Chemistry Chapter 5

molecular compound/molecular bonding

-NONMETALS and NONMETALS or -METALS and METALS

Acids

-When dissolved in water, some compounds form acids EX: HCl (aq.) ---> hydrochloric acid (aq=aqueous) as compared to HCl (g) ---> hydrogen chloride (g=gas)

Polyatomic Ions to Acids

-add enough H+ ions to balance the corresponding oxoanions charge -if anion ends with "ite", the acid ends with "ous" acid -if anion ends with "ate", the acid ends with "ic" acid

molecular mass/formula mass

-aka "molecular weight" and "formula weight" -from molecular formula -use the atomic mass to get the molar mass: (# of each element) x (atomic mass) -then get the sum for each element

percent composition

-aka percent by mass -what percent of the total mass comes from each element -useful for determining empirical and molecular formulas -allows verification of purity of a sample -DETERMINED BY: dividing TOTAL MASS of each element in a compound by using the MOLECULAR MASS of the compound and multiplying by 100 % by mass of element = (n x atomic mass of element) / (molecular mass of the compound) x 100

How do you name a ionic compound with a cation that has only one charge?

-alkali metal cations -alkali earth metal cations -Ag(+), Al(3+), Cd(2+), Zn(2+) -name metal first -if it is a monoatomic ion, add -IDE to the root of the element name -if it is a polyatomic ion, use the name of the anion

homonuclear diatomic

-contains TWO of the SAME atom -EX: H2, N2, O2, F2, Cl2, Br2, I2

Lewis Dot Symbols

-displays valence electrons -useful for main group elements (NOT so much for transitional metals) -# of dot = group number = valence electrons -do not pair until NECESSARY -# of unpaired dots = # of bonds the atom can form -ions can ADD or REMOVE dots to reflect final valence (i.e. CATIONS - SUBTRACT electrons, ANIONS - ADD electrons)

Hydrates and how to name compounds

-have a specific number of waters in their structure -anhydro: indicates there is no water EX: CuSO4 ---> anhydrous copper (II) sulfate -name compound and add word hydrate to indicate the number of water molecules with prefixes EX: CuSO4 x 5H2O ---> copper sulfate pentahydrate

structural formula

-how atoms are CONNECTED together -EX1: HCOOH (H-C, O-H, and so on)

Relationship between Lattice Energy and Melting Point?

-larger lattice energy = higher melting point -strong forces hold crystals together -more energy is required to disrupt/breakdown the lattice

allotrope

-one of TWO OR MORE distinct forms of an element -EX1: diamond and graphite (both carbon) -EX2: molecular oxygen (O2) and ozone (O3)

How do you name a ionic compound with a cation that has more than one charge?

-other metal cations that ARE NOT alkali metal or alkali earth metals -name metal first -specify charge of metal cation with Roman numeral in parantheses -if monoatomic anion, add -IDE to the root of the element name -if polyatomic anion, use the name of the anion

molecular formula

-shows the EXACT # of atoms of EACH element in a molecule -subscripts indicate the # of atoms of each element present in formula -subscripts are WHOLE numbers

compounds

-substance with two or more elements -EX: H2O

empirical formula

-tells what elements are present in a molecule with the SIMPLEST WHOLE NUMBER RATIO -EX: H2O2 (molecular formula) ---> HO (empirical formula)

Lattice Energy

-the amount of energy required to completely convert one mole of a solid ionic compound to the constituent ions in the gas phase -LE = kQ1Q2/d^2 -k = 8.99e9 JmC^2 -Q1 and Q2 = charges -d = distance between ion centers

molecules

-two or more atoms held together by CHEMICAL BONDS -EX: H2

How do you name a molecular compound?

-use prefixes for BOTH elements present (mono- usually omitted for the first element) -add -IDE to the the root of the SECOND element

Ionic Compounds/Ionic Bonding

-usually between METALS and NONMETALS -formation of ionic compounds (CATIONS and ANIONS together) is VERY favorable

diatomic molecule

contains TWO atoms

homonuclear

contains the SAME atom

"-ic"

ending for HIGHER common charge

"-ous"

ending for LOWER common charge

Covalent bonds

gases, liquids, or solids with low melting point

Ionic bonds

usually solids

similarities between molecular and empirical formula of a compound

1. both are chemical formulas

empirical formula from percent composition steps

1. convert given amounts to moles 2. mole ratio (divide all moles by the smallest number of moles) --> #s represent the subscripts! 3. if #s are not whole numbers, multiply by some factor to make them whole

What makes Lattice Energy increase?

1. increase in charges (Q) - higher the charge, harder to pull apart 2. decrease in distance (d) - smaller the distance, harder to pull apart -increase in charge has larger effect on the LE than the distance because it is able to change faster

differences between molecular and empirical formula of a compound

1. molecular lists all the atoms in a molecule, while the empirical formula shows the simplest ratio of whole number of atoms in a molecule 2. empirical formulas are used to describe ionic compounds and macromolecules

difference between molecular mass and formula mass

1. molecular mass is used for molecules that are discrete (covalent compounds) 2. formula mass refers to the mass of the empirical formula of an ionic compound