In the series of group 5A hydrides, of general formula MH3, the measured bond distances are P一H, 1.419 Å; AsH, 1.519 Å; SbH, 1.707 Å. (a) Compare these values with those estimated by use of the atomic radii in Figure 7.6. (b) Explain the steady increase in MH bond distance in this series in terms of the electronic configurations of the M atoms.
Chapter 6 end: Testrapods I. four-legged; handful of air-breathing organisms that have returned to life in the sea II. hypoosmotic to sea water III.two groups are ectothermic— amphibians and reptiles IV. vertebrates— relative of coelacanth; moved to land 350 may V. adaptations to breathing, movement, and desiccation A. then moved back to the ocean 1. turtles still lay eggs on land 2. whales completely adapted VI. amphibians— only one A. highly permeable skin also takes in salt B. Southeast Asian crab-eating frog— lives in estuaries/mangroves C. tadpole— osmoregulates like a teleost (osteichtyes) D. adults— osmoregulate like an elasmobranch VII.reptiles— 7,000 species A. most adapted to living on land 1. scales for water loss prevention 2. leathery eggshell for water loss prevention B. sea turtles— all are threatened or endangered 1. endangered— species under direct threat of survival a) critical number— once the species reaches a certain number, there is no hope of replenishing the population 2. threatened— species may become endangered 3. upper shell= carapace 4. lower shell= plastron 5. ribs are fused to shell 6. strong jaws— except for leatherback 7. poikilotherms— body temp ﬂuctuates with the environment (except for leather back because they are so large) 8. breed at sea a) internal fertilization— males use long tails and claws to grip b) females can store sperm; leads to multiple paternilization c) breed every 2-4 years with several clutches every breeding year (1)clutches= 120 eggs with incubation period of 60 days d) deposit eggs near dune line e) temperature dependent sex determination (1)pivotal temperature— generates 50/50 distribution (2)higher than pivotal= more females (3)lower than pivotal= more males 9. K-selected species— like humans a) niche specialists 10. species: a) Kemps Ridley (1)smallest at 100cm and 100 pounds (2)thought to be a hybrid because they couldn't ﬁnd their nesting locations (3)Atlantic coasts (4)synchronized nesting b) Leatherback (1)largest, reaching over 6ft and 1000 pounds (2) weak jaws— feed on jellies; can dive deep to prey (a) gum-like projections on bottom and roof of mouth c) Hawksbill (1) tropical (2) feeds on coral, sponges, and invertebrates (3) hunted four beauty d) loggerhead (1) most abundant in US waters (2) genetic populations— Northern, Southern; possible gulf too (3) nest in warm and subtropical C. Indo-Paciﬁc Crocodile 1. latterally ﬂattened tail 2. opens mouth underwater 3. salt glands- “crocodile tears” 4. largest can be 30 ft 5. not fully adapted to marine existence D. Marine Iguana 1. Galapagos Islands 2. 7 subspecies— close relative to land iguana 3. eat algae 4. “sneezing” = salt excretion 5. webbed feet with long claws 6. can submerge up to 15 meters or 30 minutes E. Sea Snakes 1. 55 species; only found in the Indian and Paciﬁc Oceans 2. latterally ﬂattened body with paddle-like tail 3. most are 3-4 feet as adults 4. evolved from land snakes a) cobra relatives— live birth at sea b) sea kraits— lay eggs on land VIII.daptations to sea water A. homeostasis— constancy in the internal environment; outside conditions change but inside does not B. enantiostasis— constancy in the internal functions; internal conditions can change, but the function are not hindered C. physiological processes arise through evolution D. oxygen 1. required by almost all organisms 2. some environments are low oxygen— a) low tide for intertidal animals b) within sediment c) oxygen minimum layers in water column d) seasonal oxygen changes in estuaries: hypoxic zones, “dead zones” 3. consumption rate increases in animals with more activity 4. weight-speciﬁc consumption decreases with over all weight increase a) surface area to volume ratio 5. in low oxygen, organisms can have blood pigments that increase capacity for transport 6. respiratory organs a) short pathways for oxygen to diffuse b) extensive vascularization (1) lots of blood c) large surface area d) thin ﬁlm of water for oxygen diffusion e) surface area of gills is proportional to activity