Chapter 5.0 General Chemistry

percent composition by mass

A list of the percent by mass of each element in a compound. ex: %H= (2x1.008 amu H)/(34.02 amu H2O2) x 100= 5.926% %O =(2x16.00 amu O)/(34.02 amu H2O2) x 100 = 94.06%

Compound

A substance composed of two or more elements combined in a specific ratio and held together by chemical bonds. A compound cannot be separated into simpler substances by a physical process. Example of compound: H2O (water) , NaCl (Sodium Chloride)

Naming ionic compounds

An ionic compound is named using the name of the cation followed by the name of the anion, eliminating the word ion from each. Ex: Sodium Bromide (NaBr), calcium fluoride (CaF2), lithium nitride (Li3N), and sodium sulfide (Na2S)

molecular weight

Average molecular mass

Lewis dot symbol

Consists of the elements symbol surrounded by dots, where each dot represents a valence electron. For main group elements, the number of dots in the Lewis symbol is the same as the group number (transition metals are usually not represented with Lewis dot symbols because they have incomplete inner shells)

Monoprotic

Each has just one ionizable hydrogen atom.

Formula of ionic compound

H2O ratio: 2:1 H2O2 ratio: 1:1 or 2:2

law of multiple proportions

If two elements can combine with each other to form two or more different compounds, the ratio of masses of one element that combine with a fixed mass of the other element can be expressed in small whole numbers.

Naming ionic compound metals

In cases where a metal cation may have more than one possible charge, recall that the charge is indicated in the name of the ion with a Roman numeral in parentheses. Thus, the compounds FeCl2, and FeCl3 are named iron (II) chloride and iron (III) chloride. ("Iron-two chloride", "Iron-three chloride")

Naming monatomic ion (anion)

Is named by changing the ending of the elements name to -ide, and adding the word ion. Thus, the anion of chloride, Cl-, is called chloride ion. The anions of carbon, nitrogen, and oxygen (C4-, N3-, and O2-) are called carbide, nitride, and oxide. (NOTICE HOW ALL OF THESE ARE ELECTROSTATIC TO A NOBLE GAS)

Interconverting mass, moles, and numbers of particles

Molar mass is the conversion factor that we use to convert from mass (m) to moles (n), and vice versa. We use Avogadro's number (6.022 x 10^23) to convert from number of moles to number of particles (N) and vice versa.

Naming monatomic ions (cation)

Monatomic cation is named by simply adding the word ion to the name of the element. Thus the ion of potassium, K+, is known s potassium ion. It is not necessary to specify the charges on these ions because their charges are equal to their group numbers.

ionizable hydrogen atom

One that separates from the molecule upon dissolving and becomes a hydrogen ion, H+

Joseph Proust

Proposed law of definite proportions

Gilbert Lewis

Suggested that a chemical bond involves atoms sharing electrons

molecule

The formation of a covalent bond between two H atoms. A molecule is a neutral combination of atleast two atoms in a specific arrangement held together by chemical bonds. A molecule may contain two or more atoms of a single element, or it may contain atoms of two or more elements joined in a fixed ratio.

empirical formula mass

The same thing as percent composition except you can simplify the compound. So H2O2 can be HO in the empirical formula. ex: (The amu of H2O2 is actually of HO) %H = (1.008 amu H)/(17.01 amu H2O2) x 100 = 5.926% %O =(16.00 amu O)/(17.01 amu H2O2) x 100 = 94.06%

lattice

The structure of an ionic compound consists of a vast array of interspersed cation and anions

Ionic compound

When cation and anions are brought together.

Naming with Hydrogen

When naming with hydrogen, you take out the "-gen" part of Hydrogen. So HCl would be Hydrochloric acid

Writing Lewis dot structures

When writing dot structures, each side can have a maximum two dots and you can not put two dots on one side unless all of the other sides have a dot.

hydrate

a compound that has a specific number of water molecules within its solid structure. Ex: In its normal state, for example, each unit of copper(II) sulfate has five water molecules associated with it. The systematic name for this compound is copper (II) sulfate pentahydrate, CuSO4 5H2O. The water molecules can be driven off by heating. When this occurs, the resulting compound is CuSO4, anhydrous copper(II) sulfate.

homonuclear

both atoms in each molecule are the same element. homonuclear diatomic molecules (examples below) ex: I2, C2, H2

hydrocarbons

compounds that only contain hydrogen and carbon ex: CH4 = methane C2H6 = Ethane C3H8 = Propane

Monatomic ions

consists of a single atom with more electrons than protons, in the case of an anion, or fewer electrons than protons, in the case of a cation.

organic compound

contain carbon and hydrogen

heteronuclear

contain different elements. ex: HCl and CO

diatomic molecule

contains two atoms (hence the prefix di-) ex: H2

Chemical formula

denotes the constituent elements of the compound and the ratio in which they combine.

Functional group

determines many of the chemical properties of a compound because it typically is where a chemical reaction occurs.

law of definite proportions

different samples of a given compound always contain the same elements in the same mass ratio.

inorganic compound

do not contain carbon

covalent bond

each electron in a shared pair is attracted to the nuclei of both atoms. It is the attraction that holds the two atoms together.

ionic bonding

electrostatic attraction between oppositely charged particles. Example: when chlorine atoms come in contact with sodium atoms, the valence electron of sodium is transferred to the chlorine atom.

Polyatomic molecules

molecules containing more than two atoms.

allotrope

one of two or more distinct forms of an element. ex: O = O2, O3 C = C2, C3

Oxoanions

polyatomic anions that contain one or more oxygen atoms and one atom of another element. ex: chlorate

Structural formula

shows not only the elemental composition but also the general arrangement of atoms within the molecule. Structural formula of water: HOH

molecular formula

shows the exact number of atoms of each element in a molecule. ex: H2O2 ratio: 2:2 (it does not simplify) gives you the full thing. ex: C6H12O6

alkane

simplest example of alkanes. the name of the alkane depends on the number of carbon atoms in the molecule.

empirical formulas

simplified ratio and does not show all of the atoms. ex: N3H3, 3:3 = NH, 1:1 (you do not know how many nitrogen and hydrogen atoms there are based on that ratio) only gives ratios

acid

substance that produces hydrogen ions (H+) when dissolved in water. ex: HCl, hydrogen chloride, is a gaseous compounds. When it is dissolved in water, however, we call it hydrochloric acid. Take the "-gen" from hydrogen and change the "ide" to "ic"

binary compounds

substances that consist of just two different ions derived from two different elements, one metal and one nonmetal

lattice energy

the amount of energy required to convert a mole of ionic solid to its constituent ions in the gas phase. The magnitude of lattice energy is the measure of an ionic compounds stability. The greater the lattice energy, the more stable the compound. for example, the lattice energy of NaCl is 788 kJ/mol. Thus, it takes 788 kJ of energy to convert one mole of NaCl to one mole each of Na+ and Cl-. Lattice energy depends on the magnitudes of the charges and on the distance between them.

anhydrous

the compound has no water molecules associated with it.

molar mass

the mass in grams of one mole of the substance. ex: Atomic mass of calcium is 40.08 amu and its molar mass if 40.08 g Atomic mass of sodium is 22.99 amu and its molar mass is 22.99 g 1 g = 6.022 x 10^23 amu 1 amu = 1.661 x 10^-24 g

molecular mass

the mass of an individual molecule (in amu). The molecular mass is simply the sum of the atomic masses of the atoms that make up the molecule. ex: molecular mass of H2O 2(atomic mass of H) + atomic mass of O = 2(1.008 amu)+16.00 amu = 18.02 amu

Lewis theory of bonding

the theory that a chemical bond involves atoms sharing electrons. When compounds form between elements with similar properties, electrons are not transferred but are instead shared to give each atom a noble gas configuration.

Polyprotic

they have more than one ionizable hydrogen atom. ex: H2SO4

Naming transition metal ion (cation)

transition metals, can form cations of more than one possible charge. Iron for example can form Fe2+ or Fe3+. Assign the -ous to the smaller charge and the -ic to the cation with the greater charge. This is a little old though. It is more common to see it written like this: Mn2+: manganese (II) ion Mn3+: manganese (III) ion Mn4+: manganese (IV) ion These are pronounced "Manganese-two ion" "Manganese-three ion" "Manganese-four ion"

oxoacids

when dissolved in water, produce hydrogen ions and the corresponding oxoanions. The formula of an oxoacid can be determined by adding enough H+ ions to the corresponding guidelines: 1. an acid based on an -ate ion is called.... ic acid. Thus, HClO3 is called chloric acid 2. An acid based on an -ite ion is called.... ous acid. Thus HClO2 is called chlorous acid. 3. Prefixes in oxoanion names are retained in the names of the corresponding oxoacids. Thus, HClO4 and HClO are called perchloric acid and hypochlorous acid, respectively.