Chemical Bonding. Unions That Build

8/14/2019 Chemical Bonding. Unions That Build

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ChemicalBonding.

Unions that build


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Atoms tend to gain, lose or share electrons

so as to have eight electrons in their outerelectron shell giving them the sameelectronic configuration as a noble gas.

The rule is applicable to the main-groupelements, especially carbon, nitrogen,oxygen, and the halogens, but also tometals such as sodium or magnesium.

In simple terms, molecules or ions tend tobe most stable when the outermostelectron shells of their constituent atomscontain eight electrons.
http://en.wikipedia.org/wiki/Noble_gashttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Halogenshttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Halogenshttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Noble_gas


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The octet rule does not work for predicting thecharges on transition metals ions.

Transition metals are located on the periodictable in the ten columns between columns forthe representative elements, and the groups arelabeled IB to VIIIB.

The transition metals typically produce ions with1+, 2+, 3+ and sometime 4+ charges, andunlike the representative elements manytransition metals can have more than onecharge state


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Valence electrons: Electrons in the outermostelectron shells, maximum 8 electrons. noble gaseshas 8 electrons

Ion: A charged atom. Can be either positive ornegative.

Positive ion: Is an atom that lost at least one electron,are called cations. Example Na+, Mg2+ , Al3+

Negative ion: Is an atom that gained at least oneelectron, are called anions. Cl-, O2- , N3-


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Groups IA, IIA, and IIIA have metallic atomsthat tend to lose electrons to acquireelectronic configuration of a noble gasforming positive ions.

Groups VA, VIA, VIIA have non metallicatoms that tend to gain electrons to

acquire electronic configuration of a noblegas forming negative ions.


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Element Group Valence e- Electrons toform Ion

IonForme

dLost Gained

Sodium IA Na+

Magnesium IIA Mg2+

Calcium IIA Ca2+

Aluminum IIIA Al3+

Sulfur VIA S2-

Oxygen VIA O2-

Chlorine VIIA Cl-

Bromine VIIA Br-


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Lewis structures, also called Lewis-dotdiagrams, Electron-dot diagrams orElectron-dot structures, are diagramsthat show the bonding between atoms of a

molecule, and the lone pairs of electronsthat may exist in the molecule.

Consists of the element symbol surrounded

by "dots" to represent the number ofelectrons in the outer energy level(correlated by the Group number).


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However, because of the high chargethat would result, either C4+ or C4- forcarbon and Si4+ or Si4- for silicon


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Lithium Calcium Aluminum Carbon

Nitrogen Oxygen Chlorine Argon

Lithium ion Calcium ion Aluminum ion Carbon

Nitrogen ion Oxygen ion Chlorine ion Argon


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Symbol AtomicElectronic

configuration

Lewisatom

structure

Formedion

Ionic Electronicconfiguration

Lewisionic

structure

Li 1s2 2s1 Li Li+ 1s2 Li+

BeB

C

N

O

F

Ne


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A chemical bond is the attraction caused bythe electromagnetic force between opposingcharges, either between electrons and nucleior as the result of a dipole attraction.

The strength of bonds varies considerably;there are "strong bonds" such as covalent orionic bondsand "weak bonds" such asdipole-dipole interactions, the

London dispersion force andhydrogen bonding.
http://en.wikipedia.org/wiki/Covalent_bondhttp://en.wikipedia.org/wiki/Ionic_bondhttp://en.wikipedia.org/wiki/Intermolecular_forcehttp://en.wikipedia.org/wiki/London_dispersion_forcehttp://en.wikipedia.org/wiki/Hydrogen_bondinghttp://en.wikipedia.org/wiki/Hydrogen_bondinghttp://en.wikipedia.org/wiki/London_dispersion_forcehttp://en.wikipedia.org/wiki/Intermolecular_forcehttp://en.wikipedia.org/wiki/Ionic_bondhttp://en.wikipedia.org/wiki/Covalent_bond


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Type of chemical bond that involves a metal and a

nonmetalion through electrostatic attraction. It is abond formed by the attraction between twooppositely charged ions, The electrostaticattraction between the oppositely charged ionscauses them to come together and form a bond

like magnets .

The metal donates one or more electrons, forminga positively charged ion or cation with a stableelectron configuration. These electrons then enterthe non metal, causing it to form a negativelycharged ion or anion which also has a stableelectron configuration.
http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Nonmetalhttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Electrostatichttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Electron_configurationhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Electron_configurationhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Electrostatichttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Nonmetalhttp://en.wikipedia.org/wiki/Metal


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For example, common salt is sodium chloride.When sodium (Na) and chlorine (Cl) are combined,the sodium atoms each lose an electron forming acation (Na+), and the chlorine atom gain an electronto form an anion (Cl).

Na + Cl Na+ + Cl-


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Formed between a metallic element and a nonmetallic element.

The bonding involves electrons transfer, themetal atom donates electrons while the non

metal accept the electrons.The compounds formed are solids with a crystal

lattice tridimensional structure. Most of them dissolve in water giving solutions

that conducts electricity Salts (NaCl) and acids (HCl) are ionic

compounds


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1. Find the total number of electrons:For each atom, read the group number.

2. Draw a first tentative structure:The element with the least number of atoms is usually thecentral element. Draw a tentative molecular and electronarrangement attaching other atoms with single bonds as thefirst guess.

3. Add electrons as dots to get octets around atoms:When counting electrons for the octet around an atom, countboth electrons in a bond for each atom and any lone pairelectrons. Hydrogen, of course, gets only 2 electrons.

4. Count the total number of electrons in the finalstructure to see if the total agrees with the number tabulated

in step #1. If not, then move a lone pair of electrons into adouble bond. Or add more lone pairs of electrons.

5. Cycle through steps 3 and 4 several times until you getit right by trial and error.


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NaCl Na IA = 1e Cl VIIA= 7e

Na + Na+

MgCl2 Mg IIA=2e Cl VIIA= 7e

Mg + Mg2+

RbBr

CaBr2AlF3SrO

Cl

Cl -

Cl

Cl

Cl -

Cl -


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Chemical bonding is characterized by thesharing of pairs of electrons between atoms.

Is formed by at least two non-metallic elements,

they can be molecules of the same atom like O2or different atoms like H2O.

The atoms can share more than one pair ofelectrons, they can share two or even three pairof electrons, like single, double or triple bonds.


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or

The pair of sharedelectrons can be drawnwith lines

Cl

Chlorine molecule Cl2

Cl = 7 e

Cl

pair of shared electrons inred, each chlorine atomhas 8 e


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Single: One pair of electrons are shared.

Double: Two pairs of electrons are shared.

Triple: Three pairs of electrons are shared

or


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1. Write the valence electrons of theNitrogen atom

2. Write the total number of electrons fromboth atoms

3. Draw the dot diagram

4. Arrange the electrons using octet rule(both atoms must have 8 electrons how

many electrons must they share?)


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N from family VA= 5 electrons

For the molecule N2 are 10 electrons

Sharing just one pair doesnt apply the octet rule.

Neither sharing two pairs of electrons apply

But sharing THREE pair of electrons the octet rule does apply

or N N

N

N

N

N

N

N

N

N


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F2

NH3

H2

H2S

HBr CH4

CO2 CO

O2

CCl4


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Polar covalent: between atoms of different elements. Example H2O,

H2

S, CO2

, CCl4.

The type of bond is also determined by the difference

of the electronegativity values of the elements


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Compound Electronegativityvalue of each atom

Electronegativity difference

Type of bond

F2 F: 4.0 F: 4.0 4.0 4.0 = 0 Covalent Non-polar

H2SNaF

RbBr

NH3

HF

MgO

KCl

N2

CH4


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In chemistry, polarity refers to a separation ofelectric charge leading to a molecule having anelectric dipole.

Polar: Is a molecule that can dissolve in waterlike Salts (NaCl, KF, etc) and Acids (HCl, HNO3,

etc).

Non polar: Is a molecule that can not dissolve inwater like fats, oils, gasoline, methane gas(CH4) carbon tetrachloride (CCl4), CO2.
http://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Dipolehttp://en.wikipedia.org/wiki/Dipolehttp://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Chemistry


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A water molecule, a commonly-used example

of polarity. The two charges are present witha negative charge in the middle (red shade),and a positive charge at the ends (blueshade).
http://en.wikipedia.org/wiki/Water_moleculehttp://en.wikipedia.org/wiki/Water_molecule


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Metallic bonding is the electromagnetic interaction

between delocalized electrons, called "electrons sea. The electrons sea are the responsible for the physical

properties of solid metals: conduct heat and electricity,generally high melting and boiling points,strong,

malleable (can be hammered or pressed out of shapewithout breaking), ductile (able to be drawn into a wire),metallic lustre

The elements involved in this type of bonding are mainlythe transition metals like Fe, Cu, Au, Ag, Al, Zn, Pt, etc.
http://en.wikipedia.org/wiki/Delocalized_electronhttp://en.wikipedia.org/wiki/Delocalized_electron


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Which of the

following pairs

has the

strongest

hydrogen bond.

a)HCl or HF

b)NH3 or PH3

c)H2O or H2S

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