GRAAD 12 NATIONAL SENIOR CERTIFICATE GRADE 11 PHYSICAL SCIENCES: CHEMISTRY (P2) EXEMPLAR 2013 MARKS: 150 TIME: 3 hours This question paper consists of 13 pages‚ 1 data sheet and a periodic table. Copyright reserved Please turn over Physical Sciences/P2 2 NSC – Grade 11 Exemplar DBE/2013 INSTRUCTIONS AND INFORMATION 1. Write your name in the appropriate space on the ANSWER BOOK. 2. This question paper consists of TWELVE questions. Answer ALL the questions in the ANSWER BOOK. 3. You
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1. Who are the authors? (Where are they doing their research? What kinds of research are they known for? What other things have they done?) Adam Hadhazy is a freelance science writer based in New Jersey. He is known for his research and reports on astronomy‚ biology and psychology; he has written other works such as‚ “Where Does the Period Table End?” which was published in discover magazine and‚ “The Reality of ‘Silicon Valley’” which was published in popular science. (Hadhazy) 2. What is the main
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in matter and energy and convert For example a plant uses carbon‚ sun‚ water from molecules of plant and nectar…humming bird takes sugar for energy Irritability Living things respond to changes in environment When dead no stability Homeostasis- physiological stability (not maintain results in fever) If Duggins adjusted thermostat we would all leave Regulation(homeostasis) Evolutionary Adaption Natural selection ( sea horse looks like coral to protect from predators) Hierarchy of Bio
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9.2.5 Chemistry past paper questions 2001 Question 16 (3 marks) Radioisotopes are used in industry‚ medicine and chemical analysis. For ONE of these fields‚ relate the use of a named radioisotope to its properties. Medicine – Iodine Ingested iodine concentrates in the thyroid gland and so iodine 131 can treat thyroid disorders (e.g. tumours) Iodine 131 has a half life of just over 8 days‚ emits beta particles and gamma rays as it decays. This half life is long enough for it to be transported form
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electrons that are shared between atoms‚ whereas non-covalent bonding involves the attraction of electromagnetic forces between atoms. Covalent bonds are strong and non-covalent bonds are weak. Both covalent and non-covalent bonds relate in a sense of stability as covalent bonds are most stable when its outmost electron shell filled‚ typically octet (or eight electrons)‚ and non-covalent bonds are stable when they have a strong electronegativity between two atoms. There are two types of covalent
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w w w e tr .X m eP e ap UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Ordinary Level .c rs om 5070/11 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Soft clean eraser Soft pencil (type B or HB recommended) October/November 2011 1 hour *0909424295* READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples‚ paper clips‚ highlighters‚ glue or correction fluid. Write your name‚ Centre number and
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the universe seeks stability‚ so do atoms. Each of these 4 atoms seeks stability through their electrons. For example‚ hydrogen has 1 electron in its valance shell and it has the ability to fill that shell with up to 2 electrons thus it seeks another atom that also has 1 electron in its valance shell to create stability. Another prime example is carbon‚ which has 4 electrons in its valance shell. It then seeks an atom with 4 electrons in its valance shell to create stability. These 4 elements
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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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solids Positive and Negative ions Strong electrostatic forces of attraction LiF‚ KCl‚ KNO3‚ BaSO4 2 Molecular solids Molecules Van der Waal’s forces. Dipole interactions. Hydrogen bonding I2‚ CO2 (solid)‚ HCl‚ Ice 3 Covalent solids Atoms Covalent bonds Diamond‚ Silicon 4 Metallic solids Positive metal ions (Kernels) and mobile electrons Metallic bonds All metals and some alloys Space Lattice and Unit Cell The constituent particles of a crystalline solid
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electron pair to BF3 to form a new bond. pKa’s AND ACID STRENGTH pKa - An alternative to Ka to describe acid strength. (A concise way to state the strength of an acid.) electron pair is not removed from the Lewis base. Instead‚ it is donated to an atom of the Lewis acid and one new covalent bond is formed. 5 1 Acid Strength and pKa • Acid strength is the tendency of an acid to donate a proton. • The more readily a compound donates a proton‚ the stronger an acid it is. • Acidity is measured by
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