Alkaline
Earth MetalsAlkaline
Earth Metals
Beryllium #4 Be
Magnesium #12 Mg
Calcium #20 Ca
Strontium #38 Sr
Barium #56 Ba
Radium #88 Ra
Alkaline Earth Metals are softer than most other metals, and react readily with water (especially when heated) but not as much as the corresponding alkali metals. They are therefore like milder versions of the alkali metals. Like the alkali metals, they are stored in petroleum products to keep them from reacting with air or water.
Focus on calcium and magnesium, the most important and common alkaline earth metals. Think of them as the limestone metals, if you like. Or the Rolaids metals. Limestone and dolomite, common rocks all over the Earth (hint, hint - "alkaline EARTH metals"), are composed of calcium and magnesium carbonates. So is Rolaids and Tums, common antacids.
"Earth metals" comes from alchemy, which was used to describe metals that resisted fire -- the oxides of the alkaline earth metals are not affected by fire.
TIP: MgC03 and CaC03 (carbonates) form a large percentage of rock on the earth's crust: including the common rocks of limestone, dolomite, calcite, marble and chalk. Therefore, when you think of calcium and magnesium, think "earth" and then "earth metals".
Calcium and magnesium carbonates are the primary ingredients of antacids like Rolaids and Tums. "Milk of Magnesia" is an old antacid made of MgOH- (magnesium hydroxide). These compounds are used as antacids because they are alkaline (high pH), hence calcium and magnesium are known as alkaline earth metals.
Be, Beryllium (atomic number 4), page 29.
The name Beryllium comes from the Greek beryllos which is the name for the gemstone beryl. The element is a high-melting, silver-white metal which is the first member of the alkaline earth metals. It is not abundant in the environment and occurs mainly in the mineral beryl with aluminum and silicon.
Beryllium was first isolated in 1828 by Wohler. It is used in specialty alloys such as spring metal in which it increases toughness. It was once known as glucinium because of the sweet taste of its compounds (which, alas, are toxic).
The chief mineral source of beryllium is also the same material of which emeralds are formed. High quality beryl crystals with chromium impurities have an exquisite green color which has been valued for thousands of years.
Additional Information About Beryllium
Mg, Magnesium (atomic number 12, page 57 in book, symbol Mg)
Warning: don't confuse Magnesium (Mg) with Manganese (Mn).
Magnesium takes it name from magnesite ore, named for the district Magnesia in Thessaly, Greece. (That's where they must have got the name for "Milk of Magnesia".
Magnesium Carbonate forms the mineral and rock called dolomite. Dolomite is often used to "lime" lawns (make them less acidic).
It is a silver-white metal which burns in air with a blinding white light. It reacts with hot water and acids. The metal is widely distributed in the environment in a number of minerals and a significant amount is found in sea water.
The metal and its alloys are widely used to manufacture light-weight mechanical parts.
Magnesium is also an important nutritional element in trace amounts and is the central atom in the complex chlorophyll molecule.
Questions:
1. The most important process of obtaining magnesium involves the extraction of magnesium from what? seawater.
2. Magnesium is an important structural material, especially when added to metal alloys, because it is strong but very what? light (even lighter than aluminum).
3. When water contains too much calcium or magnesium, it is said to be what? hard water (which needs a water softener to prevent scale from building up).
4. These salts are a hydrated form of magnesium sulfate and are used in baths for medicinal purposes. Epsom salts.
5. True or false: Magnesium compounds are used as antacids? true (Rolaids and Milk of Magnesia).
6. Magnesium carbonate (MgC03), a rock once called "Magnesite", is now called what? dolomite (almost the same as limestone and often mixed with limestone. When metamorphosed it can turn into marble, just like limestone)
7. What is the chemical symbol for magnesium? Mg (NOT Mn!)
Calcium (atomic Number 20), page 75, chemical symbol Ca
***This is the most important and most common of the alkaline earth metals.
Calcium is a silver-gray metal which takes its name from the Latin word calx, which means lime. It is the fifth most abundant element in the earth's crust and is widely distributed as limestone (remember earth metal!).
Calcium carbonate (CaCO3) crystalizes into the mineral calcite, the main components of limestone and marble.
Hydrated calcium sulfate makes gypsum (varieties include alabaster, satin spar, desert rose, etc). When gypsum is dehydrated, it makes Plaster of Paris and "sheet-rock" or "wall-board".
Calcium compounds are used in the manufacture of iron and steel, cements and plasters, as well as gypsum wall board. It is important biologically in the formation of bones and teeth.
You know calcium is quite reactive, because it is an alkaline earth metal, right?
Questions:
1. True or false: Calcium is the fourth most abundant element in the Earth's crust. False (it is the fifth most abundant)
2. The Romans used a calcium oxide compound called "calx", which they made heating limestone. What do we call that compound today? lime
3. What is the most important use of lime today? in smelting iron (the lime combines with impurities to form an easily separated slag.)
4. Calcium carbonate, the active ingredient in many antacids, crystallizes to form what mineral? calcite (also aragonite, depending on temperature and pressure)
5. Massive calcite deposits are called what type of common rock? limestone (including limestone varieties like stalactites and chalk).
6. Forms of calcium carbonate, such as limestone, calcite, Rolaids, or marble vases, will fizz in what type of acid? hydrochloric acid (aka muriatic acid).
7. Marble is very sensitive to what type of rain? Acid rain.
8. Gypsum, a mineral and rock made of hydrated calcium sulfate, is used in housing construction as what? wall-board (sheet rock)
9. Before wall-board was invented, walls were coated with layers of this gypsum-based substance. Plaster of Paris.
Sr, Strontium (atomic number 38) page 113,
The element strontium is named for a Scottish town, Strontian.
Strontium compounds are useful in pyrotechnic devices and signal flares because of the bright crimson coloring they give to flames.
Strontium-90, a radioactive isotope of the metal produced by fission reactions is a dangerous environmental menace because its chemistry is similar to calcium and it may take its place in bones. The strong radiation emitted by the isotope interferes with the production of new blood cells and can cause death.
Questions:
1. The half-life of strontium is about how many years? 28.8 (if you say 30 that is close enough).
2. Radioactive strontium, a byproduct of nuclear reactions, can take the same place as what other alkaline earth metal in your body? calcium
Ba, Barium (atomic number 56, page 144) takes it name from the Greek word barys for heavy. It was first isolated in 1808 by Davy and is a soft silver-white metal.
Like the lighter members of its family, barium reacts vigorously with water to produce hydrogen gas and so is commonly stored in oil.
The metal does not occur free in nature but chiefly as the sulfate and carbonate. The sulfate is used in X-ray diagnostics as a contrast medium (i.e., in soft tissue like the digestive tract).
Barium compounds (which are toxic) are also useful in pyrotechnic devices where they impart a characteristic green color.
Questions:
1. Barium sulfate, when ingested, hilites a person's intestines on what type of medical picture? xray
Radium (atomic number 88) takes its name from the Latin word radius or ray. All isotopes of radium are radioactive and many exhibit luminescence, reacting readily with oxygen and water. The metal was discovered and isolated in 1911 by Marie Curie.
When first discovered, compounds of the metal were used on watch dials for self-luminescence and in early cancer therapy. It has been all but replaced now by safer alternatives.
Questions:
Which Alkaline Earth Metal(s)....
1. Is the most common and most important? calcium
2. Is used in metal alloys because it is strong and very light? magnesium
3. Are commonly used as antacids? calcium and magnesium
4. Is found in the mineral calcite? calcium
5. Is found in wall-board? calcium
6. Is used in taking x-rays of the digestive tract? barium
7. Is found in gypsum? calcium
8. Makes teeth strong? calcium
9. Is found in the mineral and rock called dolomite? magnesium
10. Is always radioactive? Radium
11. One of its isotopes is a byproduct of nuclear reactions and has a half life of about 30 years. Strontium
12. Came from a substance originally known by the Romans as "calx". Calcium
13. Is used in concrete. calcium