Chemical Interactions
Chemical Bonds
Elements can form chemical bonds in 3 different ways.
Ionic bonds from when valence electrons are transferred from one element to another. The elements then have opposite charges which are attracted to each other like magnets and form a hard brittle crystal. This usually occurs between a metal and a nonmetal. Ionic compounds conduct electricity when they are dissolved in polar liquids because they separate into the individual charged ions.
Covalent bonds form when two nonmetal share valence electrons and are held together by the attraction of both nuclei for the shared electron. Atoms with greater electronegativities have a stronger pull for the electrons causing partial charges in covalent bonds. We can look at the arrangement of the bonds to determine whether the overall effect is a polar or nonpolar molecule.
Metals bond to one another by forming metallic bonds in which all of the metals give up their valence electrons to form a negatively charged pool of shared electrons which attracts all of the positive metal ions. Since the metal ions can move anywhere in the pool, metals are ductile and malleable.
Ionic bonds from when valence electrons are transferred from one element to another. The elements then have opposite charges which are attracted to each other like magnets and form a hard brittle crystal. This usually occurs between a metal and a nonmetal. Ionic compounds conduct electricity when they are dissolved in polar liquids because they separate into the individual charged ions.
Covalent bonds form when two nonmetal share valence electrons and are held together by the attraction of both nuclei for the shared electron. Atoms with greater electronegativities have a stronger pull for the electrons causing partial charges in covalent bonds. We can look at the arrangement of the bonds to determine whether the overall effect is a polar or nonpolar molecule.
Metals bond to one another by forming metallic bonds in which all of the metals give up their valence electrons to form a negatively charged pool of shared electrons which attracts all of the positive metal ions. Since the metal ions can move anywhere in the pool, metals are ductile and malleable.
Chemical Reactions
Chemical reactions occur when chemical bonds are made or broken in order to create a new substance. Chemical reactions are described by chemical equations which tell you the number of each element/compound involved in the chemical reactions. Chemical equations must be balanced using coefficients so that no atoms are lost or gained in the reaction. The rate of chemical reactions can be controlled by controlling the number of collisions between the reactants. This can be done by modifying the level of concentration, surface area, temperature or agitation. You can also use a catalyst which make the collisions between molecules more effective often by lowering activation energy. Below are some links to help you with the material in this chapter.
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Solubility and Concentration
Mixtures can be classified as heterogeneous and homogeneous, but can also generally fit into the classifications of solution, colloid, and suspension. Solutions are mixtures that are very well mixed and will generally stay mixed unless stressed or modified in some way. Solutions can be described as unsaturated, saturated, and supersaturated as well as dilute or concentrated. The actual concentration of a solution can be expressed in a number of different ways, but we will focus on % by mass using the equation grams of solute/grams of solution * 100 = %.
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Acids, Bases, and Neutralization
Acids are chemicals that produce a hydrogen ion in solution giving them a pH lower then 7. Bases produce a hydroxide ion in solution giving them a pH higher than 7. When acids and bases are mixed, the positive hydrogen ion and the negative hydroxide ion come together to make water and the remain ions come together to make a salt. Neutralization reactions are used in daily life for such things and curing heartburn and decreasing the severity of ant bite (which put formic acid into the victim.
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Organic Chemistry
The group of chemicals that make up living things and contain carbon are generally referred to as organic chemicals. The simplest of these chemicals are called hydrocarbons. They are made up only of hydrogen and carbon and are often used as fuels because they release a lot of energy when burned. Octane is a hydrocarbon consisting of 8 carbons and 18 hydrogens and is the main component in gasoline. Substituted hydrocarbons include things like rubbing alcohol and citric acid. Much of the food that we eat is composed of organic chemicals as well. The websites listed below will help you along when we begin searching the structures and functions of various organic chemical found in our foods.
Organic Chemistry Resources
American Chemical Society
About.com for Chemistry
3-D Chem (helpful for structures)
Drugs.com (helpful for vitamins)
Table with % of each fatty acid in common oils
PubChem (good for structures and some uses)
Web MD (good for functions, uses of vitamins, some oils and some sugars)
American Chemical Society
About.com for Chemistry
3-D Chem (helpful for structures)
Drugs.com (helpful for vitamins)
Table with % of each fatty acid in common oils
PubChem (good for structures and some uses)
Web MD (good for functions, uses of vitamins, some oils and some sugars)