The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. Atoms lack a well-defined outer boundary‚ so their dimensions are usually described in terms of an atomic radius. This is a measure of the distance out to which the electron cloud extends from the nucleus. However‚ this assumes the atom to exhibit a spherical shape‚ which is only obeyed for atoms in vacuum or free space. Atomic radii may be derived from the distances
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THE CHEMISTRY OF ORGANIC MOLECULES I. MACROMOLECULES-large molecules that are composed of smaller molecules and atoms that are bonded together. These are among the largest of all chemical molecules. A. Polymers-the largest of the macromolecules. These are composed of numerous‚ small identical subunits known as Monomers. There are 4 major polymers that are important for living organisms. These polymers are; carbohydrates‚ lipids‚ proteins and nucleic acids. B. Polymers
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come across a laboratory‚ classroom‚ chemistry textbook or lecture theatre that doesn’t contain a periodic table of the elements. It required the immense research and determination of the scientist Dmitri Mendeleev to show us that all elements followed a natural form and provided us with the first decent periodic table. There are 111 elements recognised today by IUPAC and they are arranged in the periodic table in horizontal groups and vertical periods. The eight groups consist of the alkali metals
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Periodic Classification of Elements Classification of Elements according to electron configuration ( type of subshell being filled) *valence electrons –outer electrons of atom which are those involved in chemical bonding ; accounts for similarities in chemical behavior among elemens within each of this groups * Representative elements/ Main Group elements * Group 1A-7A * Incompletely filled s/ p subshells * Display a wide range of physical and chemical properties
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Periodic Table of the Elements I 1. 1 1 2 H H He II 1.00794 3 2. 4. 5. 6. Li Be 9.012182 IV V VI 1.00794 4.002602 5 6 7 8 9 10 N O F Ne B C 10.811 12.0107 13 14 15 Si P 12 Na Mg Al 22.989770 24.3050 26.981538 14.00674 15.9994 18.9984032 20.1797 16 28.0855 30.973761 17 18 S Cl Ar 32.066 35.4527 39.948 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Br Kr 39.0983
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Chapter 1: Measurements (20) 1) The measurement 0.000 004 3 m‚ expressed correctly using scientific notation‚ is A) 4.3 x 10-7 m. B) 4.3 x 10-6 m. C) 4.3 x 106 m. D) 0.43 x 10-5 m. E) 4.3 m. Answer: B 2) Which of the following measurements has three significant figures? A) 0.005 m B) 510 m C) 0.510 m D) 0.051 m E) 5100 m Answer: C 3) Which of the following numbers contains the
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Periodic Table The periodic table is a table‚ where all known chemical elements are arranged. They are organized on the basis of their atomic numbers‚ electrons and chemical properties. The atomic of an element is the same as the number of electrons or protons in that particular atom. They elements in the table are placed in order from the lowest to the highest. 429768018669000The periodic table is ordered into periods and groups. A row of elements across the periodic table is calleda a period
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Development of the periodic table ➢ The elements in the periodic table have been arranged in the order of the number of protons (a.k.a. atomic number) The next significant stage in the development of the periodic table was discovered by came from John Newlands. He arranged the known elements in order of their atomic masses. He introduced the ‘law of octaves’ which meant that every eighth element had similar properties. As it didn’t work for all the known elements it was therefore dismissed
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Atoms are a part of our everyday life. Even though people might not realize it‚ they contribute to more things than people may think. From small things such as a small pebble‚ to something huge‚ like a castle. They inhabit our lifes in more way than one. Atoms make up everything around us from the air we breathe to food we eat and even the stars in the sky. The average layman does not know much about the atom but in this paper I will explain what and why they are. The word atom comes from the Greek
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Models of the Atom a) Plum Pudding Model The plum pudding model imagines the atom as a positively charged entity that contains randomly dispersed (negative) electrons within it. It is called the plum pudding model because the electrons in the positively charge cloud resemble raisins in a pudding. Thomson realized that all atoms must contain electrons‚ and since the atoms had a neutral charge‚ they must also include protons. This led him and other to think of the atom as a positively charged
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