periodic table

Examples of periodic table in the following topics:

• The Periodic Table

  • The periodic table is a means of organizing the various elements according to similar physical and chemical properties.
  • The different elements are organized and displayed in the periodic table.
  • The arrangement of the periodic table allows the elements to be grouped according to their chemical properties.
  • Today, the periodic table continues to expand as heavier and heavier elements are synthesized in laboratories.
  • The periodic table shows the atomic mass and atomic number of each element.

• Electron Orbitals

  • On the periodic table, hydrogen and helium are the only two elements in the first row (period); this is because they are the sole elements to have electrons only in their first shell, the 1s orbital.
  • Progressing from one atom to the next in the periodic table, the electron structure can be worked out by fitting an extra electron into the next available orbital.

• Electron Shells and the Bohr Model

  • The periodic table is arranged in columns and rows based on the number of electrons and where these electrons are located, providing a tool to understand how electrons are distributed in the outer shell of an atom.
  • Thus, the columns of the periodic table represent the potential shared state of these elements' outer electron shells that is responsible for their similar chemical characteristics.

• Biodiversity Change through Geological Time

  • Biodiversity has been affected by five mass extinction periods, which greatly influenced speciation and extinction rates.
  • The fossil record of the mass extinctions was the basis for defining periods of geological history, so they typically occur at the transition point between geological periods.
  • The main hypothesis for its cause was a period of glaciation followed by warming.
  • The late Devonian extinction may have occurred over a relatively long period of time.
  • The table shows the time that elapsed between each period.

• The Study of Population Dynamics

  • These demographic characteristics are often displayed in the form of a life table.
  • The tables are modeled after actuarial tables used by the insurance industry for estimating human life expectancy.
  • Life tables may include:
  • Very few individuals survive the younger years; however, those that live to old age are likely to survive for a relatively-long period.
  • Distinguish between life tables and survivorship curves as used in demography

• Transport of Electrolytes across Cell Membranes

  • A teaspoon of table salt readily dissolves in water.
  • For this reason, athletes are encouraged to replace electrolytes and fluids during periods of increased activity and perspiration.

• Pre-Cambrian Animal Life

  • Early animal life (Ediacaran biota) evolved from protists during the pre-Cambrian period, which is also known as the Ediacaran period.
  • The time before the Cambrian period is known as the Ediacaran period (between 635-543 million years ago), the final period of the late Proterozoic Neoproterozoic Era .
  • Fossils of (a) Cyclomedusa and (b) Dickinsonia that evolved during the Ediacaran period.
  • (a) Earth's history is divided into eons, eras, and periods.
  • The Ediacaran period was the final period of the Proterozoic Era which ended in the Cambrian period of the Phanerozoic Era.

• The Cambrian Explosion of Animal Life

  • Echinoderms, mollusks, worms, arthropods, and chordates arose during this period.
  • Unresolved questions about the animal diversification that took place during the Cambrian period remain.
  • For example, we do not understand how the evolution of so many species occurred in such a short period of time.
  • Furthermore, the vast diversification of animal species that appears to have begun during the Cambrian period continued well into the following Ordovician period.
  • These fossils (a–d) belong to trilobites, extinct arthropods that appeared in the early Cambrian period 525 million years ago and disappeared from the fossil record during a mass extinction at the end of the Permian period about 250 million years ago.

• Water’s Solvent Properties

  • 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.

• Evolution of Gymnosperms

  • Seed ferns gave rise to the gymnosperms during the Devonian Period, allowing them to adapt to dry conditions.
  • Seed plants resembling modern tree ferns became more numerous and diverse in the coal swamps of the Carboniferous period.
  • Following the wet Mississippian and Pennsylvanian periods, which were dominated by giant fern trees, the Permian period was dry.
  • The Jurassic period was as much the age of the cycads (palm-tree-like gymnosperms) as the age of the dinosaurs.
  • Explain how and why gymnosperms became the dominant plant group during the Permian period