ADITIF
Aditif essence food is substance in food and drink which is useful to improve appeareance.ussually aditif essence didin't have nutrient valve. (Memi malihah)

COLLOID
A colloid is a type of mechanical mixture where one substance is dispersed evenly throughout another. Because of this dispersal, some colloids have the appearance of solutions. A colloidal system consists of two separate phases: a dispersed phase (or internal phase) and a continuous phase (or dispersion medium). A colloidal system may be solid, liquid, or gaseouse. Many familiar substances are colloids, as shown in the below chart. The dispersed-phase particles have at least one dimension which is between 1 nanometre and 1 micrometer. Such particles are normally invisible to a normal microscope, though their presence can be confirmed with the use of an ultramicroscope or an electron microscope. Homogeneous mixtures with a dispersed phase in this size range may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions, or hydrosols. The dispersed-phase particles or droplets are largely affected by the surface chemistry present in the colloid. (Eviana ayu nugroho)

PHENOL
Phenol is both a manufactured chemical and a natural substance. It is a colorless-to-white solid when pure. The commercial product is a liquid. Phenol has a distinct odor that is sickeningly sweet and tarry. You can taste and smell phenol at levels lower than those that are associated with harmful effects. Phenol evaporates more slowly than water, and a moderate amount can form a solution with water. Phenol can catch fire. Phenol is used primarily in the production of phenolic resins and in the manufacture of nylon and other synthetic fibers. It is also used in slimicides (chemicals that kill bacteria and fungi in slimes), as a disinfectant and antiseptic, and in medicinal preparations such as mouthwash and sore throat lozenges. (Eviana ayu nugroho)

IDEAL GAS
An “Ideal Gas” is a simplified “Real Gas” with the following assumption: The Compressibility factor Z is set equal to 1. Thus making the gas incompressible. The state variables will follow the ideal gas law. This approximation is more suitable for applications in engineering although simpler models can be used to produce a "ball-park" range as to where the real solution should lie. An example where the "Ideal gas approximation" would be suitable would be inside a combustion chamber of a jet engine. It may also be useful to keep the elementary reactions and chemical dissociations for calculating emissions.. (Eviana)

SOLID
A solid object is in the states of matter characterized by resistence to deformation and changes of volume at the microscopic scale, a solid has these properties: The atoms or molecules that compose the solid are packed closely together. These constituent element have fixed positions in space relative to each other. This accounts for the solid’s rigidity. In mineralogy and crystallography, a crystal structure is a unique arrangement of atom in a crystal. A crystal structure is composed of unit cell, a set of atoms arranged in a particular way; which is periodically repeated in three dimensions on a lettice. The spacing between unit cells in various direction is called its lettice parameters. Because solids have thermal energy, their atoms vibrate. However, this movement is very small, and cannot be observed or felt under ordinary condition. (lin suciani)

COLLOID
A colloid is a type of mechanical mixture where one substance is dispersed evenly throughout another. Because of this dispersal, some colloid have the appearance of solutions. A colloid system consists of two separate phases: a dispersed phase (or internal phase) and a continuous phase (or dispersion medium). A colloid system may be solid, liquid, or gaseous. Many familiar substances are colloid, as shown in the below chart.(Rida)

CHARCOAL
Charcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by heating wood, sugar, bone char, or others substances in the absence of oxygen. The soft, brittle, lightweight, black, porous material resembles coal and is 85% to 98% carbon with the remainder consisting of volatile chemicals and ash.(Fefi alfiah)

REAL GAS
Real Gas effect refers to an assumption base where the following are taken into account:
• Compressibility effect
• Variable heat capacity
• Van der Wall forces
• Non-equilibrium thermodynamic effects
• Issues with molecular dissociation and elementary reactions with variable composition
For most applications, such a detailed analysis is excessive. An example where “Real Gas Effects” would have a significant impact would be on the Space Shuttle re-entry where extremely high temperatures and pressures are present. (Siti amalia)
CARBON
Carbon is a chemical element with the symbol C and atomic number 6. It is a group 14, nonmetallic, tetravalent element, that presents several allotropic forms of which the best known ones are graphite (the thermodynamically stable form under normal conditions), diamond, and amorphous carbon. There are three naturally occurring isotopes:12C and 13C are stable, and 14C is radioactive, decaying with a half-life of about 5700 years. Carbon is one of the few elements known to man since antiquity. The name "carbon" comes from Latin language carbo, coal, and in some romance languages, the word carbon can refer both to the element and to coal.(Susi susilawati)

ZEOLITE
Zeolite is a mineral with a unique interconnecting lattice structure. This lattice structure is arranged to from a honeycomb framework of consistent diameter interconnecting channels and pores. Negatively charged alumina and neutrally charged silica tetrahedral building blocks are stacked to produce the open there-dimensional honeycomb framework Zeolites actually attract odors and gases and trap them in its crystalline structure.(Rina maryana)

ESSENCE
Essence is reflection, the movement of becoming and transition that remains internal to it, in which the differentiated moment is determined simply that which in itsellf is only negative, as illusory being. At the base of becoming in the sphere of being, there lies the determinateness of being, and this is relation to other. The movement of reflection, on the other hand, is the other as the negation in itself, which has a being only as self-related negation. Or, since the self-relation is precisely this negating of negation, the negation as negation is present in such wise that it has its being in its negatedness, as illusory being (Memi Malihah)

BIOGAS
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel. One type of biogas is produced by anaerobic digestion or fermentation of biodegradable materials such as biomass, manure or sewage, municipal waste, and energy crops. This type of biogas is comprised primarily of methane and carbon dioxide. The other principle type of biogas is wood gas which is created by gasification of wood or other biomass. This type of biogas is comprised primarily of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane. (Nurul Aida)

CHEMISTRYELECTRO
Chemistryelectro is a methode of the chemistry reaction and electric energy in happened with a redoks reaction, while the electron transferring from the reductionisasi to be oksidationisasi. Both of the reaction can we make in to the two holf reaction. (Eka Agustian)

ACID RAIN
Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are produced. The smoke that comes from a fire or the fumes that come out of a car exhaust don't just contain the sooty grey particles that you can see - they also contains lots of invisible gases that can be even more harmful to our environment. Power stations, factories and cars all burn fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen oxides and sulphur dioxide) react with the tiny droplets of water in clouds to form sulphuric and nitric acids. The rain from these clouds then falls as very weak acid - which is why it is known as "acid rain".(SITI MAIMUNAH)
FATTY ACID
Fatty acids are aliphatic monocarboxylic acids, derived from, or contained in esterified form in an animal or vegetable fat, oil or wax. Natural fatty acids commonly have a chain of 4 to 28 carbons (usually unbranched and even numbered), which may be saturated or unsaturated. By extension, the term is sometimes used to embrace all acyclic aliphatic carboxylic acids. (Fefi alfiah)

CARCINOGEN
The term carcinogen refers to any substance, radionuclide or radiation that is an agent directly involved in the promotion of cancer or in the facilitation of its propagation. This may be due to ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit. Common examples of carcinogens are, inhaled asbestos, certain dioxins, and tobacco smoke. (Fefi alfiah)

GLOBAL WARMING
Global warming is perhaps the most important environmental problem in the world today. Levels of greenhouse gases are increasing in the atmosphere due to human activities, and are changing the composition of the atmosphere and global warming. Climate scientists agree that human activities such as the burning of fossil fuels contribute to the problem. Scientists have predicted the phenomemon of global warming for decades. Unfortunately, some of the adverse effects of global warming, they have also predicted begin to occur throughout the world, including: growing incidence of droughts in some areas, floods in others;
• The rising temperatures of oceans and the sea level;
• increase extreme weather events such as tornadoes and hurricanes;
• The melting of mountain glaciers and the reduction of snow cover;
• Dying coral reefs, and
• Coastal erosion, and loss of coastal ecosystems.
(Riska Haryati)


LIPID
Lipid is all compound produced by organism, do not in water of, but earning diekstraksi by pelarut able to dissolving like fat and example: chloroform, heksana, toluen, acetone. Lipid of most found in combination with compound other simple (like wax;candle ester, trigliserida, sterile of and ester fosfolipid), combination with carbohydrate (glikolipid), combination with protein (lipoprotein). Triterpenoid is the born of isoprenoid asiklik skualen (C30H50), intact component from cod, oil vegetable, mushroom .(Diyah Rauhillah Hasni)


CALORIMETRY
Calorimetry is a methode analysis chemistry of basic the similiary colour betwen lateness sampel of lateness standard. The eye detector usually use in calorimetry and to make sure for the consentration sampel in similiary standard lateness colour. The condition of the lateness must be colouring if not, the lateness must be given colour. (Eka Agustian)


PRECIPITATION
Precipitation is the formation of a solid in a solution during a chemical reaction.When the reaction occurs, the solid formed is called the precipitate, and the liquid remaining above the solid is called the supernate. Precipitation reactions can be used for making pigments, removing salts from water in water treatment, and for qualitative chemical analysis. (Rieda Rasyidah)


POLARIZABILITY
Polarizability is the ease of distortion of the electron cloud of a molecular entity by an electric field (such as that due to the proximity of a charged reagent). It is experimentally measured as the ratio of induced dipole moment to the field E which induces it : α = µ ind/E. The units of α are C2 m2 V-1. in ordinary usage the term refers to the “mean polarizability”, the average over three rectilinear axes of the molecule. Polarizabilities in different directions (e.g. along the bond in C12, called “longitudinal polarizability”, and in the direction perpendicular to the bond, called “transverse polarizability”) can be distinguished, at least in principle. Polarizability along the bond joining a substituent to the rest of the molecule is seen in certain modern theoretical approaches as a factor influencing chemical reactivity, etc. and parametrization there of has been proposed. (Nur Cholifah)


A Hydrogen Bond
A hydrogen bond is a special type of dipole-dipole force that exist between electronegative atom and a hydrogen atom bonded to another electronegative atom. This type of force always involves a hydrogen atom and the energy of this attraction is close to that of weak covalent bonds (155 kJ/mol), thus the name – Hydrogen Bonding. These attraction can occur between molecules (intermolecularly), or within different parts of a single molecule (intramolecularly). The hydrogen bond is a very strong fixed dipole-dipole van der Waals-Keesom force, but weaker than covalent, ionic, and metallic bonds. The hydrogen bond is somewhere between a covalent bond and an electrostatic intermolecular attraction. Intermolecular hydrogen bonding is responsible for the high boiling point of water (100 ºC). This is because of the strong hydrogen bond, as opposed to other group 16 hydrides. Intermolecular hydrogen bonding is partly responsible for the secondary, tertiary, and quaternary structures of proteins and nucleic acid. (Nur Cholifah).

INORGANIC CHEMISTRY II

ELECTROLYTE
A chemical compound (salt, acid, or base) that dissociates into electrically charged ions when dissolved in a solvent. The resulting electrolyte (or electrolytic) solution is an ionic conductor of electricity. Very often, the so formed solution itself is simply called an "electrolyte." Also, molten salts and molten salt solutions are often called "electrolyte" when used in electrochemical cells, see ionic liquid.

IRON
The most common and most useful metallic element, being of almost universal occurrence, usually in the form of an oxide (as hematite, magnetite, etc.), or a hydrous oxide (as limonite, turgite, etc.). It is reduced on an enormous scale in three principal forms; viz., cast iron, steel, and wrought iron. Iron usually appears dark brown, from oxidation or impurity, but when pure, or on a fresh surface, is a gray or white metal. It is easily oxidized (rusted) by moisture, and is attacked by many corrosive agents. Symbol Fe (Latin Ferrum). Atomic weight 55.9. Specific gravity, pure iron, 7.86; cast iron, 7.1. In magnetic properties, it is superior to all other substances. (siti mutoharoh)

TITRATION
Titration is a laboratory technique by which we can determine the concentration of an unknown reagent using a standard concentration of another reagent that chemically reacts with the unknown. This standard solution is referred to as the "titrant". We have to have some way to determine when the reaction is complete that we are using. This is referred to as the "end point" or more technically the equivalence point. At that point all the unknown has been reacted with the standard titrant and some kind of chemical indicator must let us know when that point has been arrived at. (Eliawati addawiyah)

MAGNESIUM
A mineral involved in many processes in the body including nerve signaling, the building of healthy bones, and normal muscle contraction. About 350 enzymes are known to depend on magnesium. Magnesium is contained in all unprocessed foods. High concentrations of magnesium are contained in nuts, unmilled grains, dark-green leafy vegetables, legumes such as peas and beans, and fruit. Magnesium is thus readily available in foods that form the basis of a healthful diet. (Chika Rizka)

INORGANIC CHEMISTRY I

INORGANIC CHEMISTRY I

MERCURY
Mercury is one of the basic chemical elements. It is a heavy, silvery metal that is liquid at normal temperatures. Mercury readily forms alloys with other metals, and this makes it useful in processing gold and silver. Much of the impetus to develop mercury ore deposits in the United States came after the discovery of gold and silver in California and other western states in the 1800s. Unfortunately, mercury is also a highly toxic material, and as a result, its use has severely declined over the past 20 years. Its principal applications are in the production of chlorine and caustic soda, and as a component of many electrical devices, including fluorescent and mercury-vapor lamps. (R. Ahmad Zaky El Islami)

ARSENIC

Arsenic : A metallic element that forms a number of poisonous compounds, arsenic is found in nature at low levels mostly in compounds with oxygen, chlorine, and sulfur. These are called inorganic arsenic compounds. Arsenic in plants and animals combines with carbon and hydrogen. This is called organic arsenic. Organic arsenic is usually less harmful than inorganic arsenic. Most arsenic compounds have no smell or special taste. Inorganic arsenic compounds are mainly used to preserve wood. They are also used to make insecticides and weed killers. Copper and lead ores contain small amounts of arsenic. When arsenic enters the environment, it does not evaporate. It gets into air when contaminated materials are burned. It settles from the air to the ground where it does not break down, but can change from one form to another. Most arsenic compounds can dissolve in water. Fish and shellfish build up organic arsenic in their tissues, but most of the arsenic in fish is not toxic. (Taryana)

REDOX

Redox : The proccess oxidation is the metal loses electrons and becomes a cation. The proccess reduction is the non metal gains electrons and becomes an anion. In the reaction, electrons are transferred from the metal to the non metal. (Lin Suciani Astuti).

ANTITOXIN

Antitoxin is an antybody with the ability to neutralize a specific toxin. Antitoxins are produced by certain animal , plants and bacteria. Although they are most effective in neutralizing toxins, they can kill bacteria and other microorganisms. Antitoxins are made within organisms, but can be injected into other organisms, including humans. This procedure involves injecting an animal with a safe amount of a particular toxin. Then, the animal’s body makes the antitoxin needed to neutralize the toxin. Later, the blood is withdrawn from the animal. When the antitoxin is obtained from the blood, it is purified and injected into a human or other animal, inducing passive immunite. To prevent serum sickness, it is often best to use antitoxin generated from the same species (Aditia Muhamad).

EXPERIMENT I ( BIODIESEL SYNTHESIS )

EXPERIMENT I ( BIODIESEL SYNTHESIS )

WHAT IS BIODIESEL
Biodiesel is defined as the mono-alkyl esters of fatty acids derived from vegetable oils or animal fats. In simple terms, biodiesel is the product you get when a vegetable oil or animal fat is chemically reacted with an alcohol to produce a new compound that is known as a fatty acid alkyl ester. A catalyst such as sodium or potassium hydroxide is required. Glycerol is produced as a byproduct. The approximate proportions of the reaction are:

100 lbs of oil + 10 lbs of methanol → 100 lbs of biodiesel + 10 lbs of glycerol

Biodiesel can also be made from other feedstocks:

1. Other vegetable oils such as corn oil, canola (an edible variety of rapeseed) oil, cottonseed oil, mustard oil, palm oil, etc.
2. Restaurant waste oils such as frying oils
3. Animal fats such as beef tallow or pork lard
4. Trap grease (from restaurant grease traps), float grease (from waste water treatment plants), etc.

Transesterification is the process of reacting a triglyceride molecule with an excess of alcohol in the presence of a catalyst (KOH, NaOH, NaOCN3, etc.) to produce glycerin and fatty esters. The mixture of fatty esters produced by this reaction is known as biodiesel.

EXPERIMENT
In the first step of the reaction, the NaOH reacts with methanol in an acid base reaction. The products of this first step of the reaction are a very strong base, sodium methoxide, and water. In the second step, the sodium methoxide breaks the glycerine section from the fatty acid section. The separation of the glycerine portion leads to the formation of three methyl esters (the biodiesel) and glycerol. The NaOH is regenerated as a product in the reaction. The biodiesel and glycerol are immiscible and will separate to form two layers. The glycerol layer will also contain NaOH and excess methanol. The separation of the biodiesel and glycerol layer is fortuitous in that we can easily separate and isolate our biodiesel product from the remaining product mixture.

The following procedure is for synthesizing a biodiesel mini-batch from 100% pure unused vegetable oil. This method can easily be modified for other oils such as canola, olive, soybean peanut etc. You may bring an oil of your choice from home.

1. Warm up 10 mL of 100% pure vegetable oil to about 60°C in a 100 mL beaker. Warming the oil up is not necessary, but increases the reaction rate.
2. Transfer about 2 mL of sodium methoxide solution (be sure the solution is well mixed – should appear cloudy) to a 50 mL beaker with a magnetic stirrer. Stirring gently, add the warm oil. Cover with watch glass and turn up stirrer to position 7 or 8. Stir for about 30 minutes.
3. Transfer the contents of the beaker into a 15 mL plastic centrifuge tube. The mixture will separate into two different layers. The glycerol will sink to the bottom, and the methyl ester (biodiesel) will float to the top. Allow the mixture to sit for about 15 minutes, and then place it in a centrifuge and spin for another 5 minutes (don’t forget to counterbalance the centrifuge). If the layers have not separated continue to centrifuge for another 5 minutes.
4. Using a transfer pipet, carefully draw off the top layer of biodiesel. Make sure not to get glycerol (bottom darker layer) in the biodiesel.
5. Use the IR, NMR and GCMS to identify your products.

For the IR spectrum, your instructor will show you how to operate the machine. Look for presence of a carbonyl group and OH group (due to methanol or glycerol impurity).

For the NMR spectrum, add 3-4 drops of your sample to an NMR tube and then add 0.7 mL of CDCl3 (deuterochloroform, a common NMR solvent). On the library there is an NMR spectrum of pure vegetable oil. Compare your spectrum to this to determine if you produced biodiesel.

For the mass spectroscopy, place 4 mL of methylene chloride and 1 drop of your product into the special mass spec vial (provided by your instructor). Note the number on the vial. Cap and return the vial to your instructor. Your sample will be analyzed by the autosampler within the next two days.

ADI RIYADHI ( http://chemistrywan.blogspot.com )

BASIC CHEMISTRY VII

BASIC CHEMISTRY VII

SCOPE OF THE OCTET RULE
It must be emphasized that the octet rule does not describe the electronic configuration of all compounds. The very existence of any compounds of the noble gases is evidence that the octet rule does not apply in all cases. Other examples of compounds that do not obey the octet rule are BF3, PF5, and SF6. But the octet rule does summarize, systematize, and explain the bonding in so many compounds that it is well worth learning and understanding. Compounds in which atoms attain the configuration of helium (the duets) are considered to obey the octet rule, despite the fact that they achieve only the duet characteristic of the complete first shell of electrons.

DISTINCTION BETWEEN IONIC AND COVALENT BONDING
The word bonding applies to any situation in which two or more atoms are held together in such close proximity that they form a characteristic species which has distinct properties and which can be represented by a chemical formula. In compounds consisting of ions, bonding results from the attractions between the oppositely charged ions. In such compounds in the solid state, each ion is surrounded on all sides by ions of the opposite charge. In a solid ionic compound, it is incorrect to speak of a bond between specific pairs of ions, and ionic compounds do not form molecules. In contrast, covalent bonding involves the sharing of electron pairs between two specific atoms, and it is possible to speak of a definite bond. For example, in molecules of HCl and CH4 there are one and four covalent bonds per molecule, respectively.

BASIC CHEMISTRY VII

BASIC CHEMISTRY VII

SCOPE OF THE OCTET RULE
It must be emphasized that the octet rule does not describe the electronic configuration of all compounds. The very existence of any compounds of the noble gases is evidence that the octet rule does not apply in all cases. Other examples of compounds that do not obey the octet rule are BF3, PF5, and SF6. But the octet rule does summarize, systematize, and explain the bonding in so many compounds that it is well worth learning and understanding. Compounds in which atoms attain the configuration of helium (the duets) are considered to obey the octet rule, despite the fact that they achieve only the duet characteristic of the complete first shell of electrons.

DISTINCTION BETWEEN IONIC AND COVALENT BONDING
The word bonding applies to any situation in which two or more atoms are held together in such close proximity that they form a characteristic species which has distinct properties and which can be represented by a chemical formula. In compounds consisting of ions, bonding results from the attractions between the oppositely charged ions. In such compounds in the solid state, each ion is surrounded on all sides by ions of the opposite charge. In a solid ionic compound, it is incorrect to speak of a bond between specific pairs of ions, and ionic compounds do not form molecules. In contrast, covalent bonding involves the sharing of electron pairs between two specific atoms, and it is possible to speak of a definite bond. For example, in molecules of HCl and CH4 there are one and four covalent bonds per molecule, respectively.

BASIC CHEMISTRY VI

BASIC CHEMISTRY VI

IONS
The electronic configuration of a potassium atom is

K : 2 8 8 1 ( 1s2 2s2 2p6 3s2 3p6 4s1 )

It is readily seen that if a potassium atom were to lose one electron, the resulting species would have the configuration

K+ : 2 8 8 0 ( 1s2 2s2 2p6 3s2 3p6 4s0 )

or more simply

K+ : 2 8 8 ( 1s2 2s2 2p6 3s2 3p6 )

The nucleus of a potassium atom contains 19 protons, and if there are only 18 electrons surrounding the nucleus after the atom has lost one electron, the atom will have a net charge of 1+. An atom (or group of atoms) that contains a net charge is called an ion. In chemical notation, an ion is represented by the symbol of the atom with the charge indicated as a superscript to the right. Thus, the potassium ion is written K+. Ions that have the electronic configurations of noble gases are rather stable. Note the very important differences between a potassium ion and an argon atom, the different nuclear charges and the net 1+ charge on K+. The K+ ion is not as stable as the Ar atom.


COVALENT BONDING
The element hydrogen exists in the form of diatomic molecules, H2. Since both hydrogen atoms are identical, they are not likely to have opposite charges. (Neither has more electron-attracting power than the other.) Each free hydrogen atom contains a single electron, and if the atoms are to achieve the same electronic configuration as atoms of helium, they must each acquire a second electron. If two hydrogen atoms are allowed to come sufficiently close to each other, their two electrons will effectively belong to both atoms. The positively charged hydrogen nuclei are attracted to the pair of electrons shared between them, and a bond is formed. The bond formed from the sharing of a pair of electrons (or more than one pair) between two atoms is called a covalent bond. The hydrogen molecule is more stable than two separate hydrogen atoms. By sharing a pair of electrons, each hydrogen atom acquires a configuration analogous to that of a helium atom. Other pairs of nonmetallic atoms share electrons in the same way.

BASIC CHEMISTRY V

BASIC CHEMISTRY V

CHEMICAL FORMULAS

Chemical formulas yield the following information:

1. Which elements are present
2. The ratio of the number of atoms of each element to the number of atoms of each other element
3. The number of atoms of each element per formula unit of compound
4. The fact that all the atoms represented are bonded together in some way

You cannot tell from a formula how many atoms of each element are present in a given sample of substance, because there might be a little or a lot of the substance present. The formula tells the ratio of atoms of each element to all the others, and the ratio of atoms of each element to formula units as a whole.

THE OCTET RULE
The elements helium, neon, argon, krypton, xenon, and radon, known as the noble gases, occur in nature as monatomic gases. Their atoms are not combined with atoms of other elements or with other atoms like themselves. The charge on the nucleus and the number of electrons in the valence shell determine the chemical properties of the atom. The electronic configurations of the noble gases (except for that of helium) correspond to a valence shell containing eight electrons, a very stable configuration called an octet. Atoms of other main group elements tend to react with other atoms in various ways to achieve the octet. The tendency to achieve an octet of electrons in the outermost shell is called the octet rule. If the outermost shell is the first shell, that is, if there is only one shell occupied, then the maximum number of electrons is two. A configuration of two electrons in the first shell, with no other shells occupied by electrons, is stable.

BASIC CHEMISTRY IV

BASIC CHEMISTRY IV

ATOMIC THEORY (John Dalton)
In 1804, John Dalton proposed the existence of atoms. He not only postulated that atoms exist, as had ancient Greek philosophers, but he also attributed to the atom certain properties. His postulates were as follows:

1. Elements are composed of indivisible particles, called atoms.
2. All atoms of a given element have the same mass, and the mass of an atom of a given element is different from the mass of an atom of any other element.
3. When elements combine to form a given compound, the atoms of one element combine with those of the other element(s) in a definite ratio to form molecules. Atoms are not destroyed in this process.
4. Atoms of two or more elements may combine in different ratios to form different compounds.
5. The most common ratio of atoms is 1:1, and where more than one compound of two or more elements exists, the most stable is the one with 1:1 ratio of atoms. (This postulate is incorrect.)

ATOMIC STRUCTURE
From 50 to 100 years after Dalton proposed his theory, various discoveries were made that show that the atom is not indivisible, but really is composed of parts. Natural radioactivity and the interaction of electricity with matter are two different types of evidence for this subatomic structure. The most important subatomic particles are Proton (+1) , Neutron (0), and Electron (-1), along with their most important properties. The protons and neutrons are found in a very tiny nucleus (plural, nuclei). The electrons are found outside the nucleus.

ISOTOPES
Atoms having the same number of protons but different numbers of neutrons are called isotopes of one another. The number of neutrons does not affect the chemical properties of the atoms appreciably, so all isotopes of a given element have essentially the same chemical properties. Different isotopes have different masses (contrary to Dalton’s second postulate) and different nuclear properties, however. The sum of the number of protons and the number of neutrons in the isotope is called the mass number of the isotope. Mass number is symbolized A. Isotopes are usually distinguished from one another by their mass numbers, given as a superscript before the chemical symbol for the element. Carbon-12 is an isotope of carbon with a symbol 12C.

PERIODIC TABLE
The periodic table is an extremely useful tabulation of the elements. It is constructed so that each vertical column contains elements that are chemically similar. The elements in the columns are called groups, or families. (Elements in some groups can be very similar to one another. Elements in other groups are less similar. For example, the elements of the first group resemble one another more than the elements of the fourth group from the end, headed by N.) Each row in the table is called a period. There are three distinct areas of the periodic table—the main group elements, the transition group elements, and the inner transition group elements

ELECTRONIC STRUCTURE
The arrangement of electrons in successive energy levels in the atom provides an explanation of the periodicity of the elements, as found in the periodic table. The charges on the nuclei of the atoms increase in a regular manner as the atomic number increases. Therefore, the number of electrons surrounding the nucleus increases also. The number and arrangement of the electrons in the outermost shell of an atom vary in a periodic manner. For example, all the elements in Group IA (H, Li, Na, K, Rb, Cs, Fr) corresponding to the elements that begin a new row or period, have electronic configurations with a single electron in the outermost shell, specifically an s subshell.

H = 1s1
Li = 1s2 2s1
Na = 1s2 2s2 2p6 3s1
K = 1s2 2s2 2p6 3s2 3p6 4s1
Rb = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1
Cs = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1
Fr = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f 14 5d10 6p6 7s1

The noble gases, located at the end of each period, have electronic configurations of the type ns2 np6, where n represents the number of the outermost shell. Also, n is the number of the period in the periodic table in which the element is found.

BASIC CHEMISTRY III

BASIC CHEMISTRY III

SUBSTANCES
There are two kinds of substances-elements and compounds. Elements are substances that cannot be broken down into simpler substances by ordinary chemical means. Elements cannot be made by the combination of simpler substances. There are slightly more than 100 elements, and every material object in the universe consists of one or more of these elements. Familiar substances that are elements include carbon, aluminum, iron, copper, gold, oxygen, and hydrogen.

COMPOUNDS
Compounds are substances consisting of two or more elements chemically combined in definite proportions by mass to give a material having a definite set of properties different from that of any of its constituent elements. For example, the compound water consists of 88.8% oxygen and 11.2% hydrogen by mass. The physical and chemical properties of water are distinctly different from those of both hydrogen and oxygen. For example, water is a liquid at room temperature and pressure, while the elements of which it is composed are gases under these same conditions. Chemically, water does not burn; hydrogen may burn explosively in oxygen (or air). Any sample of pure water, regardless of its source, has the same composition and the same properties.

MIXTURES
There are two kinds of mixtures-homogeneous mixtures and heterogeneous mixures. Homogeneous mixtures are also called solutions, and heterogeneous mixtures are sometimes simply called mixtures. In heterogeneous mixtures, it is possible to see differences in the sample merely by looking, although a microscope might be required. In contrast, homogeneous mixtures look the same throughout the sample, even under the best optical microscope.

BASIC CHEMISTRY II

BASIC CHEMISTRY II

PROPERTIES
Every substance has certain characteristics that distinguish it from other substances and that may be used to establish that two specimens are the same substance or different substances. Those characteristics that serve to distinguish and identify a specimen of matter are called the properties of the substance. For example, water may be distinguished easily from iron or gold, and-although this may appear to be more difficult-iron may readily be distinguished from gold by means of the different properties of the metals.

PHYSICAL PROPERTIES
The properties related to the state (gas, liquid, or solid) or appearance of a sample are called physical properties. Some commonly known physical properties are density, state at room temperature, color, hardness, melting point, and boiling point. The physical properties of a sample can usually be determined without changing its composition. Many physical properties can be measured and described in numerical terms, and comparison of such properties is often the best way to distinguish one substance from another.

CHEMICAL PROPERTIES
A chemical reaction is achange in which at least one substance changes its composition and its set of properties. The characteristic ways in which a substance undergoes chemical reaction or fails to undergo chemical reaction are called its chemical properties. Examples of chemical properties are flammability, rust resistance, reactivity, and biodegradability.

BASIC CHEMISTRY I

BASIC CHEMISTRY I

ELEMENT
An element is a substance that can not be broken down into simpler substances by ordinary means. A few more than 100 elements and the many combinations of these elements-compounds or mixtures-account for all the materials of the world. Exploration of the moon has provided direct evidence that the earth’s satellite is composed of the same elements as those on earth. Indirect evidence, in the form of light received from the sun and stars, confirms the fact that the same elements make up the entire universe. Before it was discovered on the earth, helium (from the Greek helios, meaning “sun”) was discovered in the sun by the characteristic light it emits.

MATTER AND ENERGY
Chemistry focuses on the study of matter, including its composition, its properties, its structure, the changes that it undergoes, and the laws governing those changes. Matter is anything that has mass and occupies space. Any material object, no matter how large or small, is composed of matter. Incontrast, light, heat, and sound Are forms of energy. Energy is the ability to produce change. Whenever a change of any kind occurs, energy is
involved; and whenever any form of energy is changed to another form, it is evidence that a change of some kind is occurring or has occurred.