CHEMISTRY - PERIODIC TABLE - ALKALINE EARTH METALS #7

ALKALINE METALS

Heading to Group Two

So we just covered the alkali metals in Group I. You will find the alkaline earth metals right next door in Group II. This is the second most reactivefamily of elements in the periodic table. 
Do you know why they are called alkaline? When these compounds are mixed in solutions, they are likely to form solutions with a pH greater than 7. Those higher pH levels means that they are defined as "basic" or "alkaline" solutions. 

A Family Portrait

Who's in the family? 
The members of the alkaline earth metals include: 

• beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). 

As with all families, these elements share traits. While not as reactive as the alkali metals, this family knows how to make bonds very easily. Each of them has two electrons in their outer shell. They are ready to give up those two electrons in electrovalent/ionic bonds. Sometimes you will see them with two halogen atoms, as with beryllium fluoride (BeF₂), and sometimes they might form a double bond, as with calcium oxide (CaO). It's all about giving up those electrons to have a full outer shell. 

As you get to the bottom of the list, you will find the radioactive radium. While radium is not found around your house anymore, it used to be an ingredient in glow-in-the-dark paints. It was originally mixed with zinc sulfide (ZnS). The other elements are found in many items, including fireworks, batteries, flashbulbs, and special alloys. The lighter alkaline earth metals, such as magnesium and calcium, are very important in animal and plant physiology. You all know that calcium helps build your bones. Magnesium can be found in chlorophyll molecules. 

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CHEMISTRY - ELEMENT OF THE DAY - BERYLLIUM

4

Be

Beryllium

9.012182

Atomic Number: 4

Atomic Weight: 9.012182

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 2    Group Number: 2    

Group Name: Alkaline Earth Metal

What's in a name? From the Greek word beryl, a type of mineral.

Say what? Beryllium is pronounced as beh-RIL-ee-em.

History and Uses:

Although emeralds and beryl were known to ancient civilizations, they were first recognized as the same mineral (Be₃Al₂(SiO₃)₆) by Abbé Haüy in 1798. Later that year, Louis-Nicholas Vauquelin, a French chemist, discovered that an unknown element was present in emeralds and beryl. Attempts to isolate the new element finally succeeded in 1828 when two chemists, Friedrich Wölhler of Germany and A. Bussy of France, independently produced beryllium by reducing beryllium chloride (BeCl₂) with potassium in a platinum crucible. Today, beryllium is primarily obtained from the minerals beryl (Be₃Al₂(SiO₃)₆) and bertrandite (4BeO·2SiO₂·H₂O) through a chemical process or through the electrolysis of a mixture of molten beryllium chloride (BeCl₂) and sodium chloride (NaCl).

Beryllium is relatively transparent to X-rays and is used to make windows for X-ray tubes. When exposed to alpha particles, such as those emitted by radium or polonium, beryllium emits neutrons and is used as a neutron source. Beryllium is also used as a moderator in nuclear reactors.

Beryllium is alloyed with copper (2% beryllium, 98% copper) to form a wear resistant material, known as beryllium bronze, used in gyroscopes and other devices where wear resistance is important. Beryllium is alloyed with nickel (2% beryllium, 98% nickel) to make springs, spot-welding electrodes and non-sparking tools. Other beryllium alloys are used in the windshield, brake disks and other structural components of the space shuttle.

Beryllium oxide (BeO), a compound of beryllium, is used in the nuclear industry and in ceramics.

Beryllium was once known as glucinum, which means sweet, since beryllium and many of its compounds have a sugary taste. Unfortunately for the chemists that discovered this particular property, beryllium and many of its compounds are poisonous and should never be tasted or ingested.

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CHEMISTRY - ELEMENT OF THE DAY - URANIUM

Atomic Number: 92

Phase at Room Temperature: Solid
Element Classification: Metal

Period Number: 7    Group Number: none    Group Name: Actinide

Radioactive

What's in a name? Named for the planet Uranus.

Say what? Uranium is pronounced as you-RAY-nee-em.

You know uranium as a radioactive element, found in bombs, nuclear power plants and hardened metals. It's also found in some decorative glassware, called "vaseline glass", where the uranium compounds contribute a yellowish-green fluorescent color. How much do you know about this element? 

1. Pure uranium is a silvery-white metal.
2. The atomic number of uranium is 92, meaning uranium atoms have 92 protons and usually 92 electrons. The isotope of uranium depends on how meany neutrons it has.
3. Because uranium is radioactive and always decaying, radium is always found with uranium ores.
4. Uranium is slightly paramagnetic.
5. Uranium is named for the planet Uranus.
6. Uranium is used to fuel nuclear power plants and in high-density penetrating ammunition. A single kilogram of uranium-235 theoretically could produce ~80 terajoules of energy, which is equivalent to the energy that could be produced by 3000 tonnes of coal.
7. Natural uranium ore has been known to fission spontaneously. The Oklo Fossil Reactors of Gabon, West Africa, contain 15 ancient inactive natural nuclear fission reactors. The natural ore fissioned back at a prehistoric time when 3% of the natural uranium existed as uranium-235, which was a high enough percentage to support a sustained nuclear fission chain reaction.
8. The density of uranium is about 70% higher than lead, but less than that of gold or tungsten, even though uranium has the second-highest atomic weight of the naturally occurring elements (second to plutonium-244).
9. Uranium usually has a valence of either 4 or 6.
10. Health effects of uranium typically are not related to the element's radioactivity, since the alpha particles emitted by uranium cannot even penetrate skin. Rather, the health impact is related to the toxicity of uranium and its compounds. Ingestion of hexavalent uranium compounds can cause birth defects and immune system damage.
11. Finely divided uranium powder is pyrophoric, meaning it will ignite spontaneously at room temperature.

CHEMISTRY - ELEMENT OF THE DAY - LITHIUM

3

Li

Lithium

6.941

Atomic Number: 3

Atomic Weight: 6.941

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 2    Group Number: 1    

Group Name: Alkali Metal

What's in a name? From the Greek word for stone, lithos.

Say what? Lithium is pronounced as LITH-ee-em.

History and Uses:

Lithium was discovered in the mineral petalite (LiAl(Si₂O₅)₂) by Johann August Arfvedson in 1817. It was first isolated by William Thomas Brande and Sir Humphrey Davy through the electrolysis of lithium oxide (Li₂O). Today, larger amounts of the metal are obtained through the electrolysis of lithium chloride (LiCl). Lithium is not found free in nature and makes up only 0.0007% of the earth's crust.

Many uses have been found for lithium and its compounds. Lithium has the highest specific heat of any solid element and is used in heat transfer applications. It is used to make special glasses and ceramics, including the Mount Palomar telescope's 200 inch mirror. Lithium is the lightest known metal and can be alloyed with aluminium, copper, manganese, and cadmium to make strong, lightweight metals for aircraft. Lithium hydroxide (LiOH) is used to remove carbon dioxide from the atmosphere of spacecraft. Lithium stearate (LiC₁₈H₃₅O₂) is used as a general purpose and high temperature lubricant. Lithium carbonate (Li₂CO₃) is used as a drug to treat manic depression disorder.

CHEMISTRY - PERIODIC TABLE - ALKALI METALS #6

ALKALI METALS

Alkali Metals to the Left

Let's go to the left side of the periodic table. When looking for families, the first one you will find is the alkali metal family of elements. They are also known as the alkaline metals. 
You should remember that there is a separate group called the alkaline earth metals in Group Two. They are a very different family, even though they have a similar name. That far left column is Group One (Group I). When we talk about the groups of the periodic table, scientists use Roman numerals when they write them out. The "one" in this case refers to having one electron in the outermost orbital. 

A Family Portrait

Who's in the family? Starting at the top we find hydrogen (H). But wait. That element is NOT in the family. When we told you about families, we said that they were groups of elements that react in similar ways. Hydrogen is a very special element of the periodic table and doesn't belong to any family. While hydrogen sits in Group I, it is NOT an alkali metal. 

Family Bonding

Now that we've covered that exception, the members of the family include:

• lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr). As with all families, these elements share traits. They are very reactive. Why? They all have one electrons in their outer shell. That's one electron away from being happy (full shells). When you are that close to having a full shell, you want to bond with other elements and lose that electron. An increased desire to bond means you are more reactive. In fact, when you put some of these pure elements in water (H₂O), they can cause huge explosions. 

• The alkali metals are also metals. That seems obvious from the name. Often, in chemistry, characteristics are assigned by the way elements look. 
• You will find that the alkali group is shiny and light in weight. Their light weight and physical properties separate them from other metals. 
• They are malleable (bendable) and sometimes soft enough to be cut with a dull knife. 
• Alkali metals are not the type of metals you would use for coins or houses. 

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CHEMISTRY - PERIODIC TABLE - METALS #5

Metal Basics

We wanted to give you a big overview of metals before we get into details about specific families. 
Almost 75% of all elements are classified as metals. 

They are not all like silver (Ag), gold (Au), or platinum (Pt). Those are the very cool and shiny ones. There are other metals like potassium (K) and iridium (Ir) that you might not think about right away. 

Many Kinds of Metals

How many kinds of metals are there? So many. Don't even try to memorize them all. Just remember the ones you might need in class. 
Here's a quick list: 

• Actinide Metals, Lanthanide Metals, Alkali Metals, Alkaline-Earth Metals, Rare Metals, Rare-Earth Metals, and Transition Metals. 
• Remember, that's the easy list. Lucky for you, the periodic table is excellent at organizing elements, and you will find each of these groups in specific areas of the periodic table. 

How Do You Identify a Metal?

What are the characteristics of metals? We've got four traits that will help you identify whether an element is a metal or not: 

1. Conduction: Metals are good at conducting electricity. Silver (Ag) and copper (Cu) are some of the most efficient metals and are often used in electronics. 

2. Reactivity: Metals are very reactive, some more than others, but most form compounds with other elements quite easily. Sodium (Na) and potassium (K) are some of the most reactive metals. A metal like iron (Fe) forms iron oxide (Fe₂O₃), which you know as rust. 

3. Chemical: It gets a little complex here. Metals usually make positive ions when the compounds are dissolved in solution. Also, their metallic oxides make hydroxides (bases) (OH^-), and not acids, when in solution. Think about this example: When sodium chloride (NaCl) is dissolved in water (H₂O), it breaks apart into sodium (Na+) and chlorine (Cl^-) ions. Do you see how that sodium is the positive ion? Sodium is the metal. It works that way for other metals. Potassium chlorine (KCl) works the same way. When it is dissolved, the potassium ion (K⁺) is the positive ion. 

4. Alloys: Metals are easily combined. Mixtures of many metallic elements are called alloys. Examples of alloys are steel and bronze. 

CHEMISTRY -PERIODIC TABLE - NOBLE GASES #4

The Noble Gases

We love the noble gases. Some scientists used to call them the inert gases. It didn't really work because there are a few other gases that are basically inert but not noble gases.
Nitrogen (N₂) might be considered an inert gas, but it is not a noble gas. 

The noble gases are another family of elements, and all of them are located in the far right column of the periodic table. For all of you budding chemists, the far right is also known as Group Zero (Group 0) or Group Eighteen (Group XVIII). This family has the happiest elements of all. 

Why Are They Happy?

Using the Bohr description of electron shells, happy atoms have full shells. All of the noble gases have full outer shells with eight electrons. 
Oh, wait! That's not totally correct. At the top of the noble gases is little helium (He), with a shell that is full with only two electrons. The fact that their outer shells are full means they are quite happy and don't need to react with other elements. In fact, they rarely combine with other elements. That non-reactivity is why they are called inert. 

Who's in the Family?

All of the elements in Group Zero are noble gases. The list includes helium, neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Don't think that, because these elements don't like to react, we don't use them. You will find noble gases all over our world. Neon is used in advertising signs. Argon is used in light bulbs. Helium is used in balloons and to cool things. Xenon is used in headlights for new cars. Because of their chemical properties, these gases are also used in the laboratory to help stabilize reactions that would usually proceed too quickly. When you move down the periodic table, as the atomic numbers increase, the elements become rarer. They are not just rare in nature, but rare as useful elements, too. 

But Wait, They Do Bond!

Some do. As of about 40 years ago, scientists have been able to make some compounds with noble gases. Some have been used in compounds to make explosives, and others just form compounds in a lab. The thing to remember is that they were forced. When going about their natural lives, you will never (well, never say never, because there may be an exception) find the noble gases bonded to other elements. 

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CHEMISTRY - ELEMENT OF THE DAY - ARGON

18

Ar

Argon

39.948

Atomic Number: 18

Atomic Weight: 39.948

Phase at Room Temperature: Gas

Element Classification: Non-metal

Period Number: 3    Group Number: 18    

Group Name: Noble Gas

What's in a name? From the Greek word for inactive, argos.

Say what? Argon is pronounced as AR-gon.

History and Uses:

Argon was discovered by Sir William Ramsay, a Scottish chemist, and Lord Rayleigh, an English chemist, in 1894. Argon makes up 0.93% of the earth's atmosphere, making it the third most abundant gas. Argon is obtained from the air as a byproduct of the production of oxygen and nitrogen.

Argon is frequently used when an inert atmosphere is needed. It is used to fill incandescent and fluorescent light bulbs to prevent oxygen from corroding the hot filament. Argon is also used to form inert atmospheres for arc welding, growing semiconductor crystals and processes that require shielding from other atmospheric gases.

Once thought to be completely inert, argon is known to form at least one compound. The synthesis of argon fluorohydride (HArF) was reported by Leonid Khriachtchev, Mika Pettersson, Nino Runeberg, Jan Lundell and Markku Räsänen in August of 2000. Stable only at very low temperatures, argon fluorohydride begins to decompose once it warms above -246°C (-411°F). Because of this limitation, argon fluorohydride has no uses outside of basic scientific research.

CHEMISTRY - PERIODIC TABLE - HALOGENS #3

Halogens on the Right

In the second column from the right side of the periodic table, you will find Group Seventeen (Group XVII). 

This column is the home of theHalogen family of elements. 

Who is in this family? The elements included are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). 

What Makes Them Similar?

When you look at our descriptions of the elements fluorine and chlorine, you will see that they both have seven electrons in their outer shell. That seven-electron trait applies to all of the halogens. They are all just one electron shy of having full shells. Because they are so close to being happy, they have the trait of combining with many different elements. They are very reactive. You will often find them bonding with metals and elements from Group One of the periodic table. The elements in the column on the left each have one electron that they like to donate. 

We've just told you how reactive the halogens are. Not all halogens react with the same intensity or enthusiasm. Fluorine is the most reactive and combines with most elements from around the periodic table. Reactivity decreases as you move down the column. As you learn more about the table, you will find this pattern true for other families. As the atomic number increases, the atoms get bigger. Their chemical properties change just a little bit when compared to the element right above them on the table. 

What is a Halide?

The elements we are talking about in this section are called halogens. When a halogen combines with another element, the resulting compound is called a halide. One of the best examples of a halide is sodium chloride (NaCl). Don't think that the halogens always make ionic compounds and salts. Some halides of the world are a part of molecules with covalent bonds. 

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QUIZ - HALOGENS