Chemical formula: Wikis

  

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Al2(SO4)3
Example of a
chemical formula
.A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound.^ Therefore, all compounds have formula weights, i.e., a way of expressing the weight based on the formula.
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^ A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound .
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^ A chemical formula is a way of expressing information about the atoms that constitute a particular chemical compound , and how the relationship between those atoms changes in chemical reactions .
  • Chemical formula - Cerámica Wiki 6 February 2010 10:52 UTC ceramica.wikia.com [Source type: Reference]

.The chemical formula identifies each constituent element by its chemical symbol and indicates the number of atoms of each element found in each discrete molecule of that compound.^ Molecular Formula - actual numbers of atoms of each element present in a molecule of the compound   .
  • Chapter 02 Chemical Formulas & Composition Stoichiometry 6 February 2010 10:52 UTC www.scribd.com [Source type: Academic]

^ A chemical formula is a shorthand way of using symbols of atoms to identify   molecule.

^ A formula represents the relative numbers of atoms of each element in a substance.
  • Atom element molecule compounds pure impure mixture, meaning definitions physical change, evidence chemical change 6 February 2010 10:52 UTC www.docbrown.info [Source type: Reference]

.If a molecule contains more than one atom of a particular element, this quantity is indicated using a subscript after the chemical symbol (although 18th-century books often used superscripts) and also can be combined by more chemical elements.^ If there is only one of a type of atom, no subscript is used.
  • Chemistry : Chapter 4 : Overview 6 February 2010 10:52 UTC www.wwnorton.com [Source type: Reference]

^ A chemical formula is a shorthand way of using symbols of atoms to identify   molecule.

^ Chemical Symbol : A notation using one to three letters to represent an element.

.Chemical formulas may be used in chemical equations to describe chemical reactions.^ Chemical structure can be represented using a structural formula.

^ Chemical formulas may be used in chemical equations to describe chemical reactions.
  • what is the chemical formula from 30g of NaOH and 100ml of 40% ethanol 6 February 2010 10:52 UTC askville.amazon.com [Source type: General]

^ I use to help construct a chemical formula.
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.For ionic compounds and other non-molecular substances an empirical formula may be used, in which the subscripts indicate the ratio of the elements.^ All compounds have empirical formulas.
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^ Notice that the molecular formula is twice that of the empirical formula.

^ Not all compounds have molecular formulas.
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.The 19th-century Swedish chemist Jöns Jakob Berzelius worked out this system for writing chemical formulas.^ Write the chemical formula for the following: .
  • Chemical Names and Formulas 6 February 2010 10:52 UTC www.hse.k12.in.us [Source type: Reference]

^ Write the names and chemical formulas for 4 of the diatomic 7 .
  • Chemical Names and Formulas 6 February 2010 10:52 UTC www.hse.k12.in.us [Source type: Reference]

^ Write the Chemical Formula for the following: .
  • Chemical Names and Formulas 6 February 2010 10:52 UTC www.hse.k12.in.us [Source type: Reference]

Contents

Molecular geometry and structural formulas

.The exact connectivity among the atoms in a molecule and/or the exact spatial arrangement of those atoms is of utmost importance.^ The exact connectivity among the atoms in a molecule and/or the exact spacial arrangement of those atoms is of utmost importance.
  • Chemical formula - Cerámica Wiki 6 February 2010 10:52 UTC ceramica.wikia.com [Source type: Reference]

^ A chemical formula supplies information about the types and spatial arrangement of bonds in the chemical, though it does not necessarily specify the exact isomer .
  • Chemical formula - Cerámica Wiki 6 February 2010 10:52 UTC ceramica.wikia.com [Source type: Reference]

^ In the   water molecule, two hydrogen atoms, each   in a small circle connect to a darkened   circle representing one oxygen atom.

.Two molecules composed of the same numbers of the same types of atoms might have completely different chemical and/or physical properties if the atoms are connected differently or in different positions.^ For example, the formula H 2 O   shows that the molecule is composed of two H atoms and one O atom.

^ Molecules can be composed of two atoms of one element (known as molecules ) or can be a combination of diatomic atoms of different elements.
  • Chemical Properties of Minerals 6 February 2010 10:52 UTC www.minerals.net [Source type: Reference]

^ The expression that shows the number and kind of each atom in a molecule is the chemical formula .
  • Chemistry : Chapter 4 : Overview 6 February 2010 10:52 UTC www.wwnorton.com [Source type: Reference]

.Thus, sometimes one needs to use a structural formula to illustrate which atoms are bonded to which other ones and somehow describe the resulting molecular geometry of the compound.^ Molecular and structural formula .
  • Chemical formula: Encyclopedia of chemistry, analytics & pharmaceutics with 64,557 entries. 6 February 2010 10:52 UTC www.chemie.de [Source type: Reference]

^ Chemical structure can be represented using a structural formula.

^ Not all compounds have molecular formulas.
  • Chemical Formulas 6 February 2010 10:52 UTC www.neoam.cc.ok.us [Source type: FILTERED WITH BAYES]

For example methane, a simple molecule consisting of one carbon atom bonded to four hydrogen atoms, has the chemical formula:
CH4 or H4C
and glucose with six carbon atoms, twelve hydrogen atoms and six oxygen atoms has the chemical formula:
C6H12O6.
.A chemical formula supplies information about the types and spatial arrangement of bonds in the chemical, though it does not necessarily specify the exact isomer.^ A chemical formula supplies information about the types and spatial arrangement of bonds in the chemical, though it does not necessarily specify the exact isomer .
  • Chemical formula - Cerámica Wiki 6 February 2010 10:52 UTC ceramica.wikia.com [Source type: Reference]

^ There are three types of chemical bonds : .
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^ In learning how to write chemical formulas, you will make use of the oxidation numbers that you learned about in lesson 5-2 .
  • Lesson 5-3 Writing Chemical Formulas 6 February 2010 10:52 UTC www.fordhamprep.org [Source type: Reference]

.For example ethane consists of two carbon atoms single-bonded to each other, with each carbon atom having three hydrogen atoms bonded to it.^ H 2 O 2 has two oxygen atoms connected to each other.

^ Each hydrogen atom is attached to an oxygen atom by a bond.
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^ The ease with which carbon atoms form bonds to other carbon atoms.

.Its chemical formula can be rendered as CH3CH3.^ Its chemical formula can be rendered as CH 3 CH 3 .
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  • What is a Chemical Formula 6 February 2010 10:52 UTC www.worldofmolecules.com [Source type: Reference]
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^ Chemical Formula: CH 3 (CH 2 ) 16 COOH .
  • Ingredients -- Stearic acid 6 February 2010 10:52 UTC sci-toys.com [Source type: Reference]

^ If there were a double bond between the carbon atoms (and thus each carbon only had two hydrogens), the chemical formula may be written: CH 2 CH 2 , and the fact that there is a double bond between the carbons is assumed.
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.In ethylene there is a double bond between the carbon atoms (and thus each carbon only has two hydrogens), therefore the chemical formula may be written: CH2CH2, and the fact that there is a double bond between the carbons is implicit because carbon has a valence of four.^ There are hydrogen atoms in the reactants and only hydrogen atoms in the products.
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^ This formula indicates that there are two hydrogen atoms and one oxygen atom in the compound.
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^ Each hydrogen atom is attached to an oxygen atom by a bond.
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.However, a more explicit and correct method is to write H2C=CH2 or less commonly H2C::CH2.^ However, a more explicit and correct method is to write H 2 C=CH 2 or less commonly H 2 C :: CH 2 .
  • Chemical formula - Cerámica Wiki 6 February 2010 10:52 UTC ceramica.wikia.com [Source type: Reference]

^ If we wanted to be more accurate we would write "17.0" grams, meaning greater than or equal to 16.95 grams and less than or equal to 17.05 grams.
  • BioEd Online Slides: "formula", solutions, Chemistry, formulas, mole 6 February 2010 10:52 UTC www.bioedonline.org [Source type: Reference]

^ More commonly, especially for rare or expensive naturally occurring substances, it is necessary to synthesize the substance from less-expensive or more-available raw materials.
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.The two lines (or two pairs of dots) indicate that a double bond connects the atoms on either side of them.^ H 2 O 2 has two oxygen atoms connected to each other.

^ The covalent bond can be represented by a pair of dots between the atoms, Cl:Cl, or a line between them, Cl-Cl.
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^ The two lines (or two pairs of dots) indicate that a double bond connects the atoms on either side of them.
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.A triple bond may be expressed with three lines or pairs of dots, and if there may be ambiguity, a single line or pair of dots may be used to indicate a single bond.^ A triple bond may be expressed with three lines or pairs of dots, and if there may be ambiguity, a single line or pair of dots may be used to indicate a single bond.
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^ No portion of this site may be copied, retransmitted, reposted, duplicated or otherwise used without the express written permission of GlobalSpec Inc.
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^ Covalent bonds can come in double (sharing of two pairs of electrons) and triple (three pairs of electrons) bonds.
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Carbon chain
.Molecules with multiple functional groups that are the same may be expressed in the following way: (CH3)3CH. However, this implies a different structure from other molecules that can be formed using the same atoms (isomers).^ Allotropes: different structural form of the same element.

^ Grouped water molecules form bodies of water.
  • Chemical Properties of Minerals 6 February 2010 10:52 UTC www.minerals.net [Source type: Reference]

^ Archivo:Chemformula.gif Molecules with multiple functional groups that are the same may be expressed in the following way: (CH 3 ) 3 CH. However, this implies a different structure from other molecules that can be formed using the same atoms (isomers).
  • Chemical formula - Cerámica Wiki 6 February 2010 10:52 UTC ceramica.wikia.com [Source type: Reference]

.The formula (CH3)3CH implies a chain of three carbon atoms, with the middle carbon atom bonded to another carbon (see image of 4 carbon "C" atoms), and the remaining bonds on the carbons all leading to hydrogen atoms (hydrogen atoms are not shown in image).^ Use the prefixes di -, tri -, and tetra - to describe substituents that are found two, three, or four times on the same chain of carbon atoms.

^ We start by breaking the bond in an H 2 molecule so that one of the electrons ends up on each of hydrogen atoms.

^ Replacing one of the hydrogens of water by a more electronegative atom increases the acidity of the remaining O–H bond.
  • Electron Configurations & The Periodic Table 6 February 2010 10:52 UTC www.cem.msu.edu [Source type: Reference]

.However, the same number of atoms (10 hydrogens and 4 carbons, or C4H10) may be used to make a straight chain: CH3CH2CH2CH3.^ Parentheses may be used to group atoms.
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^ CH 4 is composed of 1 carbon atom combined with 4 hydrogen atoms .
  • Atom element molecule compounds pure impure mixture, meaning definitions physical change, evidence chemical change 6 February 2010 10:52 UTC www.docbrown.info [Source type: Reference]

^ However, the same number of atoms (10 hydrogens and 4 carbons, or C 4 H 10 ) may be used to make a straight chain: CH 3 CH 2 CH 2 CH 3 .
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  • Chemical formula: Encyclopedia of chemistry, analytics & pharmaceutics with 64,557 entries. 6 February 2010 10:52 UTC www.chemie.de [Source type: Reference]
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.The alkene but-2-ene has two isomers which the chemical formula CH3CH=CHCH3 does not identify.^ Does MathType 6 manage chemical formulas ?
  • Chemical Formulas - Ask.com 6 February 2010 10:52 UTC www.ask.com [Source type: General]

^ The alkene but-2-ene has two isomers which the chemical formula CH 3 CH=CHCH 3 does not identify.
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  • Chemical formula: Encyclopedia of chemistry, analytics & pharmaceutics with 64,557 entries. 6 February 2010 10:52 UTC www.chemie.de [Source type: Reference]

^ What does a chemical formula stand for?
  • Help What is the chemical formula for plumbite? 6 February 2010 10:52 UTC www.maybenow.com [Source type: FILTERED WITH BAYES]

.The relative position of the two methyl groups must be indicated by additional notation denoting whether the methyl groups are on the same side of the double bond (cis or Z) or on the opposite sides from each other (trans or E).^ Task 2 The Z,Z- forms of bilirubin must have the two higher priority groups on the same side of the double bond.
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^ The Z,E-isomer must, of course, have the higher priority groups on the same side of the Z- double bond and the higher priority groups on opposite sides of the E- double bond.
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^ In contrast, the E,E- bilirubin isomer must have the higher priority groups on opposite sides of the double bond.
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Polymers

.For polymers, parentheses are placed around the repeating unit.^ Polymers are indicated with the molecular formula of the repeating unit(s) in parentheses to which is appended an "x".
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^ For polymers , parentheses are placed around the repeating unit.
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^ If more than one of these ions appears in a compound, parentheses are placed   around the ion to help in identifying it in a formula.

.For example, a hydrocarbon molecule that is described as: CH3(CH2)50CH3, is a molecule with fifty repeating units.^ For example methane, a simple molecule consisting of one carbon atom bonded to four hydrogen atoms has the chemical formula: CH 4 .
  • Calculations and the Chemical Equation 6 February 2010 10:52 UTC www.chem.latech.edu [Source type: Academic]

.If the number of repeating units is unknown or variable, the letter n may be used to indicate this formula: CH3(CH2)nCH3.^ Polymers are indicated with the molecular formula of the repeating unit(s) in parentheses to which is appended an "x".
  • C471 Lecture: Chemical Name and Formula Searching 6 February 2010 10:52 UTC www.indiana.edu [Source type: Reference]

^ The number of atoms (if greater than one) is indicated as a subscript (although 19th-century books often used superscripts).

^ The Fake Greek Prefixes (FGPs above in the chart) are used to indicate the number.
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Ions

.For ions, the charge on a particular atom may be denoted with a right-hand superscript.^ The valence of an atom is the likely charge it will take on as an ion.
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^ When a molecule of a substance contains atoms of both metals and nonmetals, the electrons are more strongly attracted to the nonmetals, which become negatively charged ions; the metals become positively charged ions.
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^ This condition with the lowest number of formal charges and the right number of orbitals around each atom is the most stable and the most likely correct Lewis structure.
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.For example Na+, or Cu2+.^ Examples: Na + + Cl - --> NaCl sodium + chloride --> sodium chloride Cu 2+ + SO 4 2- --> CuSO 4 copper(II) + sulfate --> copper(II) sulfate Al 3+ + 3NO 3 - --> Al(NO 3 ) 3 aluminum + nitrate --> aluminum nitrate Arrangement of Atoms .
  • Chemical Nomenclature 6 February 2010 10:52 UTC www.shodor.org [Source type: Reference]

^ For example Na + , or Cu 2+ .
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  • Chemical formula: Encyclopedia of chemistry, analytics & pharmaceutics with 64,557 entries. 6 February 2010 10:52 UTC www.chemie.de [Source type: Reference]
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.The total charge on a charged molecule or a polyatomic ion may also be shown in this way.^ The only thing new is that the charge on the polyatomic ion pertains to the ion as a whole before a subscript is written.

^ When a molecule of a substance contains atoms of both metals and nonmetals, the electrons are more strongly attracted to the nonmetals, which become negatively charged ions; the metals become positively charged ions.
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^ Other metal ions that take different charges at different times can be named in the same way.
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.For example: hydronium, H3O+ or sulfate, SO42-.^ For example: hydronium, H 3 O + or sulfate, SO 4 2- .
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.For more complex ions, brackets [ ] are often used to enclose the ionic formula, as in [B12H12]2-.^ More complex formulas .
  • Working with chemical formulas 6 February 2010 10:52 UTC www.chem1.com [Source type: Reference]

^ Symbols for the elements may be used merely as abbreviations for the name of the element, but they are used more commonly in formulas and equations to represent a fixed relative quantity of the element.
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^ The second element in the formula only uses the first half of the word and -ide is added to the end, much like binary ionic compounds.
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.Parentheses ( ) can be nested inside brackets to indicate a repeating unit, as in [Co(NH3)6]3+.^ Polymers are indicated with the molecular formula of the repeating unit(s) in parentheses to which is appended an "x".
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^ The "x" indicates a repeating unit.
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Here (NH3)6 indicates that the ion contains six NH3 groups, and [ ] encloses the entire formula of the ion with charge +3.

Isotopes

.Although isotopes are more relevant to nuclear chemistry or stable isotope chemistry than to conventional chemistry, different isotopes may be indicated with a left-hand superscript in a chemical formula.^ A chemical formula in the Hill System may have more than one substance with that formula.
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^ Isotopes will have differing nuclear qualities.

^ The number of atoms (if greater than one) is indicated as a subscript (although 19th-century books often used superscripts).

.For example, the phosphate ion containing radioactive phosphorus-32 is 32PO43-.^ For example, the phosphate ion containing radioactive phosphorus-32 is 32 PO 4 3- .
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^ (For example: PO 4 3- phosphate; H 2 PO 4 1- dihydrogen phosphate) Now use this acid salt polyatomic ion as you would any other polyatomic ion in writing the formula of the compound listed .
  • How to Write Chemical Formulas 6 February 2010 10:52 UTC www.woodrow.org [Source type: Reference]

^ Cu has a 2+ charge & PO 4 has a 3- charge, so 3 copper (II) ions are required for every two phosphate ions.
  • Chemical Names and Formulas 6 February 2010 10:52 UTC www.slideshare.net [Source type: Reference]

Also a study involving stable isotope ratios might include the molecule 18O16O.
.A left-hand subscript is sometimes used redundantly to indicate the atomic number.^ Use subscripts to indicate the number of atoms of each element present.
  • Lesson 5-3 Writing Chemical Formulas 6 February 2010 10:52 UTC www.fordhamprep.org [Source type: Reference]

^ Rule 2: Use subscripts to indicate the number of atoms of each element in the compound.

^ The number of atoms (if greater than one) is indicated as a subscript (although 19th-century books often used superscripts).

For example, 8O2 for dioxygen, and 168O2 for the most abundant isotopic species of dioxygen. .This is convenient when writing equations for nuclear reactions, in order to show the balance of charge more clearly.^ Write balanced chemical equations for these two reactions.

^ Write the balanced chemical equation.
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^ Write a balanced chemical equation for the reaction.
  • Chemical Reactions - CK12 - Flexbooks 6 February 2010 10:52 UTC authors.ck12.org [Source type: Reference]

Empirical formulas

.In chemistry, the empirical formula of a chemical is a simple expression of the relative number of each type of atom or ratio of the elements in the compound.^ A formula represents the relative numbers of atoms of each element in a substance.
  • Atom element molecule compounds pure impure mixture, meaning definitions physical change, evidence chemical change 6 February 2010 10:52 UTC www.docbrown.info [Source type: Reference]

^ Subscripts represent numbers of atoms of each type of element.

^ Since the formula of a compound expresses the ratio of the numbers of its constituent atoms, a formula also conveys information about the relative masses of the elements it contains.
  • Working with chemical formulas 6 February 2010 10:52 UTC www.chem1.com [Source type: Reference]

.Empirical formulas are the standard for ionic compounds, such as CaCl2, and for macromolecules, such as SiO2.^ Empirical formulas are the standard for ionic compounds, such as CaCl2, and for macromolecules, such as SiO2.

^ Names and Formulas of Some Ionic Compounds Table 2-3 displays the formulas, charges, and names of some common ions  .
  • Chapter 02 Chemical Formulas & Composition Stoichiometry 6 February 2010 10:52 UTC www.scribd.com [Source type: Academic]

^ The second element in the formula only uses the first half of the word and -ide is added to the end, much like binary ionic compounds.
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.An empirical formula makes no reference to isomerism, structure, or absolute number of atoms.^ Empirical Formula The empirical formula is the simplest whole-number ratio of atoms in the compound.

^ An empirical formula makes no reference to isomerism , structure, or absolute number of atoms.
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  • Chemical formula - Hwiki 6 February 2010 10:52 UTC hwiki.fzk.de [Source type: Reference]
  • Chemical formula: Encyclopedia of chemistry, analytics & pharmaceutics with 64,557 entries. 6 February 2010 10:52 UTC www.chemie.de [Source type: Reference]

^ The subscript numbers in an empirical formula should have no common divisor.

.The term empirical refers to the process of elemental analysis, a technique of analytical chemistry used to determine the relative percent composition of a pure chemical substance by element.^ From pure substances to substance classes: chemical similarity .
  • HYLE 4-2 (1998): The Chemical Core of Chemistry I: A Conceptual Approach 6 February 2010 10:52 UTC www.hyle.org [Source type: FILTERED WITH BAYES]

^ Can you determine the molecular formula of a substance from its percent composition?

^ Chemical Formulas Chemical formula shows the chemical composition of the substance.
  • Chapter 02 Chemical Formulas & Composition Stoichiometry 6 February 2010 10:52 UTC www.scribd.com [Source type: Academic]

.For example hexane has a molecular formula of C6H14, or structurally CH3CH2CH2CH2CH2CH3, implying that it has a chain structure of 6 carbon atoms, and 14 hydrogen atoms.^ For example, the molecular formula for formaldehyde is CH 2 O. The molecular weight of formaldehyde is therefore .

^ Find the longest continuous chain of carbon atoms in the skeleton structure.

^ Encyclopedia - Chemical formula A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound.

.However, the empirical formula for hexane is C3H7.^ However, formulas that show the simplest possible atomic ratios must be assumed to be empirical unless evidence exists to the contrary.
  • Chemical Reaction - a knol by Admin 6 February 2010 10:52 UTC knol.google.com [Source type: FILTERED WITH BAYES]

.Likewise the empirical formula for hydrogen peroxide, H2O2, is simply HO expressing the 1:1 ratio of component elements.^ Is the first element in te formula hydrogen?

^ For this example, this is the lowest ratio, the Empirical formula.

^ H 2 O 2 is the formula for hydrogen peroxide.
  • CHEMTUTOR COMPOUNDS 6 February 2010 10:52 UTC www.chemtutor.com [Source type: FILTERED WITH BAYES]

.Formaldehyde and acetic acid have the same empirical formula, CH2O.^ If we wanted to know the percentage of formaldehyde, CH 2 O, whose formula weight is 30.0 amu we proceed as follows: .

^ Encyclopedia - Acetyl Acetyl (IUPAC name ethanoyl) is the acyl of acetic acid, with chemical formula -COCH3, sometimes abbreviated to Ac (not to be confused with the element actinium).

^ For example, the molecular formula for formaldehyde is CH 2 O. The molecular weight of formaldehyde is therefore .

.This is the actual chemical formula for formaldehyde, but acetic acid has double the number of atoms.^ "What is the chemical formula for ascorbic acid?"
  • what is the chemical formula from 30g of NaOH and 100ml of 40% ethanol 6 February 2010 10:52 UTC askville.amazon.com [Source type: General]

^ Encyclopedia - Chemical formula A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound.

^ Every chemical element consists of atoms the weights of which vary because of varying numbers of neutrons in their nuclei.
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  • CHEMICAL REACTION, 6 February 2010 10:52 UTC www.history.com [Source type: FILTERED WITH BAYES]

Trapped atoms

.The @ symbol ("at") indicates an atom or molecule trapped inside a cage but not chemically bound to it.^ If a molecule contains more than one atom of a particular element, this quantity is indicated using a subscript after the chemical symbol (although 19th-century books often used superscripts).
  • what is the chemical formula from 30g of NaOH and 100ml of 40% ethanol 6 February 2010 10:52 UTC askville.amazon.com [Source type: General]

^ A chemical formula is a shorthand way of using symbols of atoms to identify   molecule.

^ In more formal chemical use, an element symbol can also stand for one atom, or, depending on the context, for one mole ( Avogadro's number ) of atoms of the element.
  • Working with chemical formulas 6 February 2010 10:52 UTC www.chem1.com [Source type: Reference]

.This notation became popular in the 1990s with the discovery of fullerene cages, which can trap atoms such as La to form La@C60 or La@C82 for example.^ Hydrogen typically shares its single electron with one electron from another atom to form a single bond, such as in hydrogen chloride, H—Cl.
  • CHEMICAL REACTION, 6 February 2010 10:52 UTC www.history.com [Source type: FILTERED WITH BAYES]

^ The strength of C C single bonds and the covalent bonds carbon forms to other nonmetals, such as N, O, P, and S. The ability of carbon to form multiple bonds to other nonmetals, including C, N, O, P, and S atoms.

.A non-fullerene example is [As@Ni12As20]3-, an ion in which one As atom is trapped in a cage formed by the other 32 atoms.^ Therefore, Atoms, ions or molecules react with each other to become electronically more stable .
  • Atom element molecule compounds pure impure mixture, meaning definitions physical change, evidence chemical change 6 February 2010 10:52 UTC www.docbrown.info [Source type: Reference]

^ Eventually you will recognize the name of a polyatomic ion, but for now if you can't find an ion on one table, look on the other.
  • Lesson 5-3 Writing Chemical Formulas 6 February 2010 10:52 UTC www.fordhamprep.org [Source type: Reference]

^ One hydrogen atom has to be removed from each end of the hydrocarbon chain to form the C C bond that closes the ring.

Non-stoichiometric formulas

.Chemical formulas most often use integers for each element.^ Chemical structure can be represented using a structural formula.

^ If a molecule contains more than one atom of a particular element, this quantity is indicated using a subscript after the chemical symbol (although 19th-century books often used superscripts).
  • what is the chemical formula from 30g of NaOH and 100ml of 40% ethanol 6 February 2010 10:52 UTC askville.amazon.com [Source type: General]

^ Its chemical formula is C2HCl3O · H2O. It is used for the short-term treatment of insomnia and as a sedative before minor medical or dental tr ...

.However, there is a whole class of compounds, called non-stoichiometric compounds, that cannot be represented by small integers.^ Compounds of a metal and non-metal are commonly called __________ compounds.
  • Chemical Names and Formulas 6 February 2010 10:52 UTC www.hse.k12.in.us [Source type: Reference]

^ There are a small number of ionic compounds that do not fit into the system for one reason or other.
  • CHEMTUTOR COMPOUNDS 6 February 2010 10:52 UTC www.chemtutor.com [Source type: FILTERED WITH BAYES]

^ Sometimes, however, we have to do some work before using the coefficients of the terms to represent the relative number of molecules of each compound.
  • Stoichiometry 6 February 2010 10:52 UTC www.shodor.org [Source type: Academic]

Such a formula might be written using decimal fractions, as in Fe0.95O, or it might include a variable part represented by a letter, as in Fe1–xO, where x is normally much less than 1.

General forms for organic compounds

.Chemical formula used for a series of compounds that differ from each other by a constant unit is called general formula.^ Understand chemical formulas and the different representations of the chemical formula.

^ Chemical structure can be represented using a structural formula.

^ Chemical formula is a symbolized representation of a chemical compound.
  • CHEMICAL | Engineering-civil,mechanical,architectural,structural,aerospace... 6 February 2010 10:52 UTC eng2all.com [Source type: Reference]

Such a series is called the homologous series, while its members are called homologs.

Hill System

.The Hill system is a system of writing chemical formulas such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then the number of all other chemical elements subsequently, in alphabetical order.^ Write all the atoms in the material in the form of the formula of the compound.
  • CHEMTUTOR COMPOUNDS 6 February 2010 10:52 UTC www.chemtutor.com [Source type: FILTERED WITH BAYES]

^ A formula represents the relative numbers of atoms of each element in a substance.
  • Atom element molecule compounds pure impure mixture, meaning definitions physical change, evidence chemical change 6 February 2010 10:52 UTC www.docbrown.info [Source type: Reference]

^ All other prefixes WILL BE placed on the first element in the compound name.

.When the formula contains no carbon, all the elements, including hydrogen, are listed alphabetically.^ Is the first element in te formula hydrogen?

^ Compounds containing hydrogen and carbon.
  • Chemical Reactions - CK12 - Flexbooks 6 February 2010 10:52 UTC authors.ck12.org [Source type: Reference]

^ The list of formulas (above) are examples of elements that exist in nature as ___________________ molecules.

This deterministic system enables straightforward sorting and searching of compounds.

See also

References

  • Ralph S. Petrucci, William S. Harwood and F. Geoffrey Herring, General Chemistry, 8th Edition (Prentice-Hall 2002), chapter 3.

Citable sentences

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