Chapter 5 - "Ionic and Covalent Compounds"

Compound

A substance composted of two or more elements combined in a specific ration and held together by chemical bonds

ex: water and sodium

Valence Electrons

when atoms form compounds their valence electrons actually interact

Lewis dot symbol

consists of the element's symbol with dots representing valence electrons

Ionic bonding

referes to the electrostatic attraction that holds oppositely charged ions together in an ionic compound

Chemical Formula

an ionic compound denotes the constituent elements and the ratio in which they combine

Lattice

A three-dimensional array of oppositely-charged ions

Lattice Energy

the amount of energy required to convert a mole of ionic solid to its constituent ions in the gas phase

Depends on the magnitudes of the charge and distance between them

Magnitude of Lattice Energy

measure of an ionic compound's stability

Monatomic Cation

named by adding the word "ion" to the name of the element

K+ is potassium ion

Monatomic Anion

named by changing the ending of the elements name to "-ide"

Cl- is choride

O2 - is oxide

Exceptions of more than one possible charge:

Fe2+: Ferrous ion [Fe(II)]

Fe3+: Ferric ion [Fe(III)]

Mg2+: Manganese (II) ion

Mn3+: Manganese (III) ion

Mn4+: Manganese (IV) ion

Lewis Theory of Bonding

When compounds form between elements with their similar properties are not transferred from one element but instead shared in order to give each atom a noble gas configuration

H + H --> H:H

Covalent bonding

Where two atoms share a pair of electrons

Covalent bond

The shared pair of electrons constitute a covalent bond

Molecule

combination of at least two atoms in a specific arrangement held together by chemical forces (chemical bond)

Can be an element or compound

Law of definite proportions

different samples of a given compound always contain the same elements in the same ration

Law of multiple proportions

When two elements can form two or more "different" compounds

tells us that the ratio of masses of one element that combine with a fixed mass of the other element can be expressed in small whole numbers

Empirical Formula

Smallest Whole number ratio

Diatomic Molecules

contain two atoms and may be either heteronucleuar or homonuclear

Polyatomic molecules

contain more than two atoms

Molecular formula

shows the exact number of atoms of each element in a molecule

(True formula)

Allotropes

some elements have two or more distinct forms

Oxygen (O2)

Ozone (O3)

Structural formula

Shows not only the elemental composition but also the general arrangements

Binary Molecular compounds

substances that consist of just two different elements

Nomenclature

1.) Name first element that appears in formula

2.) Name the second element that appears in the formula, changing its ending to "-ide"

B2H6

Diborane

SiH4

Silane

NH3

Ammonia

PH3

Phosphine

H2O

Water

H2S

Hydrogen Sulfide

Polyatomic ions

consists of a combination of two or more atoms

Oxoacids

when dissolved in water, produce hydrogen ions and corresponding oxoanions

Can be monoprotic (one oionizable hydrogen) or polyprotic (more than one ionizable hydrogen)

Acid Based on -ate

ic acid

Acid Based on -ite

ous acid

hydrate

compound that has a specific number of water molecules within its solid structure

coper(II) sulfate has five water molecules

Molecular mass

mass in atomic mass units (amu) of an individual molecule

atomic mass # of atoms + atomic mass #of atoms = molecular mass

Molecular weight

atomic masses on periodic table are average masses, the result of such a determination is an average molecular mass

Percent composition by mass

a list of the percent by mass of each element in a compound