81. Rafter Radiocarbon Laboratory: Measuring 14C Provided three or more electrons are removed from the molecular ions the moleculesdissociate into their component atoms at the stripping stage. http://www.rafterradiocarbon.co.nz/measure.htm

How is a radiocarbon age measured? To determine the radiocarbon age of an organic material it is necessary to measure the proportion of radiocarbon ( C) in the carbon that it contains. There are currently two methods in use for doing this: Radiometric counting, in which the rate of radioactive decay of the C in the material is measured; Accelerator Mass Spectrometry, in which a particle accelerator is used to directly count the relative numbers of the atoms of the different carbon isotopes present in the material. Once the C content is known, it is compared to that of a standard material. The difference between the sample material and the standard is attributed to the time that has elapsed since the sample was "alive". For example, the radiocarbon age of a piece of wood gives the time since the wood was growing. How does radiometric counting work? Radiometric counting determines the amount of C present in a sample by measuring its radioactivity. This is done by converting the carbon in the material being dated to a gas such as CO or methane, or to benzene, and placing it in a suitable radiation detector. There are two types of counting systems in use:

82. MSN Encarta - Related Items - Atom Chemical Reaction, redistribution of atoms among molecules Chemical Reaction,process by which atoms or groups of atoms are redistributed, resulting in http://encarta.msn.com/related_761567432/Atom.html

var fSendSelectEvents = true; var fSendExpandCollapseEvents = true; var fCallDisplayUAText = false; MSN Home My MSN Hotmail Shopping ... Sign In Web Search: Encarta Subscriber Sign In Help Home ... Upgrade your Encarta Experience Search Encarta Related Items from Encarta Atom Chemical Reaction, redistribution of atoms among molecules Chemistry: Atoms and Molecules Elementary Particles Molecule, combination of two or more atoms ... , process by which atoms or groups of atoms are redistributed, resulting in a change in the molecular composition of substances. An... View article © 2005 Microsoft MSN Privacy Legal Advertise Feedback ... Help

83. Chemical Sciences Electrons Shared Covalent Bonding For example, in the molecule of water (H2O), each hydrogen atom found incomplex ions or molecules in which the central atom is a transition metal ion. http://www.psigate.ac.uk/newsite/reference/plambeck/chem1/p01241.htm

84. Ion - Wikipedia, The Free Encyclopedia The recombining of ions and electrons to form neutral atoms is called an electron in its lowest energy state from an atom or molecule of a gas with less http://en.wikipedia.org/wiki/Ion

Ion From Wikipedia, the free encyclopedia. This article is about the electrically charged particle. For other uses of this word, see ion (disambiguation) An ion is an atom or group of atoms with a net electric charge. A negatively charged ion, which has more electrons in its electron shell than it has protons in its nucleus , is known as an anion , for it is attracted to anodes , and a positively charged ion, which has fewer electrons than protons, is known as a cation (pronounced cat eye on ), for it is attracted to cathodes . The process of converting into ions and the state of being ionized is called ionization . The recombining of ions and electrons to form neutral atoms is called recombination Polyatomic anions which contain oxygen are sometimes known as oxyanion Atomic and polyatomic ions are denoted by a superscript with the sign of the net electric charge and the number of electrons lost or gained, if more than one. For example: H S O Contents Ionization potential Other ions History Etymology ... edit Ionization potential Main article: Ionization potential The energy required to detach an electron in its lowest energy state from an atom or molecule of a gas with less net electric charge is called the ionization potential , or ionization energy . The n th ionization energy of an atom is the energy required to detach its n th electron after the first n - 1 electrons have already been detached.

85. Physical Science | Session 4 However, if during a collision, an atom or ion of one molecule feels a force of the atoms/ions in a second molecule that is stronger than the force that http://www.learner.org/channel/courses/essential/physicalsci/session4/closer2.ht

Jump to Session 1. What is Matter? 2. The Particle Nature of Matter 3. Physical Changes... 4. Chemical Changes... 5. Density and Pressure 6. Rising and Sinking 7. Heat and Temperature 8. Extending the Particle Model Session 4 Intro A Closer Look Children's Ideas Featured Class ... Where Does the "Weight" Go? A Closer Look: The Chemical Reactions Shown in the Session 4 Video How does this apply to the two different reactions that appear in the video? 1. Lye (drain cleaner) and Epsom salt We begin by dissolving the compound Epsom salts in water, thereby splitting the molecule into its component atoms and ions. The second compound, the lye (or liquid drain cleaner) is already dissolved in water. When these two reactants are mixed together, the ions that make up the sodium hydroxide and magnesium sulfate collide. Because the forces attracting these particles to each other are greater than the forces between them and the water molecules, new molecules of magnesium hydroxide and sodium sulfate are formed. We see white products "precipitate" out of the clear mixture and the solution that remains is different from either of the original reactants: 2. Baking soda and Vinegar

86. Co-ordinate (dative Covalent) Bonding A covalent bond is formed by two atoms sharing a pair of electrons. Six watermolecules bond to the aluminium to give an ion with the formula Al(H2O)63+ http://www.chemguide.co.uk/atoms/bonding/dative.html

CO-ORDINATE (DATIVE COVALENT) BONDING This page explains what co-ordinate (also called dative covalent) bonding is. You need to have a reasonable understanding of simple covalent bonding before you start. Important! If you are uncertain about covalent bonding follow this link before you go on with this page. Co-ordinate (dative covalent) bonding A covalent bond is formed by two atoms sharing a pair of electrons. The atoms are held together because the electron pair is attracted by both of the nuclei. In the formation of a simple covalent bond, each atom supplies one electron to the bond - but that doesn't have to be the case. A co-ordinate bond (also called a dative covalent bond) is a covalent bond (a shared pair of electrons) in which both electrons come from the same atom. For the rest of this page, we shall use the term co-ordinate bond - but if you prefer to call it a dative covalent bond, that's not a problem! The reaction between ammonia and hydrogen chloride If these colourless gases are allowed to mix, a thick white smoke of solid ammonium chloride is formed. Ammonium ions, NH

87. Definitions Ion An atom or molecule that has a negative or positive charge as a result Oxidation An atom, an ion, or a molecule is said to undergo oxidation or to http://www.eserc.stonybrook.edu/ProjectJava/ChemicalChargeApplet/definitions.htm

Definitions Anion A negatively charged ion, formed by addition of electrons to atoms or molecules (Reduction). Group Number Number of Electrons Gained Charge of Anion Formed IV V VI VII VIII no tendency to form anions Cation A positively charges ion, formed by removal of electrons from atoms or molecules (Oxidation). Group Number Number of Electrons Lost Charge of Cation Formed I II III IV Compound A chemical combination of atoms of different elements to form a substance in which the ration of combining atoms remains fixed and is specific to that substance. The constituent atoms cannot be separated by physical means; a chemical reaction is required for the compounds to be formed or to be changed. The existence of a compound does not necessarily imply that it is stable. Many compounds have lifetimes less than a second. Electron An elementary particle of negative charge (- 1.602 x 10-19 C), and rest mass (9.109 x 10-31 kg). Electrons are present in all atoms in shells around the nucleus. Empirical Formula The formula of a compound showing the simplest ratio of the atoms present. The empirical formula is the formula obtained by experimental analysis of a compound and it can be related to a molecular formula only if the molecular weight is known. For example, P

88. Springer Handbook Of Atomic, Molecular, And Optical Ph...-Springer Atoms, Molecu ElectronAtom, Electron-Ion, and Electron-Molecule Collisions Electron – Atomand Electron – Molecule Collisions Chap. 64. Ion – Atom Scattering http://www.springeronline.com/sgw/cda/frontpage/0,11855,5-10102-22-45788381-deta

Please enable Javascript in your browser to browse this website. Select your subdiscipline Atoms, Molecules, Clusters Biophysics Condensed Matter Geophysics Mathematical Physics Quantum Physics Home Atoms, Molecules, Clusters Select a discipline Biomedical Sciences Chemistry Computer Science Economics Education Engineering Environmental Sciences Geography Geosciences Humanities Law Life Sciences Linguistics Materials Mathematics Medicine Philosophy Popular Science Psychology Public Health Social Sciences Statistics preloadImage('/sgw/cda/pageitems/designobject/cda_displaydesignobject/0,11978,5-0-17-900180-0,00.gif'); preloadImage('/sgw/cda/pageitems/designobject/cda_displaydesignobject/0,11978,5-0-17-900170-0,00.gif'); preloadImage('/sgw/cda/pageitems/designobject/cda_displaydesignobject/0,11978,5-0-17-900190-0,00.gif'); preloadImage('/sgw/cda/pageitems/designobject/cda_displaydesignobject/0,11978,5-0-17-900200-0,00.gif'); preloadImage('/sgw/cda/pageitems/designobject/cda_displaydesignobject/0,11978,5-0-17-900369-0,00.gif'); preloadImage('/sgw/cda/pageitems/designobject/cda_displaydesignobject/0,11978,5-0-17-900344-0,00.gif');

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

Page 5     81-88 of 88    Back | 1  | 2  | 3  | 4  | 5