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CONCEPT: MATTER Chemistry is the study of matter and the changes it undergoes, with the being its basic functional unit. When two or more of these elements chemically bond together they form an independent structure called a molecule. Classification of Matter Under appropriate conditions of pressure and temperature, most substances can exist in 3 states of matter:, and. have a fixed shape and volume. take up the shape and volume of a container. conform to the shape of a container, but not the volume. Microscopic Explanation for the Behavior of Gases, Liquids and Solids Gas Liquid Solid Assumes the and of its container. Assumes the of the portion of its container it occupies, but not the. Maintains a fixed and compressible compressible compressible Viscosity Viscosity Viscosity Viscous Viscous Viscous Page 2
CONCEPT: GROUP NAMES AND CLASSIFICATIONS Ever wonder where did this periodic table ever come from? At the end of the 18 th century, Lavoisier compiled a list of the 23 elements known at the time. In 1869, Dmitri Mendeleev coined the term Periodic Table. Today the total is 114 and still counting! Now, to understand chemistry fully it will be imperative that you memorize and learn the different portions of the Periodic Table. Phase Differences At room temperature (between 20 o C to 25 o C), all elements are except: Mercury and bromine are. Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine and the Noble Gases are. Page 3
CONCEPT: CHARGE DISTRIBUTIONS OF THE PERIODIC TABLE A majority of the elements on the periodic table are reactive because they all want to be like the. They have the perfect number of electrons in their outer atomic shells. 1. Metals tend to electrons to become positively charged ions called. Metals that have ONLY one charge are referred to as metals. Metals that have MORE THAN one charge are referred to as metals. 2. Nonmetals tend to electrons to become negatively charged ions called. Page 4
CONCEPT: ELEMENT SYMBOLS Some of the names and symbols for the elements are easy to recognize like Aluminum is Al, but some others aren t. EXAMPLE 1: Identify the elements by their given symbols. a. Au b. Hg c. Pb d. Fe e. Ag Some elements exist in nature connected to their exact double. We call these chemical Siamese twins. To recall them just remember this funny phrase: Have No Fear Of Ice Cold Beer Some elements exist in nature as monoatomic elements such as &. Some elements exist in nature as polyatomic molecules such as &. Page 5
CONCEPT: ATOMIC MASS Whether you call it atomic mass or weight both terms tell us the combined mass of the protons and neutrons in an element. The atomic masses listed for the elements on the periodic table are the of their isotopes. Isotopes are elements with the number of protons, but number of neutrons. Atomic Mass = [(Mass of Isotope 1) x (Fractional Abundance 1)] + [(Mass of Isotope 2) x (Fractional Abundance 2)] EXAMPLE 1: Antimony has two common isotopes. If one of the isotopes 121 Sb has an isotopic mass of 120.9038 amu and a natural abundance of 57.25%, what is the isotopic mass (to 4 significant figures) of the other isotope? The atomic mass of antimony is 121.8 g/mol. EXAMPLE 2: The atomic mass of an imaginary element A is 251.7 amu. If element A consists of two isotopes that have atomic masses of 250 and 253 respectively, what is the natural abundance of each isotope? Page 6
CONCEPT: STRUCTURE OF THE ATOM We learned that the basic functional unit in chemistry is the. Now it s time to go into an atom to figure out its components: subatomic particles. In the center of an atom there is the, It contains the subatomic particles: and. Spinning around it we find the third subatomic particle: the. PROTONS are charged subatomic particles. ELECTRONS are charged subatomic particles.! NEUTRONS are charged subatomic particles. ATOMIC NUMBER equals the number of and determines of an element. ATOMIC MASS equals the number of in an element. EXAMPLE: Identify the unknown element. a. Element X (8 protons, 8 electrons, 8 neutrons) b. Element Y (35 protons, 36 electrons, 46 neutrons) c. Element Z (12 protons, 10 electrons, 13 neutrons) Page 7
CONCEPT: MODERN ATOMIC THEORY According to the Law of in a reaction matter is neither created nor destroyed. Originated in 1789 by Antoine Lavoisier. CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g) According to the Law of all samples of a compound, no matter on their origin or preparation has the same ratio in terms of their elements. Originated in 1797 by Joseph Proust. CO 2 Mass Ratio = (12.0gC) (32.0gO) = 0.375 According to the Law of when two elements (A & B) form different compounds, the masses of element B that combine with 1 g of A are a ratio of whole numbers. Originated in 1804 by John Dalton. NO Mass Ratio = (16.0gO) (14.0g N) =1.143 NO 2 Mass Ratio = (32.0gO) (14.0g N) = 2.286 The ratio of the two mass ratios obtained then gives us a whole number: 2.286 1.143 = 2.0 Page 8
CONCEPT: MODERN ATOMIC THEORY (PRACTICE) EXAMPLE 1: A 15.39 g sample of iodine reacts with 62.92 g of chlorine to form iodine pentachloride, ICl5. If iodine pentachloride is the only product formed calculate its mass. EXAMPLE 2: Two samples sodium fluoride decompose into their constituent elements. The first sample produces 15.8 kg of sodium and 20.1 kg of fluorine. If the second sample produces 192.0 g of sodium, how many grams of fluorine were also produced? PRACTICE: Which of the following is an example of the law of multiple proportions? a. A sample of bromine (Br) contains equal amounts of its two isotopes. b. Two different samples of H2O have the same mass ratio. c. The atomic mass of sodium (Na) is 22.99 amu. d. Two different compounds composed of sulfur (S) and oxygen (O) have different mass ratios: 2.48 g O: 1 g S and 1.24 g O: to 1 g S. Page 9
CONCEPT: THOMSON CATHODE RAY TUBE EXPERIMENT J.J. Thomson s cathode ray tube experiments led to the discovery of the. Apply an Electric Field When an electric field is applied across the cathode ray tube, the cathode ray is attracted to the plate with a charge. Applying a Magnetic Field A moving charged body behaves like a tiny magnet, and it can interact with an external magnetic field. The electrons are by the magnetic field. Determining the Charge-To-Mass Ratio In 1897, JJ Thomson, an English Physicist, determined the charge-to-mass ratio of an electron by adjusting the electric field so that the deflection (θe) was the same as the deflection (θb), and was able to calculate the charge-to-mass ratio of an electron using the following equation: e / m ratio = Eθ E B 2 l Thomson determined the charge-to-mass ratio of an electron to be -1.76 x 10 8 coulombs per gram, meaning it was approximately 2000 times lighter than hydrogen, the lightest known atom. e / m ratio = Eθ E B 2 l = 1.76 108 coulombs per gram Page 10
CONCEPT: RUTHERFORD GOLD FOIL EXPERIMENT The experiment also called the Rutherford Gold Foil experiment helped to discover that any given atom had a positively charged center called the. It is there where most of the atom s mass was concentrated. Subatomic Particle Charge Mass Relative Absolute Relative (in amu) Absolute (in kg) Proton (p + ) +1 +1.60 x 10-19 C 1.00727 1.673 x 10-27 Neutron (n o ) 0 0 1.00866 1.673 x 10-27 Electron (e ) 1-1.60 x 10-19 C 5.49 x 10-4 9.11 x 10-31 Page 11
CONCEPT: MILLIKAN OIL DROP EXPERIMENT In 1913 Robert Millikan and Harvey Fletcher discovered the charge of an electron as being. The charge of an electron When an oil droplet is suspended, mass x acceleration (m x g) due to gravity is exactly counterbalanced by the electric force applied. The electric force applied equals the applied electric field E times the charge on the drop (q). Making them equal to one another: The mass of an electron By using his discovered charge and then the charge-to-mass ratio determined by Thomson s cathode ray tube experiment we are able to calculate the mass of electron. Page 12