Excelsior Chemistry Unit 4

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Monatomic Ions
Consist of a single atom with a charge resulting from the loss or gain of electrons. Includes Cations, Anions, and Ions of Transition Metals.
Cations
When the metals in Groups 1A, 2A, and 3A lose electrons, they form cations with positive charges equal to their group number. To name a cation, you name the metal and put the word ion or cation afterwards.
Anions
Nonmetals tend to gain electrons to form anions, so the charge of a nonmetallic ion is negative. The charge of any ion of a Group A nonmetal is determined by subtracting 8 from the group number. To name an anion, it starts with the stem of the element name and ends with -ide.
Ions of Transition Metals
The charges of the cations of many transition metal ions must be determined from the number of electrons lost. To name a transition metal, there are two ways. The preferred way is the Stock system which uses Roman Numerals in parenthesis after the name of the element to indicate the numerical charge. The classical naming system uses the root word of each element and the ending -ous or -ic.
Polyatomic Ions
Composed of more than one atom. The names of most of these end in -ite or -ate. All anions with the names ending in -ite or -ate contain oxygen.
Naming Binary Ionic Compound
Binary compounds are composed of two elements and can be either ionic or molecular. To name any binary ionic compound, place the cation name first, followed by the anion name.
Writing formulas for Binary Ionic Compounds
If you know the name of the binary ionic compound, you can write the formula. Write the symbol of the cation and then the anion. Add whatever subscripts are needed to balance the charges.
Naming Compounds with Polyatomic Ions
To name a compound with a polyatomic ion, state the cation first and then the anion just like binary ionic compounds.
Writing the formulas for an ionic compounds with polyatomic ions
The same as for binary ionic compounds. You write the symbol for the cation followed by the formula for the polyatomic ion and balance the charges.
Naming Binary Molecular Compounds
Binary Molecular Compounds are composed to two elements, both nonmetals and they are not ions. The prefix in the name of a binary molecular compound tells how many atoms of an element are present in each molecule in the compound. Mono for 1, di for 2, tri for 3 and so on.
Writing Formulas for Binary Molecular Compounds
Use the prefixes in the name to tell you the subscript of each element in the formula. Then write the correct symbols for the two elements with the appropriate subscripts.
Acids
A group of ionic compounds that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water.
Naming Acids
The three rules for naming acids are:
1.) When the name of the anion ends in -ide, the acid begins with the prefix hydro-. The stem of the anion has the suffix -ic and is followed by the word acid.
2.) When the anion ends in -ite, the acid name is the stem of the anion with the suffix -ous followed by the word acid.
3.) When the anion ends in -ate, the acid name is the stem of the anion with the suffix -ic followed by the word acid.
Writing the formulas for acids
Use the rules for naming acids in reverse to write the formulas for acids.
Bases
A group of ionic compounds that produces hydroxide ions (OH-) when dissolved in water.
Naming bases
Bases are named the same way as other ionic compounds- the name of the cation followed by the name of the anion.
Writing the formula for bases
Write the symbol for the metal cation followed by the formula for the hydroxide ion, then balance the charges as you would for any ionic compound.
Naming Chemical Compounds Flowchart
Is the first Element Hydrogen? If yes, the compound is an acid.
If not, does it have more than two elements total? If yes, the compound contains a polyatomic ion and will usually end in -ite or -ate. If no, it is a binary compound and the name will end in -ide. Once you have determined that the compound contains a polyatomic ion, ask if the first element is in Group A. If yes, name the ions. If no, Name the ions using a Roman Numeral with the cation. If the compound does not have a polyatomic ion, and is therefore binary, ask if the first element is a metal. If not, the compound is binary molecular so use prefixes in the name. If it is metal, determine if the first element is in Group A. If yes, name the ions. If not, name the ions using a Roman Numeral with the cation.
-ide suffix
Generally indicates binary compounds
-ite or -ate suffixes
means polyatomic ions that include oxygen in the formula
Prefixes
Generally indicate that the compound is molecular
Roman Numerals
Shows the ionic charge of the cation
Moles
The unit that chemists use to help count the the representative particles in a substance. Similar to how a dozen is 12. A mole is always 6.02 x 10^(23).
Representative Particles
Refers to the species present in a substance and usually means atoms, molecules, or formula units. For most elements, it is the atom. For molecular compounds, it is the molecule. For ionic compounds, it is the formula unit.
Avogadro's Number
The number of representative particles in 1 mole of substance. Named in honor of the Italian scientist who clarified the difference between atoms and molecules.
What is a mole?
A mole of any substance contains Avogadro's number of representative particles, or 6.02 x 10^(23) representative particles.
Formula for moles from representative particles
To convert representative particles to moles, divide the representative particles by 6.02 x 10^(23).
Formula for representative particles from moles
To convert moles to representative particles, multiply the number of moles by 6.02 x 10^(23) times the number of atoms in a representative particle (determined from the chemical formula)
Molar Mass of an Element
The atomic mass of an element expressed in grams
Molar Mass of a Compound
Add the atomic masses of the all the atoms making up the molecule, then substituting the unit grams for atomic mass.
Mole-Mass Relationships
Use the conversion factor the molar mass = 1 mole. You will need to determine the molar mass of the substance fist. Then, if given the moles, then multiply the molar mass by the number of moles you require to get the mass you need. If you are given the mass in grams, divide it by the molar mass to determine how many moles.
STP
Standard Temperature and Pressure means a temperature of zero degrees Celsius and a pressure of 1 atmosphere or 101.3 kPa.
Molar Volume
At STP, 1 mol of representative particles or any gas occupies a volume of 22.4 L or molar volume of gas.
Mole-Volume Relationships
Use the conversion factor 22.4 L = 1 mol at STP. When given the moles of gas at STP, multiply it by 22.4 to get the L of volume. When given the liters of gas at STP, divide it by 22.4 to get the moles.
Calculating Molar Mass from Density
When given the density, multiply it by 22.4 to get the molar mass. If asked for the density, determine the molar mass, and divide by 22.4.
Percent Composition
The relative amounts of the elements in a compound. Consists of a percent value for each different element in the compound.
Percent Composition Formula from Mass
Divide the mass of the element, by the mass of the compound and then multiply by 100%.
Percent Composition Formula from Chemical Formula
Divide the mass of the element in 1 mol of compound by the molar mass of the compound and then multiply by 100%.
Empirical Formula
The basic ratio of the elements contained in a compound, which gives the smallest whole-number ratio of the atoms of the elements in the compound.
Determine the Empirical Formula
Take the % Composition and convert it to moles. Then, to make the subscripts whole numbers, divide each molar quantity by the smallest number of moles. If they are still not whole numbers, then multiply them by the same number to obtain a whole number.