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WORKSHEET #1 Dougherty Valley HS Chemistry Physical/Chemical Prop’s and ∆’es 1. A physical property is observed with the senses and can be determined without destroying the object. Examples of physical properties include mass, shape, color, odor, length. In a physical change, the original substance still exists. It has only changed form. 2. A chemical property indicates how a substance reacts with something else. In a chemical change, a new substance is produced. Energy changes always accompany chemical changes. Chemical changes are always accompanied by physical changes. 3. Which of the following processes are physical changes? Which are chemical changes? a. combustion e. evaporation i. boiling b. melting f. filtration c. dissolving g. fermentation d. metabolism h. distillation j. electrolysis k. decomposition Identify the following properties as physical or chemical. Physical Chemical Blue color Density Flammability Solubility Supports combustion Sour taste Melting point Physical Chemical Odor Luster Neutralize an acid Boiling point Hardness Reacts with acid to form H2 Reacts with water to form a gas 4. Classify the following examples as physical or chemical changes. a. Sodium chloride dissolves in water ______________________ b. Hydrochloric acid reacts with sodium hydroxide ______________________ to produce a salt, water, and heat. c. A pellet of sodium is sliced in two pieces. ______________________ d. Water is heated and changed to steam. ______________________ e. Potassium chlorate decomposes to potassium chloride and oxygen gas. f. Iron rusts. ______________________ g. Ice melts. ______________________ h. Acid on limestone produces carbon dioxide gas. ______________________ i. Wood rots. ______________________ j. cracking an egg ______________________ k. bake a cake ______________________ ______________________ WORKSHEET #2 WORKSHEET ON CHEMICAL VS PHYSICAL PROPERTIES AND CHANGES Keep this in your binder as a study guide! You will have a quiz on this next class! Background: Keeping the difference between physical and chemical properties as well as changes can be a challenge! This worksheet will help you do this. First, use the book to define the following terms. VOCABULARY WORD DEFINITION Physical Property Physical Change Change in which the identity of the substance does NOT change Chemical Property Chemical Change Part One: Physical or Chemical Property? Fill in the chart using the vocabulary words or phrases provided. Vocabulary words Boiling point Ability to rust Melting point Brittleness elasticity Flammability Density Transparency Reactivity with vinegar ductility Each word is used once. Define the word when done! Chemical Property↓ Definition • The ability to burn • Reacts with oxygen to produce rust Physical Property↓ Part Two: 1. 2. 3. 4. 5. 6. 7. 8. 9. Definition • The property of letting light pass through something Physical or Chemical Change? Indicate with a ‘P’ or a ‘C’ which type of change is taking place. ____________ glass breaking ____________ hammering wood together ____________ a rusting bicycle ____________ melting butter ____________ separate sand from gravel ____________ bleaching your hair ____________ frying an egg ____________ squeeze oranges for juice ____________ melting ice 10. 11. 12. 13. 14. 15. 16. 17. 18. ____________ mixing salt and water ____________ mixing oil and water ____________ water evaporating ____________ cutting grass ____________ burning leaves ____________ fireworks exploding ____________ cutting your hair ____________ crushing a can ____________ boiling water WORKSHEET #3 Dougherty Valley HS Chemistry Classification of Matter WS Directions: On a separate sheet of paper, design a classification scheme for the following. There may be many ways to accomplish this. Find one that makes sense to you: A B C D E F G H I J K L M N O P WORKSHEET #4 Dougherty Valley HS Chemistry Atomic Number and Mass Number Directions: Complete the following chart and answer the questions below: Element Name carbon Atomic Number Number of Protons Number of Neutrons Number of Electrons Mass Number 12 8 8 hydrogen 1 6 hydrogen 14 2 nitrogen 14 1 92 2 146 cesium 82 11 12 47 tungsten 108 110 45 24 80 52 89 silver 152 107 76 114 Use the backside of this sheet to answer the following questions. [1] How are the atomic number and the number of protons related to each other? Support. [2] How do the number of protons, number of neutrons, and the mass number relate to each other? Explain. [3] What is the one thing that determines the identity of an atom (that is, whether it is an oxygen atom or a carbon atom, etc.)? Support. Dougherty Valley HS Chemistry Atomic Structure Practice [1] Name: Date: Period: WORKSHEET #5 The 3 particles of the atom are: a. ______________________ b. ______________________ c. ______________________ Their respective charges are: a. ______________________ b. ______________________ c. ______________________ [2] The number of protons in one atom of an element determines the atom’s ______________________, and the number of electrons determines ______________________ of and element. [3] The atomic number tells you the number of ______________________ in one atom of an element. It also tells you the number of ______________________ in a neutral atom of that element. The atomic number gives the “identity “of an element as well as its location on the Periodic Table. No two different elements will have the ______________________ atomic number. [4] The ______________________ of an element is the average mass of an element’s naturally occurring atom, or isotopes, taking into account the ______________________ of each isotope. [5] The ______________________ of an element is the total number of protons and neutrons in the______________________ of the atom. [6] The mass number is used to calculate the number of ______________________ in one atom of an element. In order to calculate the number of neutrons you must subtract the ______________________ from the ______________________. [7] [8] [9] Give the symbol and number of protons in one atom of: Lithium __________________ Bromine __________________ Iron __________________ Copper __________________ Oxygen __________________ Mercury __________________ Krypton __________________ Helium __________________ Give the symbol and number of electrons in a neutral atom of: Uranium __________________ Chlorine __________________ Boron __________________ Iodine __________________ Antimony __________________ Xenon __________________ Give the symbol and number of neutrons in one atom of: (To get “mass number”, you must round the “atomic mass” to the nearest whole number) Show your calculations. Barium __________________ Bismuth __________________ Carbon __________________ Hydrogen __________________ Fluorine __________________ Magnesium __________________ Europium __________________ Mercury __________________ [10] Name the element which has the following numbers of particles: a. 26 electrons, 29 neutrons, 26 protons _____________________ b. 53 protons, 74 neutrons _____________________ c. 2 electrons (neutral atoms) _____________________ d. 20 protons _____________________ e. 86 electrons, 125 neutrons, 82 protons (charged atom) _____________________ f. 0 neutrons _____________________ [11] If you know only the following information can you always determine what the element is? (Yes/No). a. number of protons ___________ b. number of neutrons___________ c. number of electrons in a neutral atom___________ d. number of electrons___________ [12] X = element symbol A = mass number [# of protons (p) + # neutrons (n)] Z = atomic number [# of protons] N = # of neutrons A-Z=N A typical isotopic symbol takes this form: ex. The isotopic symbol for Fluorine would be Fill in the missing items in the table below. Name Symbol Z A #p #e #n Isotopic Symbol #p #e #n Isotopic Symbol #e #n Isotopic Symbol Na 17 Potassium Fill in the missing items in the table below. Name Symbol P Z A Iron 53 Fill in the missing items in the table below. Name Silver Symbol Z 36 W A #p ATOMIC WEIGHTS STUDENT PRACTICE Look at the atomic weights of a few different elements on your periodic table. Do you notice that very few of the elements have atomic weights that are close to being nice whole numbers? NOTE: The numbers in each of the following problems have been made up. If we used actual percentages and masses of isotopes then you could simply look up the atomic weight of the element on the periodic table. Do you know why this is? After all, for our purposes, the mass of both the proton and the neutron are almost exactly 1, and in chemistry we usually ignore the mass of the electron because it is so very small. 1. Suppose that there were two isotopes of Sodium. 28% of the naturally occurring sodium atoms had a mass of 22, and 72% atoms had a mass of 23. What would the average atomic weight of sodium be? Why then, if the mass of the atom comes mainly from the protons and neutrons it contains, don’t the atomic weights of the all come out to be nice whole numbers? The reason is this; the atomic weights given on your tables are “weighted averages” of the weights of the different naturally occurring isotopes of the element. Let’s look at an example. Approximately 75% of the chlorine atoms found in nature have a mass of 35. The other 25% have a mass of 37. What should we report as the atomic weight for chlorine? What we do is to take the “weighted average” of these isotopes. We multiply 75% times 35 and then add that to 25% times 37... 2. Suppose that there were two natural isotopes of Copper. 80% of the atoms had a mass of 63, and 20% of the atoms had a mass of 65. What would that average atomic weight of copper be? [(.75)(35)] + [(.25)(37)] = 26.25 + 9.25 = 35.5 amu In cases where there are three known isotopes you would simply multiply each mass number by the % (expressed as a decimal) of the atoms with that mass and then add the products together. 3. Suppose that a new element (E) were discovered that existed as three natural isotopes. 25% of the atoms had a mass of 278, 38% had a mass of 281, and the remainder had a mass of 285. What would be listed as the atomic weight of this element?