Chap 5 Matter and Chemical Bonding

8/8/2019 Chap 5 Matter and Chemical Bonding

1/54

FOUNDATION INFOUNDATION IN SCIENCESCIENCEFOUNDATION INFOUNDATION IN SCIENCESCIENCE

NIRWANA ACADEMY GROUP OF COLLEGESNIRWANA ACADEMY GROUP OF COLLEGES

CHEMISTRY ACHEMISTRY A

CHAPTER 3CHAPTER 3

MATTER AND CHEMICALMATTER AND CHEMICAL

BONDINGBONDING

CHAPTER 3CHAPTER 3

MATTER AND CHEMICALMATTER AND CHEMICAL

BONDINGBONDING


2/54

CHM1001 CHEMSTRYACHAPTER 5: Matter and Chemical Bonding

LEARNING OUTCOMESLEARNING OUTCOMES

At the end of the lessons, student would beable to

understand the meaning of matter

distinguish between solid, liquid, gas andplasma

understand the physical changes of matter


3/54


NATURE OF MATTERNATURE OF MATTER


4/54


Three main matter: solid, liquid, gas

Another matter: plasma

Very depends on temperature; cause the

atoms, molecules or ions to move more activestate

Substance or compound still remain the same

When a substance exist as solid, liquid and gasat the same time (combination of all states),

the substance was to be in equilibrium state



5/54




6/54


Closely packed with fixed position

Less vibration

Have certain shape and arrange in the

form of crystal

High melting point due to strong attraction

SOLIDSOLID


7/54


Quite close, do not have an absolute shapebut follows the shape of container with

fixed volume

Moving around randomly and collisionoccur

Weaker attraction than solid but have

higher energyStronger force have higher boiling point

LIQUIDLIQUID


8/54


Far apart and also do not have an absoluteshape; filled up the space of the container

Freely and randomly move anywhere with

high velocities; random motionLess collision between particle and

container

Very low force of attraction

GASGAS


9/54


Partially ionized gas; free proportion ofelectrons

Charge of ions move independently;

electrically conductive where it can respondstrongly to electromagnetic field

Has unique properties

PLASMAPLASMA


10/54


Happens when reaches at a certain point

Melting point, boiling point, freezing point

Other factor which can influence: pressure

Physical changes and chemical changes

Physical changes: changes from one state toanother state

Chemical changes: changes of substance;involves certain process

CHANGES OF STATECHANGES OF STATE


11/54


PHYSICAL CHANGESPHYSICAL CHANGES


12/54


Gas was said to be a final state of matterSome substances exist as gas in room

temperature while other solid or liquid

substances would always converted to gasjust by heating at certain temperature

Ionic compounds only exist as solid andhardly to convert to gas unless when apply

an extremely high temperatureIt able to convert to liquid/molten state

but also with a high temperature

PROPERTIES OF GASPROPERTIES OF GAS


13/54


Thus most of the covalent substance moreeasily to convert to gas at low temperaturethan the ionic compound because of thestrength of the bonds formed

All gases would have the followingcharacteristics:The volume and shape are depend on the

container Easily to mix evenly and completely when

confined to the same container

Have the lowest density than the other state

PROPERTIES OF GASPROPERTIES OF GAS


14/54


A theory which introduced to define theproperties of gas

Some assumptions need to take note in order

to proceed to calculation Gas composed of molecules that are separated

from distances far to each other

Gas molecules are in constant motion in random

direction and collide to each other frequently. As aresult to this collision, energy can be transferred

from one molecule to another by maintaining the

total energy of the system

KINETIC MOLECULAR THEORYKINETIC MOLECULAR THEORY


15/54


Gas molecules exert neither attractive norrepulsive forces with one another

The movement of the gas molecules are fairly

depends on T, V of the container, P in the

container

The collisions between gas molecules and the

walls of their container produce gas pressure

The gas molecules will be more energeticwhen a higher T is apply

KINETIC MOLECULAR THEORYKINETIC MOLECULAR THEORY


16/54


Important units in calculation Pressure torr = 1mmHg; 1atm = 760mmHg/torr

1atm = 101,325 Pa / 1.01325105 Pa; Pa = pascals

= 1.0132510

2

kPa Temperature 0K = -273.15oC : absolute zero

0oC = 273.15K : Freezing point of water

100 oC = 373.15K : Boiling point of water

X oC = (X+273.15) K; sometime 273K was used

Volume Either liter, L or milliliter, mL

IDEAL GAS EQUATIONIDEAL GAS EQUATION


17/54


Boyles Law: V at constant n and T

Charles Law: V T at constant n and P

Avogadros Law: V n at constant P and T

Since all involve the relationship of V, theexpression can be combine as

V V=R

PV=nRT

where R is the gas constant. Thus STP, R would have the value of0.0821 L atm K-1 mol -1. If the unit ofP is change to Pa or torr thevalue would be 8.3145103 L Pa K-1 mol-1 and 62.3637 L torr K-1 mol-1

respectively.

IDEAL GAS EQUATIONIDEAL GAS EQUATION


18/54


formed between atoms due to the interactionof electrons

Tends to reach stability by fulfilling the

electrons in the valance shell with maximumnumbers of electrons; valance electrons

Have the ability to donate/lose electron,

receive electrons, share electron to form a

certain chemical bond

Form diatomic or polyatomic chemical

compound

CHEMICAL BONDINGCHEMICAL BONDING


19/54


Can classified as strong bonds and weakbond

Strong bond involve sharing or transfer ofelectrons

Weak bond involve forces of attraction

Two main type of strong chemicalbonding: ionic bonding, covalent bonding

Hydrogen bonds and Van der Waals bondare example of weak chemical bond

CHEMICAL BONDINGCHEMICAL BONDING


20/54


interaction between metal and non-metalto form a compound; electron transfer

Electron transfer forms ion; metal loses

electron form cation; non-metal gainelectron form anion

Attracted each other by electrostatic force

Non-metal with higher electronegativitytends to receive electron more rapidly to

form anion

IONIC BONDINGIONIC BONDING


21/54


The larger the difference in electronegativitybetween two atoms, the stronger the ionic

bond

shows the properties below: The name of the metal also comes first followed

by the non-metal when naming the compound

Easily dissolve in water and in polar solvents; can

conduct electricity tend to form crystalline solids with high melting

temperatures and high boiling temperatures



22/54



` Cation smaller than the parent atom; anion larger

than the parent atom

` Due to donation of electron valance of the metal

atom


23/54




24/54


Ionic compound are solid

Arrangement of repeatingunits of ions in a regularand orderly cubic patternin three dimensions with

the same orientation;crystal lattice

The interaction betweenions cause the structure tobe arrange in alternating

pattern



25/54




26/54


sharing of pairs of electrons between twoor more atoms

involve non-metal elements with same

elements or various elements whichdepends on electronegativity

Similar electronegativities promote greater

bonding; have similar electron density;non-polar

Usually no charged ions are form

COVALENT BONDINGCOVALENT BONDING


27/54


COVALENT BONDINGCOVALENT BONDING


28/54


not strongly attract to each other

have the following properties

tends to exist as liquid or gas or sometimes

solid with a very low MP and BPDo not conduct electricity because they are

neutral

Generally insoluble in water

They are volatile

NONNON--POLAR COVALENTPOLAR COVALENT

BONDINGBONDING


29/54



BONDINGBONDING


30/54



BONDINGBONDING

Double bonds

Triple bonds


31/54


Have difference of electronegativity value;polar covalent bond

The electron density of the more

electronegative element is higherForm a partial negative charge and partial

positive charge

POLAR COVALENT BONDINGPOLAR COVALENT BONDING


32/54


due to the unequal sharing of electronswhere the more electronegative atom will

attract electrons more stronger

To identify the polarity of the compound,it can be determine by calculating the

differences of the electronegativities values

POLAR COVALENT BONDINGPOLAR COVALENT BONDING


33/54


Sometimes the atom with unbondedelectrons (lone pairs) tend to share with

other element or ion which have a room

to occupy the empty space or those withan incomplete outer shell

Also known as coordinate bond with the

symbol

DATIVE COVALENT BONDDATIVE COVALENT BOND


34/54


DATIVE COVALENT BONDDATIVE COVALENT BOND


35/54


Intramolecular attractions: attraction whichhold an individual atom together; ionic

bond, covalent bond

A molecule tends to attract to each otherwith the neighboring molecules; known as

intermolecular attractions

Van der Waals dipole-dipole attractions and

dispersion forces, hydrogen bond

BONDBOND ATTACTIONATTACTION


36/54


Categorized under Van der Waals forceexist between polar covalent molecule

which due to the unequally distribution of

the electrons; polarizedwas said to have a permanent dipole

where each element are partial charge

=0.9

DIPOLEDIPOLE--DIPOLE ATTRACTIONDIPOLE ATTRACTION


37/54


Due to the existence of dipole, a

molecule tends to attract each otherwith the neighboring molecule butrepel each other with same charge

DIPOLEDIPOLE--DIPOLE ATTRACTIONDIPOLE ATTRACTION


38/54


Non-polar molecule have equally distributed electron but it

will be induced when a polar molecule interacts in the

system

DIPOLEDIPOLE--INDUCED ATTRACTIONINDUCED ATTRACTION

Cl Cl


39/54


At some point, the electrons in the non-polar molecule tends tomove towards one end of the molecule to form a temporary partialcharge since the electrons are mobile; instantaneous dipole

DISPERSION FORCESDISPERSION FORCES

Cl Cl


40/54



When interacts with the other same non-polar molecule, the distribution of

electrons will be distort and the molecule

was said to be induced; temporarydipole/instantaneous induced attraction

Also known as a London force


41/54


Happens in mono-atom Element with a large number of electrons will have larger

instantaneous dipole because the protons in nucleus less

hold up the large numbers of electrons in the outer shell,

so it is freely moved and easily to be polarized

Explains the increase in boiling point of noble gas group


Xe Xe Xe Xe


42/54


a special case of dipole forces whichinvolve molecule with large difference of

electronegativity value

attachment of hydrogen atom with thehighly electronegative atom: oxygen,

nitrogen, or fluorine, which has a partial

negative charge whereas hydrogen has the

partial positive charge

H-F: =1.9; HOH: =1.4; H2NH: =0.9

HYDROGEN BONDHYDROGEN BOND


43/54



The hydrogen on one molecule attached toF, O or N that is attracted to an F, O or N

of a different molecule

The strongest intermolecular attractionhowever, water has higher boiling point

then the others because it can form four

hydrogen bond


44/54


In the case of ammonia, the amount ofhydrogen bonding is limited by the fact thateach nitrogen only has one lone pair wherethere aren't enough lone pairs to go aroundto satisfy all the hydrogens

Whereas in hydrogen fluoride, it has only onehydrogen attach to fluorine causing a shortageof hydrogens which will form only twohydrogen bonds

In water, there are exactly the right number ofeach. Water could be considered as the"perfect" hydrogen bonded system.



45/54




46/54


Properties of hydrogen bond

hold the two strands of the DNAdouble helix together

hold polypeptides together in such

secondary structures as the alpha helixand the beta conformation

help enzymes bind to their substrate;antibodies bind to their antigen

help transcription factors bind to eachother

help transcription factors bind toDNA



47/54


Water is the best example of hydrogen bond withseveral unique properties

Has the capability in dissolving many ioniccompounds Oxygen attaches to positive ions by co-ordinate (dative

covalent) bonds whereas hydrogen bonds to negative ionsusing hydrogen bonds

Known as hydration; the compound was said to behydrated

Heavy water: contain a higher proportionthan normal of the isotope deuterium

Hard water: contain high concentrations ofminerals such as Mg2+, Ca2+



48/54




49/54




50/54


Overlapping of atomic orbitals occursbetween atoms/polyatomic molecules

during formation of covalent bond(s)

Each atomic orbitals in an atom need to beoccupy at least one electron which will be

ready to overlap with another one

electron to form a single covalent bond

Two types of covalent bond: sigma bond

() and pi bond ()

HYBRIDIZATION OF ATOMIC

ORBITALS


51/54


Sigma bond (): formation of covalent bondwhen two atomic orbitals on adjacent atomsoverlaps

Overlapping of one end of an atomic orbital

from one atom to another one end of anatomic orbital from another atom

Can be form by the overlapping of two sorbitals, one s orbital with one p orbital and

two p orbitalsThe electron density at the overlapping area

would be the greatest.

SIGMA BONDSIGMA BOND


52/54


s s s-s overlappingExample: H2

s p s-p overlappingExample: HCl

p p p-p overlappingExample: Cl2

SIGMA BONDSIGMA BOND


53/54


The other two p orbitals in one atom willform covalent bond by overlapping sideby side which known as pi bond giving thesymbol of

Pi bond (): formation of covalent bondwhen two p atomic orbitals areoverlapping sideways

Formation of pi bond are weaker thansigma bond as the bond is loosely held bythe atom nuclei

PI BONDPI BOND


54/54

p p sideways one bond

overlappingExample: ethene

PI BOND

Documents

Chap 5 Matter and Chemical Bonding