Compare and contrast

Compare and contrast are multi-paragraph compositions that explain ways in which two (or, very occasionally, more) subjects are similar or different.

In these article, compare means describing similarities between the subjects. When we are comparing Lithium and Calcium.

Lithium

Lithium (Li) is a silvery gray metal with an atomic number of three. While being the lightest metal under normal conditions, it is still the most dense. With an atomic number of three, lithium has three protons in the nucleus, but like many other alkalai metals it has only one valence electron.

Interesting Lithium Facts:

·         It is the least reactive of the alkalai metals.

·         The nucleus of lithium is fairly unstable.

·         Because of this instability, lithium alone almost never appears in nature.

·         While it appears metallic and shiny, it begins to corrode immediately in air due to the moisture present.

·         It is a metal, but soft enough to be cut with a knife.

·         The first man-made nuclear reaction took place in 1932 when lithium was converted into helium through transmutation.

·         Lithium is used in producing glass and ceramics, but most well-known for batteries.

·         Because of its great strength in small amounts, it is used in common alloys.

·         All organisms contain lithium in small amounts, but does not seem to serve a biological purpose.

·         Lithium ions are used in creating mood-altering medications for the treatment of bipolar disorder.

·         Lithium has two stable isotopes in nature, one of which has a 92.5% abundance.

·         According to theory, lithium is one of three elements believed to have been created during the Big Bang.

·         Lithium is very abundant in sea water and if often mined from brines and clay.

·         Lithium salts burn with a bright red flame.

·         The current availability of lithium is a deciding factor in the creation of larger batteries for electric car production.

·         Lithium has become carefully guarded since it is a key ingredient in the production of methamphetamine.

Calcium

Calcium (Ca) is a gray, soft alkaline earth metal with an atomic number of twenty. It is a vital element for living organisms.

Interesting Calcium Facts:

·         Calcium is the fifth most plentiful element in the Earth's crust.

·         It is also the fifth most abundant element found dissolved in the oceans.

·         Calcium has been in use for over 16,000 years, but was formally isolated in 1808 by Sir Humphry Davy.

·         It is not found in its natural state, but is found commonly in minerals and in its compounds.

·         There are fifteen recognized compounds for calcium, all with unique industrial uses.

·         Calcium is used in the creation of hydrogen, as it reacts with water to give off the gas.

·         Calcium is slow to react in water because it is coated in an insoluble calicum hydroxide.

·         Calcium is the lightest of the alkaline earth metals with a density of 1.55 g/cm3.

·         There are two allotropes of of calcium.

·         Calcium is the fifth more prevalent element in the human body.

·         It has many functions in the body, but mostly it is used to provide support for the skeleton.

·         There is approximately one kilogram of calcium in an average-sized human skeleton.

·         Calcium's high atomic number is what allows human bones to show up under Xray.

·         Calcium joins with phosphate to form hydroyxlapatite, the main component in bones and tooth enamel.

·         Calcium has four stable isotopes and two unstable isotopes.

·         The half-lives of the unstable calcium isotopes are so long that they may be considered almost stable.

·         Ca-41 decays to an isotope of potassium, and scientists use this decay as an indication of anomalies in solar systems.

·         Calcium and most of its compounds are fairly low in toxicity.

·         Calcium has very few environmental dangers.

·         When consumed in excess, however, calcium overdose can lead to kidney failure.

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