Mid Year Science Review

Chemistry, Earth History, Infectious Diseases

Groups and Periods

  1. Periods- Seven periods of elements occur naturally on Earth. A horizontal row of elements in the periodoic table
  2. Groups- Elements in the same vertical column of the periodic table.
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• Elements, Compounds, Mixtures

Elements-A pure substance that cannot be broken down into other substances by chemical or physical means.

Compounds- A pure substance made of two or more elements chemically combined.

Mixtures- Two or more substances that are mixed together but not chemically combined.

• Physical/ Chemical Properties

physical- A physical property is any property that is measurable whose value describes a state of a physical system

Chemical- a property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed:

physical and chemical changes

physical - a usually reversible change in the physical properties of a substance.

chemical- a usually irreversible chemical reaction involving the rearrangement of the atoms of one or more substances and a change in their chemical.

Earth History

law of superposition

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• Relative/Absolute Dating

relative- radiometric dating which provided a means of absolute dating in the early 20th century.

absolute- Absolute dating is the process of determining an approximate computed age in archaeology and geology.

• Half-life/Radioactive Dating

radioactive- A process for determining the age of an object by measuring the amount of a given radioactive material it contains.

half life- half-life is radiocarbon dating, where an object's age can be determined very precisely based on the amount of carbon-14 (a radioactive isotope) contained in the object relative to carbon-12 (a stable isotope).

• Index Fossils

  1. A fossil that is useful for dating and correlating the strata in which it is found.

• Geologic Time Scale

The geologic time scale (GTS) is a system of chronological measurement that relates stratigraphy to time.

• Ice Cores

  1. An ice core is a core sample that is typically removed from an icesheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere.

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