intermolecular forces. 1+1 1 1 (ii) There are mobile electrons in solid sodium but the ions in solid sodium chloride are not free to move/ solid sodium chloride has no mobile ion. 1 1 (iii) Tetrachloromethane which is a covalent compound‚ does not possess any mobile electrons (ions)/ exists as (discrete) molecules in liquid state‚ therefore is not an electrical conductor 1 1993 - 4(a) Marking Scheme (i) Group II/ 2 Because W has 2 electrons in its outer/ outermost shell/ W is magnesium (Mg) 1
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Physics Folio Radioactivity Prepared By : Aniq Danial Bin Saharudin 5 Al – Hasseb Sekolah Menengah Sains Banting Contents No | Contents | Page | 1. | Appreciation | | 2. | Introduction | | 3. | Analysis : - Nucleus Of An Atom - Radioactive Decay - The Uses Of Radioisotopes - Nuclear Energy - The Importance Of Proper Management Radioactive
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he is credited with the discovery and identification of the electron; and‚ in a broader sense‚ with the discovery of the first subatomic particle. Thomson is also credited with finding the first evidence for isotopes of a stable (non-radioactive) element in 1913‚ as part of his exploration into the composition of canal rays (positive ions). He invented the mass spectrometer. J.J. Thomson discovered the electron. He found that the electron was a very small‚ negatively charged particles that are part
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Electrical Current An electric current is a flow of electrical charge. When a metal conducts electricity‚ the charge is carried by electrons moving through the metal. Electrons are subatomic particles with a negative electrical charge. When a solution conducts electricity‚ the charge is carried by ions moving through the solution. Ions are atoms or small groups of atoms that have an electrical charge. Some ions have a negative charge and some have a positive charge. Citric Acid Citric acid is
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uncharged object until they touch‚ and then they will repel one another. When charged objects attract uncharged objects‚ such as when the negatively charged plastic comb or fur attracted the paper‚ the negatively charged comb/fur repelled some of the electrons in the paper. This results in a redistribution of charges in the paper so that one side is more negative than the other side. The net effect is that the paper is attracted to the comb/fur. This also applies to the balloon attracting an uncharged
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a solid sphere‚ but what actually happened was that most of the atoms went through the gold foil.This showed that the atom wasn’t just a solid sphere like they believed but actually had a nucleus with electrons surrounding it. In 1897‚ a British physicist named J. J. Thomson discovered electrons through his cathode ray experiment. Thomson made the cathode ray by firing electrical currents through glass pipes filled with low-density gas. Thomson measured the ratio as always the same‚ regardless
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2.2 2.3 Shapes of molecules and ions 2.3a Electron pair repulsion theory a demonstrate an understanding of the use of electron-pair repulsion theory to interpret and predict the shapes of simple molecules and ions In a chemical species like a molecule or ion‚ pairs of electrons create negative centres that surround the central atom. These electron pairs repel each other and arrange themselves to be as far apart as possible‚ thus minimising repulsion. [pic](source: http://www.mikeblaber.org/oldwine/chm1045/notes/Geometry/VSEPR/Geom02
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1.) VSEPR theory is a model that is used in chemistry which helps to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. The molecule methane (CH4)‚ has a tetrahedral shape as it has 4 electron clouds‚ all of which are localized. This molecule is nonpolar because all the outer atoms are the same and are distributed symmetrically‚ the dipoles can cancel out even if polar bonds are present. 2.) The molecule of PCl3 is a polar molecule because
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attraction of electrons of a molecule by the positive nuclei in another molecule -the strength of the force is dependent on the number of electrons in the molecule (table 1 p. 259) Hydrogen Bonding -seen in compounds where a hydrogen if bonded to highly electronegative atoms with lone pairs of electrons such as: N‚ O and F. The boiling points are much higher than other hydrogen compounds of group V‚ VI and VII elements. -the proton (H) is being shared between two pairs of electrons (similar
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filaments and jets. Filaments and jets in the fourth state of matter contradict physics many hundred times but they clearly obey all laws of physics in the fifth state of matter. Spark‚ lightning‚ ion beam‚ mercury-filament (in mercury-lamps) and electron beam in TV have a characteristic cylinder-form with exact circular cross section‚ a well defined matter and a measurable
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