d 2 2 1 20 e 5 4 3 f 15 5 g 40 2 4 h 3 3 1 3 5 i 2 2 1 j 20 4 k 4 1 4 l 6 3 2 5 The numbers in the upper-right corner of each cluster match the clues given on the previous page. Here are the atomic numbers and symbols and clues for the 12 entries. a 12 Mg A but tough metal, sometimes used in flares. b 1 H The most common element in a star. c 30 Zn The first metal to have both its 3d and 4s subshells filled in its ground state. d 2 He The second-most common element in a star. e 20 Ca This group-2 metal is predominant in quick lime, lime water, and limestone. f 15 P Besides oxygen and carbon, a key element in the backbone spirals of DNA. g 40 Zr In a periodic this element occupies period 5, group 4 h 3 Li This alkali metal has the strongest drive to be oxidized, measured by Eox values. i 2 He Its boiling point is a very cold 4.1 K. j 20 Ca This carbonate salt has a molar mass of 100. k 4 Be The one element in the alkaline-earth group that is not a true metal. l 6 C Graphite is one of the allotropes of this element. Next-Generation Science Standards (NGSS) Correlations Article NGSS How is Toxic? Crosscutting Concepts: Scale, proportion, and quantity Science and Engineering Practices: Developing and using models mathematics and computational thinking
about 90 minutes after you fall asleep. The table below summarizes the difference in the processes that occur during the sleep cycle. Table 1. Comparison of Physiological Changes During NREM and REM Sleep Physiological Process During NREM During REM brain activity decreases from wakefulness increases in motor and sensory areas, while other areas are similar to NREM heart rate slows from wakefulness increases and varies compared with NREM blood pressure decreases from wakefulness increases (up to 30 percent) and varies from NREM blood flow to brain does not change from wakefulness in most regions increases by 50 to 200 percent from NREM, depending on brain region respiration decreases from wakefulness increases and varies from NREM, but may show brief stoppages (apnea); coughing suppressed airway resistance increases from wakefulness increases and varies from wakefulness body temperature is regulated at lower set point than wakefulness; shivering initiated at lower temperature than during wakefulness is not regulated; no shivering or sweating; temperature drifts toward that of the local environment sexual arousal occurs infrequently increases from NREM (in both males and females) () Additional information on details of the function of the endocrine and renal systems and alimentary activity can be found at the National Institutes of Health Teacher’s Guide (see the URL above). Studies on rats show that their normal life spans of two to three years have been shortened to five months when they are deprived of REM (see section below on sleep). When deprived of all sleep, they may die in as little as three weeks. Some scientists consider lack of sleep as injurious to health as lack of food. () More on the quality of sleep and the NREM/REM cycles It is not only the nine hours of sleep before the alarm that are important for teens, but it is also the adequate quality of this sleep time that is required to produce a refreshed and alert morning wake up. There are four main stages of sleep: The Stages of Sleep
Provide decimal multiples and submultiples to make computations easier (based on man’s possessing 10 fingers). Use common prefixes across the various base and derived units, thus making the entire system more universal and more “user-friendly”. Be practical, in the sense that the base units should be close in size to customary units (again, more “user-friendly”), making adoption by nations and individuals more likely to succeed. (adapted from ) More on SI base units The SI system has only seven base units to measure length, mass, time, electric current, temperature, amount and luminous intensity. All other measurable quantities are derived from these seven base units. Because of this minimalist approach, SI is a much simpler system of measurement than any that has preceded it. The below lists the seven SI base units, the quantity they measure, their symbol, and the original (historical) and most recent (scientific) basis for the size of that unit: Quantity Measured Unit Symbol Original Basis Newest Basis Length meter m (1793) 1/10,000,000 of length of a quadrant of (North Pole to Equator); Later (1960), length of platinum-iridium alloy prototype meter (interim) Various measurements involving wave-lengths of visible emission of light from various elements (first, 1960, Kr-86); Now (1983), distance light travels in a vacuum in 1 / 299,792,458 of a second Mass kilogram kg (1793) Unit of “grave” (now obsolete), mass of 1 decimeter3 of water (1901) Mass of platinum-iridium alloy prototype kilogram Time second s (ancient) 1/86,400 of one day; Later (1956) 1/31,556,925.9747 of tropical year for January 1900 (1997) Duration of 9,192,631,770 periods of radiation corresponding to transition between two hyperfine levels of ground state of the Cs-133 atom
DERIVED QUANTITY NAME SYMBOL EXPRESSION IN TERMS OF BASE UNITS Moment of Force Newton Meter N • m kg • m2 / s2 Surface Tension Newton Per Meter N / m kg / s2 Heat Capacity, Entropy Joule Per Kelvin J / K kg • m2 / s2 / K Specific Heat, Specific Energy Joule Per Kilogram J / kg m2 / s2 Specific Heat Capacity, Specific Entropy Joule Per Kilogram Kelvin J / (kg • K) m2 / s2 / K Thermal Conductivity Watt Per Meter Kelvin W / (m • K) kg • m / s3 / K Energy Density Per Cubic Meter J / m3 kg / m / s2 Electric Charge Density Coulomb Per Cubic Meter C / m3 A • s / m3 Molar Energy Joule Per Mole J / mol kg • m2 / s2 / mol Molar Entropy Joule Per Mole Kelvin J / (mol • K) kg • m2 / s2 / mol / K () This table shows the accepted prefixes that precede the base- or derived units in the SI system, their names, symbols and number. Power of Ten Unit Name Symbol Actual Number 1024 Y 1,000,000,000,000,000,000,000,000 1021 zetta Z 1,000,000,000,000,000,000,000 1018 exa E 1,000,000,000,000,000,000 1015 peta P 1,000,000,000,000,000 1012 tera T 1,000,000,000,000 109 giga G 1,000,000,000 106 mega M 1,000,000 103 kilo k 1,000 102 hecto h 100 101 deka da 10 100 1 10–1 deci d .1 10–2 c .01 10–3 milli m .001 10–6 micro μ .000 001 10–9 nano n .000 000 001 10–12 pico p .000 000 000 001 10–15 femto f .000 000 000 000 001 10–18 atto a .000 000 000 000 000 001 10–21 zepto z .000 000 000 000 000 000 001 10–24 y .000 000 000 000 000 000 000 001
References (non-Web-based information sources) Baxter, R. Permanent Waves. ChemMatters 1993, 11 (2), pp 8–11. This article deals with what happens at the cellular and molecular level when various chemicals are applied to hair to create waves. The illustrations concerning bonding (making and breaking) and the structure of hair follicles are useful references. Raber, L. Hair Color: Chemistry to Dye For. ChemMatters 2002, 20 (2), pp 10–11. For those interested in the chemistry of dyeing hair, this article details the materials used for coloring the hair. Fruen, L. Natural, Braided, Bleached, Colored, Straight, and Curly Hair…Thanks to Chemistry. ChemMatters 2008, 26 (3), pp 15–17. Doing things to hair other than washing requires the right chemicals—think of conditioners, styling gels, and hair dyes. The ways in which hair responds to these chemicals is well documented in this 2008 article. ChemMatters Teacher’s Guide. October 2008, p 74. This section of the Teacher’s Guide that accompanies the Fruen hair article above provides extensive information on hair dyes, shampoo and hair structure. It also includes some fun facts about hair. Wood, C. The Art and Chemistry of Dyes. ChemMatters 2009, 27 (1), pp 13–15. This article deals predominantly with the dyeing of cotton and wool. It does describe the dyes and chromophores. Web Sites for Additional Information (Web-based information sources) These sites covers many of the topics listed below. Good Hair Days: A Case of Good Chemistry: . Hair Color: Research Update: . This is a nice Prezi presentation that describes many of the topics listed below: . More sites on the structure of hair This is an extensive, well written article that covers many aspect of hair, including the structure of hair, bonding and curling of hair, hair products and the bleaching and the dyeing of hair. () “Better Hair through Chemistry” is a basic, well written article about hair. It discusses the chemistry involved in the structure of hair, the characteristics of hair, and bleaching and dyeing of hair. ()