Chemistry Revision F331 Isotopes - atoms with the same atomic number‚ but different mass numbers 131I - radioactive tracer for thyroid. 99Tc for tumours. Radioisotopes - gamma emitters & short half life - long enough to detect‚ but not long enough for damage. Beta particles emitters are more useful than alpha particle emitters because they penetrate more and so are more easily detected. Also‚ less damaging. The half life is the time taken for half the isotope to decay Mass left = initial
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What is a Functional Group? A functional group is a portion of a molecule that is a recognizable/classified group of bound atoms. In organic chemistry it is very common to see molecules comprised mainly of a carbon backbone with functional groups attached to the chain. The functional group gives the molecule its properties‚ regardless of what molecule contains it*; they are centers of chemical reactivity. The functional groups within a molecule need to be identified when naming. *Definition taken
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6753_Klein_00.qxd 5/1/07 5:02 PM Page ii 6753_Klein_00.qxd 5/1/07 5:02 PM Page i 6753_Klein_00.qxd 5/1/07 5:02 PM Page ii 6753_Klein_00.qxd 5/15/07 2:14 PM Page iii ORGANIC CHEMISTRY I AS A SECOND LANGUAGE Second Edition DR. DAVID R. KLEIN Johns Hopkins University JOHN WILEY & SONS‚ INC. 6753_Klein_00.qxd 5/1/07 Marketing Manager Production Manager Production Editor Cover Designer 5:02 PM Page iv Amanda Wygal Pamela
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“REDEFINITION OF THE KILOGRAM TABLE OF CONTENT Contents 1.0 LITERATURE REVIEW It is only the Kilogram in the International System (SI) that is defined by a monument: the International kilogram prototype (IPK). The feasible changes in International prototype Kilogram (IPK) may result in imbalances in international system (SI) unit as some other units in the SI depend on the kilogram for their definition and
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than the speed of sound. This produces a shock wave‚ a sonic boom. The colors are produced by heating metal salts‚ such as calcium chloride or sodium nitrate‚ that emit characteristic colors. The atoms of each element absorb energy and release it as light of specific colors. The energy absorbed by an atom rearranges its electrons from their lowest-energy state‚ called the ground state‚ up to a higher-energy state‚ called an excited state. The excess energy of the excited state is emitted as light
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HOMEWORK EXAM 3: Chapter 19: The half life of 90Sr is 29 years. What fraction of the atoms in a sample of 90Sr would remain 175 years later? Answer 0.166 0.125 0.062 here 0.015 Which relation is not correct? Answer 11p = 11H = proton 0-1e = 0-1β = electron here +10e = +10β= positron 10n = neutron As a result of beta decay‚ the product nucleus is Answer one atomic number lower than the original element. two atomic number
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cathode rays carry negative charge and identified the cathode rays inside vacuum tubes as being electric currents composed of these tiny electrons (Hamblin‚ 2005). It was the crucial first step in the development of the twentieth-century concept of the atom (Simmons‚ 1996). In the following paragraphs‚ I will introduce the Thomson’s life and his important achievements. Biographical information J.J. Thomson was born at Cheetham Hill‚ a suburb of Manchester‚ England on December 18‚ 1856. His father
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electrons atom behaviour is because of electrons hydrogen almost always loses its electron‚ leaving it a hydrogen ion taking away a negative charge creates a cation adding a negative charge creates an anion electronegativity is the ability to steal electrons electronegativity is influenced by the number of electrons needed to complete the valence shell nonpolar covalent bonds: electrons are shared equally polar bonds: electrons are shared unequally; pulled more toward one atom and have charge
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Presence of double bond make alkenes very reactive. There are many substances which react with alkenes by opening out the double bond to form two single bonds these are called addition reactions. An alkyl group is an alkane molecule with one hydrogen atom missing it does not exist on its own‚ but is part of another molecule. Alkyl groups are named by deleting the -ane from the
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perform a quantitative analysis of these substances" (Internet 1). 2.2 The electrons of an atom exist in different energy levels. When energy is added to an atom in the form of light/heat/electrical energy‚ the atom becomes excited and electrons begin to ’jump ’ to higher energies (Figure 1). There are two states that an atom can exist - an excited state and a ground (natural) state. The ground state of an atom is when the electrons are in their lowest energy level. The use of a flame photometer "relies
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