Properties of Ionic and Covalent Compounds

If you know the chemical formula of a compound, you can predict whether it contains ionic bonds, covalent bonds of a mixture of bond types. Nonmetals bond to each other via covalent bonds while oppositely charged ions, such as metals and nonmetals, form ionic bonds. Compounds which contain polyatomic ions may have both ionic and covalent bonds.

But, how do you know if a compound is ionic or covalent just by looking at a sample? This is where the properties of ionic and covalent compounds can be useful. Because there are exceptions, you need to look at several properties to determine whether a sample is ionic or covalent, but here are some characteristics to consider: Most crystals are ionic compounds. This is because the ions in these compounds tend to stack into crystal lattices to balance between the attractive forces between opposite ions and the repulsive forces between like ions. Covalent or molecular compounds can exist as crystals, though. Examples include sugar crystals and diamond. Ionic compounds tend to have higher melting and boiling points than covalent compounds. Ionic compounds tend to be hard and brittle while covalent compounds tend to be softer and more flexible. Ionic compounds conduct electricity when dissolved in water while covalent compounds typically don't. This is because covalent compounds dissolve into molecules while ionic compounds dissolve into ions, which can conduct charge. These links offer more properties, examples and exceptions. Also, feel free to post additional information that you think might be helpful to others.

Properties of Covalent Compounds | Properties of Ionic Compounds

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Make Blue Crystals Like AMC's Breaking Bad Crystal Meth

AMC did not use real crystal meth for the television show Breaking Bad. Instead, they used blue crystal candy for Walt's (Heisenberg's) signature blue product. Do you want to make your own blue crystals to munch on during the show or for a Breaking Bad party?... Here's howif(zs>0){if(zSbL250)gEI("spacer").style.height=Math.floor(e[0].height/12)+17.5+'em';else{var zIClns=[];function walkup(e){if(e.className!='entry'){if(e.nodeName=='A'||e.style.styleFloat=='right'||e.style.cssFloat=='right'||e.align=='right'||e.align=='left'||e.className=='alignright'||e.className=='alignleft')zIClns.push(e);walkup(e.parentNode)}}walkup(e[0]);if(zIClns.length){node=zIClns[zIClns.length-1];var clone=node.cloneNode(true);node.parentNode.removeChild(node);getElementsByClassName("entry",gEI("articlebody"))[0].insertBefore(clone,gEI("spacer"))}}}};zSB(2);zSbL=0

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Who Is the Father of Chemistry?

If you're ever asked to identify the Father of Chemistry for a homework assignment, the "most correct" answer for a test will be the one found in your textbook. However, that may not be the answer others would give when asked the question.

The first chemist actually was a Mesopotamian woman, Tapputi, who described the process of distillation. She might be called the Mother of Chemistry, but really didn't engage in science in the modern sense of the word. Jabir ibn Hayyan or "Geber", as he was also called, applied the scientific method to the study of alchemy circa 800 AD. Many people consider him to be the Father of Chemistry. Another popular choice for the title of Father of Chemistry is Antoine Lavoisier, who listed elements, described properties of matter, helped to revise and standardize chemistry nomenclature and made a host of other contribution to the field of chemistry. Lavoisier sometimes is known as the Father of Modern Chemistry, to distinguish his work from contributions made before chemistry was a true science.

Geber and Lavoisier aren't the only people who have been called the "Father of Chemistry." Other investigators may be known by this name... Read more

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Burning Dandelion Bouquet

I continued my experimentation into the colors of flames produced by dandelions with a bouquet of 'wishes' or seed heads. In Nebraska, dandelions are used for dandelion wine, but mainly are a weed. No one objected to getting the flowers cleared out their yard. Actually, I suspect they were glad the seed heads were going to be burned. The bouquet is pretty, burns instantly, and leaves little residue.

Fire Projects | Make a Glowing Flower

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Did You Know: Taurine Is Not an Amino Acid

It's commonly believed that taurine is an amino acid. There are a few reasons for the misconception. The chemical name for taurine is 2-aminoethanesulfonic acid, so it has an amino group and is an acid. Taurine has the "-ine" ending that is common with other amino acids, plus it is a nutritional supplement. However, the molecule does not have the amino acid structure. Taurine has a sulfonic acid group rather than the carboxyl group found in amino acids.

Taurine is an important molecule in people and animals. It accounts for about 0.1% of total human body weight. It is a major component of bile and is used to moderate calcium signaling, osmoregulation, and proper muscle function. Human can synthesize taurine from the amino acid cysteine. However, cats and other carnivores cannot, so they have to obtain it from their diet. Taurine is important for development of other animals, too. Some birds seek out taurine-rich spiders to feed to their young.

Image: Chemistry Cat, like all other felines, needs taurine in his diet. Insufficient taurine leads to blindness, loss of fur, tooth decay, and eventually death.

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Difference Between Double-Acting and Single-Acting Baking Powder

If you're like me, you're lucky to pay attention to a recipe enough to notice whether you're supposed to be using baking powder or baking soda. Both ingredients cause baked goods to rise, but they are not interchangeable. Also, there is more than one type of baking powder. You can find single-acting baking powder and double-acting baking powder. You may be wondering how they are different or whether you should use half as much double-acting baking powder as single-acting baking powder.

You use the exactly same amount of double-acting baking powder as you would single-acting baking powder. The difference between the two types of powder is their chemical composition and whether they produce the carbon dioxide gas bubbles that make your baked goods rise when the ingredients are mixed or when the product is heated in the oven. Both types of baking powder produce the same amount of gas, so they are equally effective as leavening agents.

Single-acting baking powder reacts with a water-based ingredient to form bubbles as soon as the ingredients are mixed. If you wait too long to bake your food or mix it too long these bubbles will escape and your food will fall flat.

Double-acting baking powder produces some bubbles when the ingredients are mixed, but most of the rising occurs once heat is applied. This product is more reliable for home baking because it is harder to overbeat the ingredients and the recipe is less susceptible to fail if you forgot to preheat your oven. Because it is practically failsafe, this is the type of baking powder most often found in stores. You'll encounter single-acting baking powder in commercial applications, plus this is the type of powder you would make if you prepare baking powder yourself.

Baking Powder Versus Baking Soda | Ingredient Substitutions

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Do Dandelions Burn in Colors?

Have you seen the photo of a dandelion that appears to be burning in different colors? If you look online, you'll find the original photo, taken by Gregory Gomer, which shows a dandelion burning in usual fire colors. So, the viral image appears to have been Photoshopped or otherwise enhanced. It's still a great excuse for a fire experiment!

For the past few weeks, I've burned every 'wish dandelion' or dandelion seed head that I could find in South Carolina, Texas, and Nebraska. I've burned dandelions from ditches, dandelions from fields, dandelions treated with chemicals, and dandelions spritzed with flame colorants. A couple of my results are shown above. While you can get a dandelion to burn in multiple colors, the colors seem restricted to shades of orange, yellow and red. My next test is to burn a whole bouquet of dandelions, just in case I haven't been using a large enough sample size.

Have you burned dandelions trying to get the color effect? Have you seen anything unusual?

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