hydration shell

Examples of hydration shell in the following topics:

• Water’s Solvent Properties

  • This is referred to as a sphere of hydration, or a hydration shell, and serves to keep the particles separated or dispersed in the water.
  • Consider table salt (NaCl, or sodium chloride): when NaCl crystals are added to water, the molecules of NaCl dissociate into Na+ and Cl– ions, and spheres of hydration form around the ions.
  • When table salt (NaCl) is mixed in water, spheres of hydration form around the ions.

• Characteristics of Amniotes

  • The distinguishing characteristic of amniotes, a shelled egg with an amniotic membrane, allowed them to venture onto land.
  • Although the shells of various amniotic species vary significantly, they all allow retention of water.
  • The shells of bird eggs are composed of calcium carbonate and are hard, but fragile.
  • The shells of reptile eggs are leathery and require a moist environment.
  • The amnion protects the embryo from mechanical shock and supports hydration.

• Electron Shells and the Bohr Model

  • These orbits form electron shells or energy levels, which are a way of visualizing the number of electrons in the various shells.
  • Electrons fill orbit shells in a consistent order.
  • The innermost shell has a maximum of two electrons, but the next two electron shells can each have a maximum of eight electrons.
  • This is known as the octet rule which states that, with the exception of the innermost shell, atoms are more stable energetically when they have eight electrons in their valence shell, the outermost electron shell.
  • As shown, helium has a complete outer electron shell, with two electrons filling its first and only shell.

• Classification of Phylum Mollusca

  • Gastropoda includes shell-bearing species as well as species with a reduced shell.
  • These animals are asymmetrical and usually present a coiled shell.
  • Cephalopods are a class of shell-bearing animals as well as mollusks with a reduced shell.
  • These animals bear a single conical shell, which has both ends open .
  • The empty shell of the giant clam, Tridacna gigas.

• Electron Orbitals

  • The second electron shell may contain eight electrons.
  • Larger elements have additional orbitals, making up the third electron shell.
  • Principal shell 3n has s, p, and d subshells and can hold 18 electrons.
  • Principal shell 4n has s, p, d, and f orbitals and can hold 32 electrons.
  • Principal shell 2n has a p subshell, but shell 1 does not.

• Ions and Ionic Bonds

  • This results in a full outermost electron shell and makes them energetically more stable.
  • As illustrated, sodium (Na) only has one electron in its outer electron shell.
  • In this example, sodium will donate its one electron to empty its shell, and chlorine will accept that electron to fill its shell.
  • Both ions now satisfy the octet rule and have complete outer shells.
  • In this example, sodium loses one electron to empty its shell and chlorine accepts that electron to fill its shell.

• Phylum Mollusca

  • They range from large predatory squids and octopus, some of which show a high degree of intelligence, to grazing forms with elaborately-sculpted and colored shells.
  • In spite of their tremendous diversity, however, they also share a few key characteristics, including a muscular foot, a visceral mass containing internal organs, and a mantle that may or may not secrete a shell of calcium carbonate .
  • In shelled mollusks, this foot is usually the same size as the opening of the shell.
  • The mantle (also known as the pallium) is the dorsal epidermis in mollusks; shelled mollusks are specialized to secrete a chitinous and hard calcareous shell.
  • Helix aspersa, a common land snail, has a calcium carbonate shell.

• Rhizaria

  • As a group, the forams exhibit porous shells, called tests, that are built from various organic materials and typically hardened with calcium carbonate.
  • The shells of dead radiolarians sink to the ocean floor, where they may accumulate in 100 meter-thick depths.
  • This fossilized radiolarian shell was imaged using a scanning electron microscope.

• Fossil Formation

  • After a bone, wood fragment, or shell is buried in sediment, it may be exposed to mineral-rich water that moves through the sediment.
  • In some cases, the original bone or shell dissolves away, leaving behind an empty space in the shape of the shell or bone.
  • Many mollusks (bivalves, snails, and squid) are commonly found as molds and casts because their shells dissolve easily .
  • In some cases, the original shell or bone dissolves away and is replaced by a different mineral.
  • For example, shells that were originally calcite may be replaced by dolomite, quartz, or pyrite.

• Characteristics of Reptiles

  • Reptiles are ectothermic tetrapods that lay shelled eggs on land and possess scaly skin and lungs.
  • Reptiles lay on land eggs enclosed in shells.