Mid-year science review

Chemistry, Earth History, Infectious Diseases


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A Periodic Table is a table of chemical elements arranged by order of Atomic Number. It is sorted from left to right, from least reactivity to most.

Contents of a Periodic Table-

Atomic Number: A number which is equal to the number of protons in the nucleus. This helps identify elements. The Atomic Number is located above the element letter.

Protons: A particle within a nucleus which has a positive electrical charge.

Neutrons: A particle within a nucleus which has no electrical charge.

Electrons: A particle which orbits the nucleus which has a negative electrical charge.

Groups: Columns of elements on the periodic table that share common properties.

Periods: Horizontal rows on the periodic table which share common properties.

Law of Conservation of Mass: The principal of the Law of Conservation of Mass states that matter cannot be destroyed nor created, and can only be transferred from state to state.

Elements: Substances which cannot be broken down into a simpler form, All known elements are listed on the Periodic Table.

Compounds: The result of two or more elements combining chemically.

Mixtures: The result of combining two things but them not combining.

Physical/Chemical Properties: Physical properties can be changed or measured without changing what is being studied, Chemical properties can only be observed during a chemical reaction.

Physical/Chemical Change: Physical changed do not form a new substance, while chemical changes change one or more substances into new substances with new properties.


Flammability- The ability of something to catch fire

Reactivity- The amount of reactiveness something has with other elements

Atoms- The basic building blocks of matter

Matter- Everything that exists

Earth History

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The Law of Superposition basically states that any any rock layer is older than the one above it.

Relative Dating: This type of dating is used to find a time era which a fossil is from by comparing that fossil's location/depth with that of other fossils of similar accordance.

Absolute Dating: This type of dating puts an exact date on how many years old a fossil is, which is proven by science at a molecular level, usually found by study of radioactive decay.

Half-Life: The amount of time it takes for half of the molecules of a sample of a once-living organism's fossil to die due to radioactive decay.

Radioactive Dating: Uses Half-Life to determine the amount of time a fossil has been decaying, therefore, roughly, the amount of time the fossil has existed in a nonliving state.

Index Fossils: Usually-common fossils which are used to determine the relative date of other fossils within the same rock layer.

Geologic Time Scale: A time scale of each era of earth's history, used by geologists, paleontologists, and others which study earth history or related fields.

Ice Cores: Ice which is deep within Antarctic ice sheets and holds gas traces and other useful sources of information on the atmosphere of it's time.


Carbon dating- A scientific way of using the elements which are in the fossil or rock surrounding it to help determine the exact age of the fossil.

Isotopes- Different versions of the same elements, Scientists use isotopes for relative dating.

Fossil record- A record of the total number of fossils that have been discovered

Fossil- The trace or remains of an organism which lived long ago.


Igneous- Created from cooled magma

Metamorphic- Created from heat and pressure

Sedimentary- Created from compaction and sedimentation of sediments

Infectious Diseases

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Microorganisms: Organisms which are so small that they usually cannot be seen without a microscope.

  • Virus- An infective agent only able to multiply within a host cell. Nonliving.
  • Bacteria- Tiny microorganisms which can cause disease.
  • Fungi- Microorganisms which can spread by spores and cause diseases like ringworm.
  • Parasite- Can range from a microorganism to a small animal, living organisms which feed off of other living organisms to survive.

Epidemic: A widespread occurrence of a disease within a certain society, country or community at a certain time.

Pandemic: A widespread occurrence of a disease that is spread throughout multiple countries, regions or even continents.

How to prevent: Washing hands, living in clean conditions, eating well prepared food, getting vaccinated.

Biotechnology: The use of organisms to create useful products.