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Physical Properties

Physical Properties. A trait we can observe w/o changing the identity of the substance. EXAMPLES: Color Shape Dimensions (size) Texture Taste Temperature Melting Point Density Smell Freezing Point Mass. Chemical Properties.

cameron-richard
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Physical Properties

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  1. Physical Properties A trait we can observe w/o changing the identity of the substance. EXAMPLES: • Color • Shape • Dimensions (size) • Texture • Taste • Temperature • Melting Point • Density • Smell • Freezing Point • Mass

  2. Chemical Properties A trait we can observe by changing the identity of the substance. EXAMPLES: • Flammability • Decomposable • Digestible • Toxicity • Ability to Oxidization • Reactivity/Inert

  3. Physical Change A change that affects only physical properties and does not change the identity of the substance. EXAMPLES: • Rip • Crumble • Wet • Throw • Draw • Fold • Kick • Mix

  4. Chemical Change A change that alters the identity of the substance. EXAMPLES: • Eating/Digesting • Burning • React w/ acid or anything • Decompose • Oxidization

  5. Elements, Compounds, and Mixtures Element: substances that cannot be separated by chemical or physical means. Atom: smallest unit of an element. Compound: substance made of 2 or more elements. It can only be separated by chemical means. Molecule: smallest unit of a compound. Mixture: A combination of substances that are not chemically combined. Can be separated by physical means. Homogeneous: looks the same throughout. Heterogeneous: composed of different parts.

  6. Density A ratio of mass to volume. D= m/v D=Density g/ml=g/cm^3 V=Volume milliliters=cm^3 M=Mass grams

  7. Example Problem: Density A rock has a mass of 8g. When Bob puts it in a graduated cylinder it displaces 4L of water. What is the density?

  8. ANSWER D=M/V D=8g/4L D=2L

  9. Scientific Notation • A way of writing numbers that are too big or too small to be conveniently written in decimal form. EXAMPLES: 300 = 3×102 6,720,000,000 = 6.72×109

  10. Sig Figs • Multiplication and Division Rules: The number of sig figs in your answer is the same as the least number of sig figs in your measurements. EX: find the area from these measurements. 505cm long = 3 sig figs10cm wide = 1 sig fig A = L x W A= 505 x 10 = 5050cm2 A= 5,000cm2

  11. Extra Practice Find the rate of measurement. 250.0mL 0.25s

  12. ANSWER Find the rate of measurements. 250.0 mL = 3 sig figs 0.25s = 2 sig figs 250.0/0.25 = 1000mL/s  1.0 x 103

  13. Sig Figs Continued • Addition and Subtraction Rules: The estimated number in your answer is located in the same place value column as the estimated number in the measurement’s that is farthest to the left. EX: 101.0g + 10.5g 111.5g  112 g

  14. Extra Practice 212.25C and 12.3C

  15. ANSWER 212.25C + 12.3C 199.95C  200.0C

  16. Accuracy/Precision

  17. Accuracy/Precision Continued • the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.

  18. Quantitative/Qualitative • Quantitative: Is expressed or related to in terms of quantity as in numbers. • Qualitative: Related to or involving quality or kind.

  19. Ionic Compound • Occurs between One Metal and Non-Metal • Crystilanial Solids (Made of Ions) • High Melting and Boiling points • Conduct with electricity when melted • No Definite shape

  20. Covalent Compound • Occurs Between Two Metals • Gases, Liquids, Soft Solids (Made of Molecules) • Low Melting and Boiling points • Poor electrical conductors • Define Shape

  21. Periodic Table • To the left of the red line are non-metal • To the right of the red line are metals

  22. Example …is which type of bond? • NaBr • HCL • AgCL • C2S

  23. Answers 1. Ionic Bond- Na is a non-metal, Br is a Metal 2. Ionic Bond- H is a non-metal, Cl is a metal 3. Ionic Bond- Ag is a non-metal, Cl is a metal 4. Covalent Bond- C is a metal, S is a metal

  24. To Tell The Difference • Look at periodic table • Locate your elements • Look for the stair case in the periodic table • Under elements B,SI,AS,TE,AT

  25. Isotopes • An isotope is an atoms with the same number of protons, but differing numbers of neutrons • Isotopes are different forms of a single element • Different Atomic Mass

  26. How To Calculate Average Atomic Mass • 1. Convert the percentages into decimals. (This percentage is known as its relative abundance or percent abundance) • 2. Multiply the percentage of each isotope by its respective mass • 3. Add the numbers from step two together

  27. Example

  28. Answer • This is the solution for carbon: (12.000000) (0.9890) + (13.003355) (0.0110) = 12.011 amu

  29. Basics • Find your element on the Period Table • element's atomic number and atomic weight. • atomic number is the number in the upper left corner • atomic weight is the number on the bottom

  30. Protons and Electrons • The atomic number is the number of protons in an atom of an element. • krypton's atomic number is 36, so an atom of krypton has 36 protons • Electrons have the same quantity as protons

  31. Neutrons • Mass Number = (Number of Protons) + (Number of Neutrons) • For krypton, this equation becomes: • 84 = (Number of Protons) + (Number of Neutrons) • 84 = 36 + (Number of Neutrons) • NUETRONS = 48

  32. Summary • For any element: • Number of Protons = Atomic Number • Number of Electrons = Number of Protons = Atomic Number • Number of Neutrons = Mass Number - Atomic Number

  33. Ions • Ions are formed when an atom gains or loses electrons and gets charged • If an atom gains electrons, number of electrons are higher than protons • an atom gets negatively charged • Similarly if an atom loses electrons the total number of protons become more than the number of electrons • atom becomes positively charged

  34. What is an ion? • Ion • electrically charged atom or atom group: • an atom or group of atoms that has acquired an electric charge by losing or gaining one or more electrons

  35. Knowing the charge

  36. So… • Determine the charge of each element when present in an ionic compound.Use the table above to determine these charges. For example, O = -2, Rb = +1. • Use the appropriate number of each ions such that: • The sum of all charges adds up to zero. • The simplest ratio of ions is used. • For example, if magnesium (Mg) and bromine (Br) are mixed: • Metal (Mg) + Non-metal (Br) IS an ionic compound. • Mg ⇒ Mg+2 and Br ⇒ Br-1 • For the final steps: • One +2 ion is exactly balanced by two -1 ions. • 2:1 is the simplest possible ratio. • Thus, the formula of the ionic compound formed is MgBr2

  37. Alpha • There are three primary types of radiation: • Alpha - these are fast moving helium atoms. They have high energy, but due to their large mass, they are stopped by just a few inches of air, or a piece of paper.

  38. Beta • These are fast moving electrons. Since electrons are lighter than helium atoms, they are able to penetrate further, through several feet of air, or several millimeters of plastic or less of very light metals.

  39. Gamma • Gamma - these are photons, just like light, except of much higher energy, X-Rays and gamma rays are really the same thing, the difference is how they were produced. Depending on their energy, they can be stopped by a thin piece of aluminum foil, or they can penetrate several inches of lead

  40. Review • A nuclear reaction can be described by an equation, which must be balanced. • The symbol for an atom or atomic particle includes the symbol of the element, the mass number, and the atomic number. • The mass number, which describes the number of protons and neutrons, is attached at the upper right of the symbol. • The atomic number, which describes the number of protons in the nucleus, is attached at the lower left of the symbol

  41. Electron Configurations Diagram way/ Orbital notation 1.List all of the orbitals with boxes 2.Find out how many electrons are in the element 3. Electrons fill the lowest energy levels first (follow diagonal rule) 4.Reminder* Only 2 electrons fit into a degenerate orbital Long way/List way 1.Write out the orbitals 2.Depending on the orbital write the amount of electrons in the exponent 3.Do this until your configuration is complete 4.Reminder * S orbital- up to 2 electrons, P orbital- up to 6, D orbital- up to 10, F orbital- up to 14 Noble gas notation 1.Refer to noble gas before element 2.Write noble gas in brackets 3.Figure out next orbital and fill like usual

  42. Sample Problem: Be- Beryllium Write the: Orbital Notation List way Noble gas notation

  43. Answers to Sample Problem: Orbital Notation: 2s 1s Electron Configuration: 1s^2 2s^2 Noble Gas: [He]2s^2

  44. Wavelength, Energy & Frequency Calculations Wavelength- distance from crest to crest of a wave, one full cycle of a wave-- measured in meters Frequency- how often a wave passes per second-- measured in 1/s per second As wavelength gets smaller, wave frequency gets larger Equation: c= speed of light= 3.0x 10^8 m/s Energy of a wave is related to its frequency: E= energy in joules h= plank's constant= 6.626 x 10^-34 Joules/second

  45. Sample Problem: Ex. A light at a stoplight has a wavelength of 5m 1. What is the frequency of light? 2. What is the energy of light?

  46. Answers to Sample Problem: Answers 1. wavelength= speed/frequency 5 m= 3.0 x 10^-8 m/s ___________ frequency frequency= 3.08 x 10^-8/ 5 frequency= 6.16 x 10^-9 1/s 2. E= hv h= 6.6 x 10^-34 J x S E= (6.6 x 10^-34)(6.16 x 10^-9) E= 4.07 x 10^-42 J

  47. Trends Electronegativity-chemical property describing tendency of an atom to attract electrons to itself, which is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus. Ionization Energy- describes the amount of energy required to remove an electron from the atom or molecule. Atomic Radius- measure of the size of an element's atoms.

  48. Electronegativity, Ionization Energy & Atomic Radius Trends

  49. Periodic Table Families and Periods Periods- go across the table; there are 7 Groups- go vertically down the table; 8 are classified Families- represent elements of the same nature ex. group 8 is called the Noble Gas family because all of these elements have something in common, they all have complete valence shells

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