UNIT 2 Matter and chemical change REVIEW

Transcription

1 Topic 1: Exploring Matter UNIT 2 Matter and chemical change REVIEW WHMIS means: Workplace hazardous materials information system Name these symbols Dangerousy poisonous - corrosive oxidizing reactive immediate effects Compressed gas flammable & combustible biohazardous toxic & poisonous causing other effects 1. Identify the main points of the PARTICLE MODEL OF MATTER A. All matter is made of particles B. The particles are always moving C. The particles have spaces between them D. There is attraction between the particles E. Particles are affected by temperature (ie) particles move faster when heated or move slower when cooled. 2. Describe each state of matter and the action of the particles in that state. A. Solid Particles have a strong attraction to each other and are very close together B. Liquid Particles have an attraction to one another but the particles are not as close as they are in a sold (they are moving quicker) C. Gas Particles don t have a strong attraction and the particles are spaced very far apart and are moving very fast. 3. Define the following and provide an example of each: Mechanical Mixture: A mixture that contains two of more VISIBLE parts (like a granola bar or a chocolate chip cookie) Colloid A mixture that contains fine particles evenly distributed throughout a second substance and WILL NOT SEPARATE! (fog) Emulsion A special but cloudy colloid (like milk, mayonnaise or salad dressing) Suspension A suspension is made of large particles that are uniformly mixed but will separate if left undisturbed. Suspensions can be separated by filtering and will scatter light. Flour is an example of a suspension. Compound Two or more atoms that are chemically bonded to one another (example: NaCl table salt)

2 Element Substances composed of one type of atom; the smallest unit of matter that retains its physical and chemical properties (example helium, sulfur, anything else on the periodic table) Heterogeneous Mixture A mixture that contains two of more VISIBLE parts; it is the same as a mechanical mixture (ex. granola bar or a chocolate chip cookie, or granite) Homogeneous Mixture A mixture where the particles ARE uniformly scattered (also called a solution) (ex. Sea water, air) Topic 2: Changes in Matter 1. What are the SEVEN clues that describe change as being chemical? 1. A color change occurs 2. A precipitate is formed 3. Gas bubbles are produced 4. Heat is absorbed or released 5. A new substance with NEW properties is formed 6. The starting substance is used up 7. The change is difficult to reverse 2. Name 2 qualitative physical properties and 2 quantitative physical properties. QUALITATIVE Color, taste, smell, texture, state, malleability, ductility QUANTITATIVE Melting point, boiling point, density, viscosity, solubility Topic 3: What are elements? 1. Define and explain the conservation of mass In a chemical change, the total mass of the new substances is always the same as the total mass of the original substances. Think of the balloon lab! 2. Explain John Dalton s Atomic Theory 1. All matter is made up of small particles called atoms 2. Atoms cannot be created, destroyed, or divided into smaller particles 3. All atoms of the same element are identical in mass and size. 4. Compounds are created when atoms of different elements link together in definite proportions 3. Describe and draw Ernest Rutherford s model of the atom Rutherford Thought the entire mass of an atom was in the center of the atom and the rest of the atom was empty space. He was the first to define protons and electrons. 4. Describe and draw Niels Bohr s model of the atom Bohr Pictured the atom like a mini solar system 5. Describe and draw the electron cloud model of the atom De Broglie and Schrodinger the electron cloud surrounded the nucleus and contained the region that the electrons were most likely to be found; they also thought that the behavior of electrons was similar to that of waves.

3 Topic 4: Classifying Elements 1. Describe each chemical family and explain how it is represented in the Periodic Table Chemical Family Description Table Representation Metalloids Non-Metals Alkali Metals Alkaline Earth Metals Noble Gases Halogens Topic 5: The Periodic Table Metalloids react as metals in some situations and non-metals in other situations. Non-metals are gases, solids and ONE is a liquid (bromine). Non-metals do NOT conduct electricity These elements are very reactive with water. (Remember the videos) Group 1 on the periodic table; all have a charge of 1+ These elements are not as reactive as the Alkali metals. Group 2 on the periodic table; all have a charge of 2+ Outer energy level is full of electrons this makes these gases stable. Are used to make fluorescent lighting (think neon signs); have no charge Halogens are usually found as compounds because they react with just about every other element. Halogens are extremely corrosive and harmful. Non-metals. 1- charge. elements 5, 14, 32, 33, 51 and 52 Follow the staircase the separates the metals from the non-metals They are found on the right hand side of the staircase elements 3, 11, 19, 37, 55 and 87 Group 1 is the first column on the left hand side of the table elements 4, 12, 20, 38, 56 and 88 Group 2 is the second column on the left hand side of the table. elements 2, 10, 18, 36, 54, and 86 Group 18 (at the far right of the periodic table) elements 9, 17, 35, 53, and 85 Group How did Dmitri Mendeleev organize the elements on the periodic table? Mendeleev made a card for each known element and on each card he put data like atomic mass, density, color, etc. in order to try to organize them into vertical columns and horizontal rows. Columns (called groups) on the periodic table have similar characteristics. 2. Explain what each of the following tells us about an element 1. Atomic number The number of protons in the nucleus of an atom (the big number above the atomic symbol on our class periodic table) a) Atomic Mass The mass of the nucleus (the red number below the atomic symbol on our class periodic table we round this number either up or down) b) Atomic Symbol This is the symbol for the element (Example: Fluorine s atomic symbol is F) c) What are the horizontal rows called? Periods d) How are the elements on the table numbered? They are numbered according to the number of protons in the nucleus (the atomic number); the number of protons is also a measure of mass; so you can also think of them as being numbered by mass.

4 Topic 6: Chemical Compounds 1. Compare the properties of molecular and ionic compounds Properties of molecular compounds - formed from only non-metallic elements - Does not form ions in solutions; may or may not be soluble - Usually does not conduct electricity - Solid, liquid or gas at room temperature - low melting point Properties of ionic compounds - formed from metallic and non-metallic elements - Forms ions in a solution; may or may not be soluble - Conducts electricity - Solid at room temperature - high melting point 2. What are the rules for naming molecular and ionic compounds? MOLECULAR: 1. Write the entire name of the first element. 2. Change the ending on the name of the second element to ide 3. Use a prefix to indicate the number of each type of atom in the formula: (mono one, di two, tri three, tetra four, etc) on both the first and second element IONIC: 1. Write the entire name of the first element. 2. Change the ending on the name of the second element to ide 3. Use subscripts (little numbers) to indicate how many of each atom there are in the compound. 3. How are ions formed? Ions are formed when atoms either gain or lose electrons. Metals will lose electrons and non-metals will gain electrons. A metal will give up its electrons to a non-metal who will accept them. When this transfer of electrons occurs, an ionic bond will form creating a chemical compound. 4. What is the charge of the following elements? Silicon 1- Nitrogen 3- Chlorine 1- Calcium 2+ Potassium 1+ Lithium Write the chemical formula for each of the following compounds (be sure to make sure the charges balance!) Aluminum oxide Al 2O 3 Beryllium sulfide BeS Calcium nitride Ca 3N 2 Sodium chloride NaCl Magnesium oxide MgO Lithium phosphide Li 3P

5 7. Fill in the following chart. Chemical Formula Ionic or Molecular Name NaCl ionic Sodium chloride CO 2 molecular Carbon dioxide SF 2 molecular Sulfur difluoride MgF 2 ionic Magnesium fluoride CaO ionic Calcium monoxide Silicon tetrachloride 6. How do you tell the difference between ionic and molecular compounds? Ionic compounds will have a non-metal (from the right hand side of the staircase) and a metal (from the left hand side of the staircase. Molecular compounds will have TWO non-metals (both from the right hand side of the staircase). 7. Draw a Bohr diagram for each of the following elements: LITHIUM, HELIUM, MAGNESIUM and OXYGEN. Topic 7 Chemical Reactions 1. Write a word equation for the corrosion of iron. Iron oxide Iron + Oxygen + water 2. Explain the difference between an Endothermic and Exothermic reaction. Give an example of each Endothermic reactions are reactions that BREAK chemical bonds and ABSORB energy (Cold packs) Exothermic reactions are reactions in which chemical bonds FORM and that RELEASE heat (Hot Packs) 3. What is a catalyst and how does it work? A catalyst is something that increases a reaction rate without be used up itself (example temperature can increase the rate at which bananas ripen) 4. What are two ways you can help protect metals from corrosion? 1. Apply a thin coat or pain and/or clear coat 2. Apply a thin coat of zinc (galvanization) 5. What are FOUR factors that change the speed of a reaction? 1. Temperature 2. Stirring 3. Grinding up a solid first 4. Adding a catalyst