Lesson 3 - Chemical Bonds

Gilbert N. Lewis

The one who came up with the octet rule

Octet Rule

When undergoing a chemical reaction, atoms of Group 1A-7A elements tend to gain, lose or share sufficient electrons to achieve an electron configuration having eight valence electrons.

Octet Rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

Anion

A negatively charged ion

Cation

A positively charged ion

Anion

gains electrons

Cation

loses electrons

Unchanged

When an ion forms, the number of protons and neutrons remains ________.

Changed

When an ion forms, the number of electrons in the valence shell _________.

Unstable

Ions of period 1A and 2A elements with charges greater than +2 are ________.

Transition Elements

The octet rule does not apply to what group of elements.

International Union of Pure and Applied Chemistry

The body responsible for the standardization of chemical nomenclature and usage

Monoatomic Cation

forms when a metal loses one or more valence electrons

Elements of Groups 1A, 2A and 3A form only one type of cation.

Hydrogen Ion

ION NOMENCLATURE

H+

Lithium Ion

ION NOMENCLATURE

Li+

Copper (I) Ion

ION NOMENCLATURE

Cu+

Copper (II) ion

ION NOMENCLATURE

Cu2+

Cuprous ion

ION NOMENCLATURE

Cu+ (Common Name)

Cupric Ion

ION NOMENCLATURE

Cu2+ (Common Name)

Hydride

ION NOMENCLATURE

H-

Iodide

ION NOMENCLATURE

I-

Oxide

ION NOMENCLATURE

O2-

Ammonium

ION NOMENCLATURE

NH4+

Hydrogen Carbonate

ION NOMENCLATURE

HCO3-

Ionic Bond

A chemical bond resulting from the attraction between positively and negatively ions.

Covalent Bond

A chemical bond resulting from the sharing of electrons between atoms. Commonly forms a Polyatomic Ion.

Ionic Bond

metal + nonmetal bond

Covalent Bond

nonmetal + nonmetal/metalloid bond

Electronegativity

It is a measure of an atom's attraction for the electrons it shares in a chemical bond with another atom.

Flourine

most electronegative element

Linus Pauling

Developed the electronegativity scale

Electronegativity

A measure how tightly an atom holds the electrons that it shares with other atom.

Ionization Energy

It measures the amount of energy necessary to remove an electron from an atom.

Binary Compound

a compound composed of two elements

Lithium Bromide

NOMENCLATURE

LiBr

Silver Sulfide

NOMENCLATURE

Ag2S

Sodium Bromide

NOMENCLATURE

NaBr

Copper (II) Oxide

NOMENCLATURE

CuO

CuO

FORMULA

Cupric Oxide

Copper (I) Oxide

NOMENCLATURE

Cu2O

Cu2O

FORMULA

Cuprous Oxide

NaNO3

FORMULA

Sodium nitrate

Ammonium Nitrate

NOMENCLATURE

NH4NO3

Single Bond

a covalent bond in which two atoms share one pair of electrons

Nonpolar Covalent Bond

Electronegativity less than 0.5

Polar Covalent

Electronegativity 0.5 to 1.9

Ionic Bond

Electronegativity greater than 1.0

Dipole

A chemical species in which separation of charge; there is positive pole in one part of the species and a negative pole in another part.

Delta Plus δ+

Less Electronegative Atom (Dipole)

Delta Minus δ-

More Electronegative Atom (Dipole)

Lewis Structure

A structural formula in which electrons are represented by dots; dot pairs or dashes between two atomic symbols represent pairs in covalent bonds.

Bonding Electrons

Valence electrons involved in forming a covalent bond (i.e., shared electrons).

Nonbonding Electrons

Valence electrons not involved in forming covalent bonds. Also called unshared pairs or lone pairs.

Double Bond

A chemical bond formed when atoms share two pairs of electrons

Triple Bond

A chemical bond formed when atoms share three pairs of electrons.

Binary Covalent Compounds

It is a two-element compound in which all bonds are covalent.

First

Rules in Binary Covalent Nomenclature

Less Electronegative Element is generally written ________ in the formula

-ide

Rules in Binary Covalent Nomenclature

The more electronegative element should a suffix ________ to its stem name.

di-, tri-, tetra-

Rules in Binary Covalent Nomenclature

Use the prefixes _______, to show the number of atoms in each element.

Nitrogen oxide / Nitric Oxide

BINARY COVALENT NOMENCLATURE

NO

Sulfur difluoride

BINARY COVALENT NOMENCLATURE

SF2

Dinitrogen Oxide / Nitrous Oxide

BINARY COVALENT NOMENCLATURE

N2O

Resonance

Theory that many molecules and ions are best described as a hybrid of two or more Lewis contributing structures.

Contributing Structure

representation of a molecule or ion that differ only in the distribution of valence electrons

also known as resonance structures or resonance contributors

Resonance Hybrid

a molecule or ion described as a composite or hybrid of a number of contributing structures

Double-headed arrows

symbols used to show that the structures on either side of it are resonance contributing structures

Bond Angle

The angle between two bonded atoms and a central atom

Valence Shell Electron Pair Repulsion (VSEPR) Theory

It is the molecular model to predict the geometry of the atoms making up a molecule where the electrostatic forces between a molecule's valence electrons are minimized around a central atom.