HAPPY HALLOWEEN

CHEMISTRY - DANGER MODULE #11

Dangerous Particles

Radioactivity occurs when an atomic nucleus breaks down into smaller particles. There are three types of particles: alpha, beta, and gamma. Alpha particles are positively charged, beta particles are negatively charged, and gamma particles have no charge. The particles also have increasing levels of energy. Alpha has the lowest energy, beta has a bit more, and then gamma is the fastest and most energetic of all the emission particles. 

The term half-life describes the time it takes for the amount of radioactivity to go down by one-half. Let's say you have some uranium (U) (don't try this at home!) and it's radioactive. When your measurements tell you that the level of radioactivity has gone down by one-half, the amount of time that has passed is the half-life. Every isotope has its own unique half-life. The half-life of uranium-235 is 713,000,000 years. The half-life of uranium-238 is 4,500,000,000 years. That's a long time to wait for the radioactivity to decrease. 

Harnessing the Energy

Nuclear energy is the energy released when the nuclei (nuclei is the plural of nucleus) of atoms split or are fused. You know the nucleus is made up of protons and neutrons. Nuclear forces hold all of the pieces together. Fusion is when two nuclei come together. Fission is when one nucleus is split into two or more parts. Huge amounts of energy are released when either of these reactions occurs. Fusion reactions create much of the energy given off by the Sun. Fission creates the much smaller particles that make up the protons and neutrons that physicists are studying every day. In our nuclear reactors, fission is the main process. In the Sun, fusion is the big process. 

Atoms from the Mirror Universe

Since we're talking a little bit about atomic and nuclear physics, we wanted to tell you about antimatter. It's not just found in television shows. Scientists have proved that it is real. While a regular atom has positive and neutral pieces (protons/neutrons) in the nucleus and negative pieces in orbiting clouds (electrons), antimatter is just the opposite. Antimatter has a nucleus with a negative charge and little positive pieces in the orbits. Those positively charged pieces are called positrons. According to news reports in 2010, scientists at CERN (a particle collider) created antihydrogen atoms. They couldn't really do anything with them, since they lasted for less than a second... but they made them! 

CHEMISTRY - ELEMENT OF THE DAY - SULFUR

16

S

Sulfur

32.065

Atomic Number: 16

Atomic Weight: 32.065

Phase at Room Temperature: Solid

Element Classification: Non-metal

Period Number: 3    Group Number: 16   

Group Name: Chalcogen

What's in a name? From the Sanskrit word sulvere and the Latin word sulphurium.

Say what? Sulfur is pronounced as SUL-fer.

History and Uses:

Sulfur, the tenth most abundant element in the universe, has been known since ancient times. Sometime around 1777, Antoine Lavoisier convinced the rest of the scientific community that sulfur was an element. Sulfur is a component of many common minerals, such as galena (PbS), gypsum (CaSO₄·2(H₂O), pyrite (FeS₂), sphalerite (ZnS or FeS), cinnabar (HgS), stibnite (Sb₂S₃), epsomite (MgSO₄·7(H₂O)), celestite (SrSO₄) and barite (BaSO₄). Nearly 25% of the sulfur produced today is recovered from petroleum refining operations and as a byproduct of extracting other materials from sulfur containing ores. The majority of the sulfur produced today is obtained from underground deposits, usually found in conjunction with salt deposits, with a process known as the Frasch process.

Sulfur is a pale yellow, odorless and brittle material. It displays three allotropic forms: orthorhombic, monoclinic and amorphous. The orthorhombic form is the most stable form of sulfur. Monoclinic sulfur exists between the temperatures of 96°C and 119°C and reverts back to the orthorhombic form when cooled. Amorphous sulfur is formed when molten sulfur is quickly cooled. Amorphous sulfur is soft and elastic and eventually reverts back to the orthorhombic form.

Most of the sulfur that is produced is used in the manufacture of sulfuric acid (H₂SO₄). Large amounts of sulfuric acid, nearly 40 million tons, are used each year to make fertilizers, lead-acid batteries, and in many industrial processes. Smaller amounts of sulfur are used to vulcanize natural rubbers, as an insecticide (the Greek poet Homer mentioned "pest-averting sulphur" nearly 2,800 years ago!), in the manufacture of gunpowder and as a dying agent.

In addition to sulfuric acid, sulfur forms other interesting compounds. Hydrogen sulfide (H₂S) is a gas that smells like rotten eggs. Sulfur dioxide (SO₂), formed by burning sulfur in air, is used as a bleaching agent, solvent, disinfectant and as a refrigerant. When combined with water (H₂O), sulfur dioxide forms sulfurous acid (H₂SO₃), a weak acid that is a major component of acid rain.

SCIENCE NEWS - When to Catch a Lie via Text # 22

You’re texting with a friend. The back and forth is fast and furious. Until…there’s an awkwardly long pause. You might think, aw, they just got another call, or had to get back to their dinner, whatever. But maybe…they’re about to lie.
At least that was one conclusion from an experiment published in a journal called ACM Transactions on Management Information Systems.
Scientists had 100 participants converse via online text with a specially developed computer program. The computer asked each participant 30 questions. And the participants were instructed to lie in half the responses. The researchers found that the lies took 10 percent longer to write, were shorter and were edited more than the truthful messages. 
How can you tell if someone is heavily editing a text? Newer smartphones let you know when the other person is typing. A lot of starting and stopping could mean the texter is carefully constructing a response that might not hold up in a court of law.
Bottom line: dishonest texts take longer on average to write—but it’s also possible your friend may be making an honest attempt to fix those pesky incorrect auto-corrects.
—Christie Nicholson

CHEMISTRY - ELEMENT OF THE DAY - PHOSPHORUS

15

P

Phosphorus

30.973762

Atomic Number: 15

Atomic Weight: 30.973762

Phase at Room Temperature: Solid

Element Classification: Non-metal

Period Number: 3    Group Number: 15    

Group Name: Pnictogen

What's in a name? From the Greek word for light bearing, phosphoros.

Say what? Phosphorus is pronounced as FOS-fer-es.

History and Uses:

In what is perhaps the most disgusting method of discovering an element, phosphorus was first isolated in 1669 by Hennig Brand, a German physician and alchemist, by boiling, filtering and otherwise processing as many as 60 buckets of urine. Thankfully, phosphorus is now primarily obtained from phosphate rock (Ca₃(PO₄)₂).

Phosphorus has three main allotropes: white, red and black. White phosphorus is poisonous and can spontaneously ignite when it comes in contact with air. For this reason, white phosphorus must be stored under water and is usually used to produce phosphorus compounds. Red phosphorus is formed by heating white phosphorus to 250°C (482°F) or by exposing white phosphorus to sunlight. Red phosphorus is not poisonous and is not as dangerous as white phosphorus, although frictional heating is enough to change it back to white phosphorus. Red phosphorus is used in safety matches, fireworks, smoke bombs and pesticides. Black phosphorus is also formed by heating white phosphorus, but a mercury catalyst and a seed crystal of black phosphorus are required. Black phosphorus is the least reactive form of phosphorus and has no significant commercial uses.

Phosphoric acid (H₃PO₄) is used in soft drinks and to create many phosphate compounds, such as triple superphosphate fertilizer (Ca(H₂PO₄)₂·H₂O). Trisodium phosphate (Na₃PO₄) is used as a cleaning agent and as a water softener. Calcium phosphate (Ca₃(PO₄)₂) is used to make china and in the production of baking powder. Some phosphorus compounds glow in the dark or emit light in response to absorbing radiation and are used in fluorescent light bulbs and television sets.

SCIENCE NEWS - Protect Infants from Whooping Cough by Vaccinating Older Kids # 21

Whooping cough, also called pertussis, can cause fatal respiratory failure in infants. Now a study finds that one way to help protect the very young from this disease is vaccination—of kids a few years older than the babies.  
The recent resurgence of pertussis led to a 2006 recommendation by the Centers for Disease Control and Prevention that adolescents be vaccinated. The current study used pre-2006 data to estimate the number of babies who would have been hospitalized for pertussis had the vaccination effort not occurred.
Researchers found that the actual number of infants hospitalized in the years since the adolescent immunization program started was far lower than what would have been forecast.
For example, in 2011 adolescent vaccination led to a greater than 70 percent reduction in infant hospital cases. Credit goes to so-called herd immunity: protected people means more dead ends for an infection trying to spread. The work is in the journal Pediatrics. [Katherine A. Auger, Stephen W. Patrick and Matthew M. Davis, Infant Hospitalizations for Pertussis Before and After Tdap Recommendations for Adolescents]
Sadly, a thousand babies still got sick. Vaccinations for people of all ages will help smother pertussis in the crib.
—Sophie Bushwick

CHEMISTRY - ELEMENT OF THE DAY - ALUMINUM

13

Al

Aluminum

26.9815386

Atomic Number: 13

Atomic Weight: 26.9815386

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 3    Group Number: 13    

Group Name: none

What's in a name? From the Latin word for alum, alumen.

Say what? Aluminum is pronounced as ah-LOO-men-em.

History and Uses:

Although aluminum is the most abundant metal in the earth's crust, it is never found free in nature. All of the earth's aluminum has combined with other elements to form compounds. Two of the most common compounds are alum, such as potassium aluminum sulfate (KAl(SO₄)₂·12H₂O), and aluminum oxide (Al₂O₃). About 8.2% of the earth's crust is composed of aluminum.

Scientists suspected than an unknown metal existed in alum as early as 1787, but they did not have a way to extract it until 1825. Hans Christian Oersted, a Danish chemist, was the first to produce tiny amounts of aluminum. Two years later, Friedrich Wöhler, a German chemist, developed a different way to obtain aluminum. By 1845, he was able to produce samples large enough to determine some of aluminum's basic properties. Wöhler's method was improved in 1854 by Henri Étienne Sainte-Claire Deville, a French chemist. Deville's process allowed for the commercial production of aluminum. As a result, the price of aluminum dropped from around $1200 per kilogram in 1852 to around $40 per kilogram in 1859. Unfortunately, aluminum remained too expensive to be widely used.

Two important developments in the 1880s greatly increased the availability of aluminum. The first was the invention of a new process for obtaining aluminum from aluminum oxide. Charles Martin Hall, an American chemist, and Paul L. T. Héroult, a French chemist, each invented this process independently in 1886. The second was the invention of a new process that could cheaply obtain aluminum oxide from bauxite. Bauxite is an ore that contains a large amount of aluminum hydroxide (Al₂O₃·3H₂O), along with other compounds. Karl Joseph Bayer, an Austrian chemist, developed this process in 1888. The Hall-Héroult and Bayer processes are still used today to produce nearly all of the world's aluminum.

With an easy way to extract aluminum from aluminum oxide and an easy way to extract large amounts of aluminum oxide from bauxite, the era of inexpensive aluminum had begun. In 1888, Hall formed the Pittsburgh Reduction Company, which is now known as the Aluminum Company of America, or Alcoa. When it opened, his company could produce about 25 kilograms of aluminum a day. By 1909, his company was producing about 41,000 kilograms of aluminum a day. As a result of this huge increase of supply, the price of aluminum fell rapidly to about $0.60 per kilogram.

Today, aluminum and aluminum alloys are used in a wide variety of products: cans, foils and kitchen utensils, as well as parts of airplanes, rockets and other items that require a strong, light material. Although it doesn't conduct electricity as well as copper, it is used in electrical transmission lines because of its light weight. It can be deposited on the surface of glass to make mirrors, where a thin layer of aluminum oxide quickly forms that acts as a protective coating. Aluminum oxide is also used to make synthetic rubies and sapphires for lasers.

CHEMISTRY - BONDS MODULE #8

BONDING

Bonding Basics

You must first learn why atoms bond together. We use a concept called "Happy Atoms." We figure that most atoms want to be happy, just like you. 

The idea behind Happy Atoms is that atomic shells like to be full. That's it. If you are an atom and you have a shell, you want your shell to be full. Some atoms have too many electrons (one or two extra). These atoms like to give up their electrons. Some atoms are really close to having a full shell. Those atoms go around looking for other atoms who want to give up an electron. 

Let's take a look at some examples. 

We should start with the atoms that have atomic numbers between 1 and 18. 

There is a 2-8-8 rule for these elements. 

• The first shell is filled with 2 electrons
• the second is filled with 8 electrons
• third is filled with 8. 

You can see that sodium (Na) and magnesium (Mg) have a couple of extra electrons. They, like all atoms, want to be happy. They have two possibilities: they can try to get to eight electrons to fill up their third shell, or they can give up a few electrons and have a filled second shell.

•  It is always easier to give away one or two electrons than it is to go out and find six or seven to fill your shells. 

What a coincidence! Many other atoms are interested in gaining a few extra electrons. 

Oxygen (O) and fluorine (F) are two good examples. Each of those elements is looking for a couple of electrons to make a filled shell. They each have one filled shell with two electrons, but their second shells want to have eight. There are a couple of ways they can get the electrons. 

• They can share electrons, making a covalent bond, or they can just borrow them, and make an ionic bond (also called electrovalent bond). 

So, let’s say we've got a sodium atom that has an extra electron. We've also got a fluorine atom that is looking for one. 

When they work together, they can both wind up happy! Sodium gives up its extra electron. The sodium then has a full second shell and the fluorine (F) also has a full second shell. Two happy atoms! When an atom gives up an electron, it becomes positive like the sodium ion (Na⁺). When an atom gets an extra electron, it becomes negatively charged like the fluorine ion (F^-). 
The positive and negative charges continue to attract each other like magnets. The attraction of opposite charges is the way they form and maintain the bond. 

• Any atoms in an ionic/electrovalent bond can get or give up electrons. 

CHEMISTRY - COMPOUNDS MODULE #9

COMPOUNDS

Compound Basics

Compounds are groups of two or more elements that are bonded together. You have also seen us use the word molecule. 
Molecule is the general term used to describe atoms connected by chemical bonds. 

• Every combination of atoms is a molecule. 
• Compounds happen with atoms from different elements. So, all compounds are molecules, because they have bonds between the atoms, like in water (H₂O).      
• However, not all molecules are compounds because sometimes the atoms are of the same element. 
• Hydrogen gas (H₂) is a good example of a molecule that is not a compound. 

There are two main types of chemical bond that hold atoms together covalent and electrovalent/ionic bonds. 

• Covalent compounds happen when the atoms share the electrons, and
• Ionic compounds happen when electrons are donated from one atom to another. 

When we discuss phase changes in matter, physical forces create the changes. 
When we talk about compounds, bonds are built and broken down by chemical forces. Physical forces alone (unless you're inside of the Sun or something extreme) cannot break down compounds. Chemical forces are forces generated by other compounds or molecules that act on substances. You can apply the physical force of heat to melt an ice cube and there is no change to the water molecules. You can also pour a liquid acid on a solid and watch the solid melt, but that is a chemical change because molecular bonds are being created and destroyed. 

There are millions of different compounds around you. Probably everything you can see is one type of compound or another. When elements join and become compounds, they lose many of their individual traits. 

• Sodium (Na) alone is very reactive. But when sodium and chlorine (Cl) combine, they form a non-reactivesubstance called sodium chloride (salt, NaCl). The compound has few or none of the traits of the original elements. The new compound is not as reactive. It has a new life of its own. 

Different Bonds Abound

Most compounds are made up of combinations of bonds. If you look at sodium chloride, it is held together by one ionic/electrovalent bond. What about magnesium chloride (MgCl₂)? It contains one magnesium (Mg) and two chlorine atoms. There are two ionic bonds. There's a compound called methane (CH₄) that is made up of one carbon (C) and four hydrogen (H) atoms. There are four bonds and they are all covalent. Those examples are very simple compounds, but most compounds are combinations of ionic and covalent bonds. 

Let's look at sodium hydroxide (Na-OH)... 

You can see the sodium (Na) part on the left and the hydroxide (-OH) part on the right. The bond that binds the hydrogen (H) to the oxygen (O) is covalent. The sodium is bonded to the hydroxide part of the compound with an ionic/electrovalent bond. This is a very good example of how there can be different types of bonds within one compound. 


REVIEW: 

A compound is a substance made up of two or more elements combined chemically. 

•  This combination is similar to a recipe for a dessert in which one combines the different ingredients in specific amounts to one another to create a delicious treat!

• Compounds are made up of elements which are a kind of atom or of a combination of compounds. 
• When they are combined chemically, it is very difficult to separate out the different elements just as it is very difficult once a cake is baked to separate out the eggs, flour, sugar and other ingredients.

• Compounds often have common names such as water or salt - but are also named by their formula which tell what elements make up the compound and in what proportion. 
• For example, the smallest bit of water, a molecule of water, is made up of two hydrogen atoms for every one oxygen atom. 
• A formula is similar to a very precise recipe for a compound.

• Compounds are made up of many, many molecules of that compound.

CHEMISTRY - COMPOUND NAMES MODULE #10

COMPOUND NAMES

Whole Lotta Rules Going On

The process of naming compounds is just a set of rules. We're going to show you some of the basics. There are some advanced ways of naming things that we're going to skip right now. 

When you have two different elements, there are usually only two words in the compound name. The first word is the name of the first element. The second word tells you the second element and how many atoms there are in the compound. The second word usually ends in IDE. That's the suffix. When you are working with non-metals likeoxygen (O) and chlorine (Cl), the prefix (section at the beginning of the word) of the second element changes based on how many atoms there are in the compound. It's like this... 

Do you notice anything about the chalkboard? You can see that the prefixes are very similar to the prefixes of geometric shapes. You know what a triangle is. Right? Well the prefix tri- means three. So when you have three chlorine atoms, you would name it trichloride. 

Look at the other names too. You may know about a pentagon, a hexagon, or an octagon. The naming system in chemistry works the same way! 

Let's put these ideas together! Remember, we're only talking about simple compounds with no metal elements. Most simple compounds only have two words in their names. Let's start with carbon monoxide (CO). That name tells you that you have one carbon (C) atom and one oxygen (O) atom (you can also use the prefix MONO to say one atom). Remember that the second word ends in -ide. So... 

(1) Carbon + (1) Oxygen = Carbon monoxide (CO)

Now we'll build on that example. What if you have one carbon (C) and two oxygen (O) atoms? 

(1) Carbon + (2) Oxygen = Carbon dioxide (CO₂)

One last example and we'll call it quits. Now you have one carbon (C) and four chlorine (Cl) atoms. 

(1) Carbon + (4) Chlorine = Carbon tetrachloride (CCl₄)

You should be getting the idea now. The compound name can tell you how many atoms are inside. Take a look at some of the examples and see if you understand what is happening in the name. 

SCIENCE NEWS - SUPERGLUE #20

CHEMISTRY - ELEMENT OF THE DAY - MAGNESIUM

12

Mg

Magnesium

24.3050

Atomic Number: 12

Atomic Weight: 24.3050

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 3    Group Number: 2    

Group Name: Alkaline Earth Metal

What's in a name? For Magnesia, a district in the region of Thessaly, Greece.

Say what? Magnesium is pronounced as mag-NEE-zhi-em.

History and Uses:

Although it is the eighth most abundant element in the universe and the seventh most abundant element in the earth's crust, magnesium is never found free in nature. Magnesium was first isolated by Sir Humphry Davy, an English chemist, through the electrolysis of a mixture of magnesium oxide (MgO) and mercuric oxide (HgO) in 1808. Today, magnesium can be extracted from the minerals dolomite (CaCO₃·MgCO₃) and carnallite (KCl·MgCl₂·6H₂O), but is most often obtained from seawater. Every cubic kilometer of seawater contains about 1.3 billion kilograms of magnesium (12 billion pounds per cubic mile).

Magnesium burns with a brilliant white light and is used in pyrotechnics, flares and photographic flashbulbs. Magnesium is the lightest metal that can be used to build things, although its use as a structural material is limited since it burns at relatively low temperatures. Magnesium is frequently alloyed with aluminum, which makes aluminum easier to roll, extrude and weld. Magnesium-aluminum alloys are used where strong, lightweight materials are required, such as in airplanes, missiles and rockets. Cameras, horseshoes, baseball catchers' masks and snowshoes are other items that are made from magnesium alloys.

Magnesium oxide (MgO), also known as magnesia, is the second most abundant compound in the earth's crust. Magnesium oxide is used in some antacids, in making crucibles and insulating materials, in refining some metals from their ores and in some types of cements. When combined with water (H₂O), magnesia forms magnesium hydroxide (Mg(OH)₂), better known as milk of magnesia, which is commonly used as an antacid and as a laxative.

Hydrated magnesium sulphate (MgSO₄·7H₂O), better known as Epsom salt, was discovered in 1618 by a farmer in Epsom, England, when his cows refused to drink the water from a certain mineral well. He tasted the water and found that it tasted very bitter. He also noticed that it helped heal scratches and rashes on his skin. Epsom salt is still used today to treat minor skin abrasions.

Other magnesium compounds include magnesium carbonate (MgCO₃) and magnesium fluoride (MgF₂). Magnesium carbonate is used to make some types of paints and inks and is added to table salt to prevent caking. A thin film of magnesium fluoride is applied to optical lenses to help reduce glare and reflections.

CHEMISTRY - ISOTOPES - MODULE #7

ISOTOPES

Neutron Madness

We have already learned that ions are atoms that are either missing or have extra electrons. Let's say an atom is missing a neutron or has an extraneutron. That type of atom is called an isotope. An atom is still the same element if it is missing an electron. The same goes for isotopes. They are still the same element. They are just a little different from every other atom of the same element. 

For example, there are a lot of carbon (C) atoms in the Universe. The normal ones are carbon-12. Those atoms have 6 neutrons. There are a few straggler atoms that don't have 6. Those odd ones may have 7 or even 8 neutrons. As you learn more about chemistry, you will probably hear about carbon-14. Carbon-14 actually has 8 neutrons (2 extra). C-14 is considered an isotope of the element carbon. 

Messing with the Mass

If you have looked at a periodic table, you may have noticed that the atomic mass of an element is rarely an even number. That happens because of the isotopes. If you are an atom with an extra electron, it's no big deal. Electrons don't have much of a mass when compared to a neutron or proton. 

Atomic masses are calculated by figuring out the amounts of each type of atom and isotope there are in the Universe. For carbon, there are a lot of C-12, a couple of C-13, and a few C-14 atoms. When you average out all of the masses, you get a number that is a little bit higher than 12 (the weight of a C-12 atom). The average atomic mass for the element is actually 12.011. Since you never really know which carbon atom you are using in calculations, you should use the average mass of an atom. 

Bromine (Br), at atomic number 35, has a greater variety of isotopes. The atomic mass of bromine (Br) is 79.90. There are two main isotopes at 79 and 81, which average out to the 79.90amu value. The 79 has 44 neutrons and the 81 has 46 neutrons. While it won't change the average atomic mass, scientists have made bromine isotopes with masses from 68 to 97. It's all about the number of neutrons. As you move to higher atomic numbers in the periodic table, you will probably find even more isotopes for each element. 

Returning to Normal

If we look at the C-14 atom one more time, we find that C-14 does not last forever. There is a time when it loses its extra neutrons and becomes C-12. The loss of those neutrons is called radioactive decay. That decay happens regularly like a clock. For carbon, the decay happens in a few thousand years (5,730 years). Some elements take longer, and others have a decay that happens over a period of minutes. Archeologists are able to use their knowledge of radioactive decay when they need to know the date of an object they dug up. C-14 locked in an object from several thousand years ago will decay at a certain rate. With their knowledge of chemistry, archeologists can measure how many thousands of years old an object is. This process is called carbon dating. 

CHEMISTRY - ELEMENT OF THE DAY - FLUORINE

9

F

Fluorine

18.9984032

Atomic Number: 9

Atomic Weight: 18.9984032

r

Phase at Room Temperature: Gas

Element Classification: Non-metal

Period Number: 2    Group Number: 17    

Group Name: Halogen

What's in a name? From the Latin and French words for flow, fluere.

Say what? Fluorine is pronounced as FLU-eh-reen or as FLU-eh-rin.

History and Uses:

Fluorine is the most reactive of all elements and no chemical substance is capable of freeing fluorine from any of its compounds. For this reason, fluorine does not occur free in nature and was extremely difficult for scientists to isolate. The first recorded use of a fluorine compound dates to around 1670 to a set of instructions for etching glass that called for Bohemian emerald (CaF₂). Chemists attempted to identify the material that was capable of etching glass and George Gore was able to produce a small amount of fluorine through an electrolytic process in 1869. Unknown to Gore, fluorine gas explosively combines with hydrogengas. That is exactly what happened in Gore's experiment when the fluorine gas that formed on one electrode combined with the hydrogen gas that formed on the other electrode. Ferdinand Frederic Henri Moissan, a French chemist, was the first to successfully isolate fluorine in 1886. He did this through the electrolysis of potassium fluoride (KF) and hydrofluoric acid (HF). He also completely isolated the fluorine gas from the hydrogen gas and he built his electrolysis device completely from platinum. His work was so impressive that he was awarded the Nobel Prize for chemistry in 1906. Today, fluorine is still produced through the electrolysis of potassium fluoride and hydrofluoric acid as well as through the electrolysis of molten potassium acid fluoride (KHF₂).

Fluorine is added to city water supplies in the proportion of about one part per million to help prevent tooth decay. Sodium fluoride (NaF), stannous(II) fluoride (SnF₂) and sodium monofluorophosphate (Na₂PO₃F) are all fluorine compounds added to toothpaste, also to help prevent tooth decay. Hydrofluoric acid (HF) is used to etch glass, including most of the glass used in light bulbs. Uranium hexafluoride (UF₆) is used to separate isotopes of uranium. Crystals of calcium fluoride (CaF₂), also known as fluorite and fluorspar, are used to make lenses to focus infrared light. Fluorine joins with carbon to form a class of compounds known as fluorocarbons. Some of these compounds, such as dichlorodifluoromethane (CF₂Cl₂), were widely used in air conditioning and refrigeration systems and in aerosol spray cans, but have been phased out due to the damage they were causing to the earth's ozone layer.

CHEMISTRY - IONS MODULE #5

IONS
Looking at Ions
We've talked about ions before. Now it's time to get down to basics. The atomic number of an element, also called a proton number, tells you the number of protons or positive particles in an atom. 

A normal atom has a neutral charge with equal numbers of positive and negative particles. That means an atom with a neutral charge is one where the number of electrons is equal to the atomic number. Ions are atoms with extra electrons or missing electrons. When you are missing an electron or two, you have a positive charge. When you have an extra electron or two, you have a negative charge. 

What do you do if you are a sodium (Na) atom? 

• You have eleven electrons — one too many to have an entire shell filled. You need to find another element that will take that electron away from you. When you lose that electron, you will you’ll have full shells. Whenever an atom has full shells, we say it is "happy." 

Let's look at chlorine (Cl). 

• Chlorine has seventeen electrons and only needs one more to fill its third shell and be "happy." Chlorine will take your extra sodium electron and leave you with 10 electrons inside of two filled shells. You are now a happy atom too. You are also an ion and missing one electron. That missing electron gives you a positive charge. You are still the element sodium, but you are now a sodium ion (Na⁺). You have one less electron than your atomic number. 

Ion Characteristics
So now you've become a sodium ion. You have ten electrons. That's the same number of electrons as neon (Ne). But you aren't neon. Since you're missing an electron, you aren't really a complete sodium atom either. As an ion you are now something completely new. Your whole goal as an atom was to become a "happy atom" with completely filled electron shells. Now you have those filled shells. You have a lower energy. You lost an electron and you are "happy." So what makes you interesting to other atoms? Now that you have given up the electron, you are quite electrically attractive. Other electrically charged atoms (ions) of the opposite charge (negative) are now looking at you and seeing a good partner to bond with. That's where the chlorine comes in. It's not only chlorine. Almost any ion with a negative charge will be interested in bonding with you. 

Electrovalence

Don't get worried about the big word. Electrovalence is just another word for something that has given up or taken electrons and become an ion. 

If you look at the periodic table, you might notice that elements on the left side usually become positively charged ions (cations) and elements on the right side get a negative charge (anions). That trend means that the left side has a positive valence and the right side has a negative valence. Valence is a measure of how much an atom wants to bond with other atoms. It is also a measure of how many electrons are excited about bonding with other atoms. 

There are two main types of bonding, covalent and electrovalent. You may have heard of the term "ionic bonds." 

• Ionic bonds are electrovalent bonds. They are just groups of charged ions held together by electric forces. Scientists call these groups "ionic agglomerates." When in the presence of other ions, the electrovalent bonds are weaker because of outside electrical forces and attractions. Sodium and chlorine ions alone have a very strong bond, but as soon as you put those ions in a solution with H⁺, OH^-, F^- or Mg⁺⁺ ions, there are charged distractions that break the Na-Cl bond. 

Look at sodium chloride (NaCl) one more time. 

• Salt is a very strong bond when it is sitting on your table. It would be nearly impossible to break those ionic/electrovalent bonds. However, if you put that salt into some water (H₂O), the bonds break very quickly. It happens easily because of the electrical attraction of the water. Now you have sodium (Na⁺) and chlorine (Cl^-) ions floating around the solution. 
• You should remember that ionic bonds are normally strong, but they are very weak in water. 

REVIEW: 
 
An ion is an atom or group of atoms that have a net electrical charge. 

• An ion is formed when electrons or protons are gained or lost by an atom. 
• This is different than a neutral atom that has equal numbers of protons and electrons so there is no net electrical charge.

• A simple ion is made up of only one charged atom with either a positive or negative charge. 
• A complex ion is one with a number of atoms with a net charge that is positive or negative. 
• If an atom or atoms lose electrons or gain protons, the ion has a positive charge. This kind of ion is called a cation.
•  If an atom or atoms gain electrons or lose protons, the ion will have a negative charge. This kind of ion is called an anion. 
• Ions normally are found as neutral groups of cations and anions combined. This means when the cations and anions charges are added up, the total is zero.

How are ions created from neutral atoms? 

• Some such as salt compounds come apart or dissociate in certain solutions. 
• Substances that form ions in solutions are called electrolytes. 
• Those that don't form ions in solutions are called non-electrolytes. 
• Electrolytes conduct electricity.

Ions can also be formed from neutral atoms with radiation. They can also be formed by having a substance heated to high temperatures.