Learn about the importance of physical and chemical properties in material selection through examples and explanations. Discover how properties like color, density, and odor differentiate materials for various uses. Explore concepts such as physical and chemical changes and their impact on material behavior. Gain insights into the properties of metals, nonmetals, and metalloids.
01 / 55Understanding Physical and Chemical Properties for Material Selection
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Understanding Physical and Chemical Properties for Material Selection
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HW 1 Read & take notes on sections A.1 (pg . 110) & A.2 (pg. 111) , being certain to address all the examples in section A.2
A.1 – Properties Make the Difference Physical properties: • Color • Density • Odor May be determined without altering chemical make-up Ex. 8.96 g/cm3 2.06 g/cm3
A.2 – Physical & Chemical Properties S.P. 1: Copper compounds are often blue in color S.P. 2: Oxygen gas supports the burning of wood PHYSICAL PROPERTY CHEMICAL PROPERTY
A.2 – Physical & Chemical Properties(continued) 3. N2 which is a relatively nonreactive element at room temp. , can form NO2 at high temperatures of an auto engine. 4. Milk turns sour if left too long at room temperature CHEMICAL PROPERTY CHEMICAL PROPERTY
A.2 – Physical & Chemical Properties(continued) 5. Diamonds are hard enough to be used as coating for drill bits. 6. Metals are typically ductile (can be drawn into wires) PHYSICAL PROPERTY PHYSICAL PROPERTY
A.2 – Physical & Chemical Properties(continued) 7. Leavened bread dough increases in volume if it is allowed to rise before baking. 8. Unreactive argon gas, rather than air, is used to fill many light bulbs to prevent the metal filament wire inside the bulb from being destroyed through oxidation. CHEMICAL PROPERTY CHEMICAL PROPERTY
A.4 – The Chemical Elements(continued) Two major classes of elements are metals and nonmetals. Several elements have properties of both and are called metalloids.
A.5 – Metal or Nonmetal? See pgs 115 – 117 By the end of class – answer how you did on the predictions AND questions 1-4 on pg 117.
A.5 – Metal or Nonmetal? (Lab follow up) Common lab issues: Make certain you answer the question being asked. Restate the question in the form of a statement and ADD your information. Make it a goal to show me that you have actually thought about the question, rather than prove you never even considered it. (example next slide)
No shoveling please . . . Q – How did you do on your predictions? (tell me below) Student answer: “On my predictions I made the common sense answer but there was a few more per question and a few surprising ones but relatively well.”
As apposed to the following Q – How did you do on your predictions? (tell me below) Student answer: “Malleable * I got 2/4 correct. Me – Mg & Zn, results Al, Cu , Mg ,Zn
HW 4 Pre-read and take notes on A.6 And make certain you have your element cards with you when you come to class next day.
A.6 – The Periodic Table(A Brief History) By mid-1800s, chemists identified ~60 elements. Five were nonmetals, gasses at room temperature. hydrogen (H) Two liquids were also known. oxygen (O) Metal : mercury (Hg) nitrogen (N) Nonmetal : bromine (Br) fluorine (F) chlorine (Cl) Scientist tried to place elements near one another based on similar properties.
A.8 – The Pattern of Atomic Elements Refresher : Atoms consist of sub-atomic particles Protons , small positively charged particles and neutrons, particles with no charge make up the nucleus of an atom. Electrons are a negatively charges particles found in varying energy levels surrounding the nucleus.
A.8 – The Pattern of Atomic Elements(continued) The number of protons in an atom is called the atomic number. For the example to the right the value would be _____ Mass number is the total number of protons and neutrons in the nucleus of an atom. Example to the right the value would be ____
A.8 – The Pattern of Atomic Elements(continued) While all atoms of particular elements have the same number of protons, they contain different number of neutrons. Example (from book) , carbon (C) always has 6 protons, but may contain 6,7, or 8 neutrons – these are called isotopes.
A.8 – The Pattern of Atomic Elements(continued) So why are the atomic masses we see on the periodic table not integers (whole numbers)? They take into account the weighted average of the atomic masses of the naturally occurring isotopes. Candium Isotopes
A.9 – Periodic Variation in Properties See pgs 122-123 Graphing lab we’ll do together. After graphing the data , please answer questions 1,3 & 4 on pg 123
HW 7 Read & take notes on sections A.10 and answer A.11
A.11 – Predicting Properties(continued) 1) Given, the b.p. of argon (Ar) is -186°C and of xenon (Xe) is -112°C. Estimate the b.p. of krypton (Kr). Krypton should have a boiling point between argon 87 K and xenon 161 K of about 124 K – actual = 120 K.
A.11 – Predicting Properties(continued) 2a) Given, the m.p. of potassium (K) is 337°K and of cesium (Cs) is 302°K. Estimate the m.p. of rubidium (Rb). Actual = 312 K 2b) Would the m.p. of sodium (Na) be higher or lower than (Rb) , explain.