
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