Understanding Chemical Bonds and Compounds

Inter

prefix meaning 'between' or 'among'

Intra

prefix meaning 'within'

Inter

prefix meaning 'between' or 'among'

Intra

prefix meaning 'within'

Intermolecular forces

Forces between different substances

Intramolecular forces

Forces within a substance (chemical bonds)

Chemical bond

a force/mutual electrical attraction that holds atoms together in a substance

Electronegativity

measure of the ability of an atom in a bond to attract electrons

Covalent bond

bond that results between nonmetallic elements that share electrons, forming a molecule

Molecule

compound formed when 2 or more elements are covalently bonded

Octet Rule

Atoms will gain, lose, or share electrons in order to have 8 electrons in their outer energy shell

Covalent compounds

Made up of nonmetals sharing electrons

Ionic bonds

when atoms transfer electrons in order to be stable

Binary ionic compound

when only made from 1 kind of metal atom and 1 kind of nonmetal

Ionic compounds

made of positive and negative ions that chemically bond in a way that the charges equal out

Cations

positively charged ions from losing electrons (typically metals)

Anions

negatively charged ions from gaining electrons (typically nonmetals)

Chemical formula

used to tell what elements and how many of each element are in a unit of a compound

NaCl

sodium chloride

Properties of covalent compounds

Molecules that can be solid, liquid, or gas; low melting and boiling points; cannot conduct electricity when dissolved in water

Properties of ionic compounds

Crystalline solids; high melting and boiling points; can conduct electricity when dissolved in water

Crystal lattice

network of cations and anions that are mutually attracted to one another

Stability

full/complete outer energy level of valence electrons

Electronegativity

ability of an atom to attract e- in a bond

Ions

Elements in the same group have the same number of valence e-

Oxidation Numbers

the charge of an ion within a compound

Group 1 elements

have 1 valence e- à 1+ charge

Group 2 elements

have 2 valence e- à 2+ charge

Group 13 elements

have 3 valence e- à 3+ charge

Group 14 elements

have 4 valence e- à 4+/- charge

Group 15 elements

have 5 valence e- à 3- charge

Group 16 elements

have 6 valence e- à 2- charge

Group 17 elements

have 7 valence e- à 1- charge

Rule of Zero Charge

The charges of metal cations and nonmetal anions should always add up to zero.

Nomenclature

All compounds have chemical formulas and names.

Binary ionic compounds

Compounds made of 2 elements that transfer e- in an ionic bond

Polyatomic ion

a charged group of covalently bonded atoms

Binary molecular compounds

Compounds made of 2 elements that share e- in a covalent bond

Exceptions for Ionic Rules

Transition metals: metals that can form many different ions

Transition Metals

metals that can form many different ions

Roman Numeral

used to show the charge of a transition metal

Naming Ionic Compounds

Name the cation (metal) and the anion (nonmetal) with an -ide ending.

Writing Chemical Formulas for Ionic Compounds

Write down the ions with their charges and determine the number of each ion needed to follow the rule of zero charge.

Helpful Hints for Ionic Compounds

When determining the Roman numeral for a transitional metal, try to reverse crisscross first.

Polyatomic ions protection

Always put parentheses around polyatomic ions to remember to 'protect' them.