applied mechanics presentation (finish) (1)

8/10/2019 Applied Mechanics Presentation (Finish) (1)

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Applied Mechanics for Safet

Atomic StructureGROUP MEMBERS:

MUHAMAD SYAHMI AKRAM B. AZIZ PA110

KHALEDA NORLYANA BT ZAINAL PA110

JUWAIRIAH ZAKIRAH BT ABDUL RAZAK PA110

NURUL ATIKAH BT AZMI PA110


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History ofdevelopmen

t of AtomicStructure


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Development of Atomic Model

Democritus460BC

Matter consisted of minute, indivisible and indestparticles known as atoms.

John Dalton1803

All matter is made of atoms

Atom is the simplest and cannot be simpler

JJ Thompson1897

The existence of Electron

This shows Daltons theory was wrong.


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The Quran and Modern Science

God who knows the unseen! Not even the weight of atom(dzharrah)in the heavens or earth escapes Hisknowledge, nor anything smalleror greater. It is allrecorded in a clear Book. (Holy Quran 34:3) (Trans

by Prof Abdel Haleem, Oxford University)

Thus the verse clearly shows that it is possible for something smaller than an atom fact discovered only recently by modern science.


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Rutherford1912

There is Nucleus

Niels Bohr1913

Develop atomic model

Electrons orbiting the shell

James Chadwick1932

Discovered the neutron in 1932.


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ATOMIC STRUCTURE

An atom is the smallest particle that has the properties of the element. Each atom is made up of three th

Protons (P+)- the smallest positively charged unit of matter

Neutrons (N)- the smallest neutral unit of matter (no charge)

Electrons (e-)- the smallest negatively charged unit of matter

Ball shaped center called the nucleus which contains the protons (P+) and the neutrons (N).

Around this nucleus, there are electrons


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CHEMICAL PROPERTIES

Chemical reaction: Tendency of atom to lose and gain electron.Anion (negatively charges)gain electron

Cation ( positively charges)lose electron


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Number of neutrons in regular atoProton number/atomic number of Osmium is 76

oNucleon Number/atomic massof Osmium is 190.23

oRound off the atomic mass to the nearest whole number

190.23 190

oNucleon number of an element is the total number of proton and neutrons in the nucleus of its at

oNeutron number of an element is the total number of nucleon subtract the total number of proto

oTo find number of neutron

N = Mn

N = number of Neutrons

M = atomic Mass

n = atomic number

19076 = 114


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Number of neutrons in an isotopeoProton number/atomic number of Carbon is 6

oNucleon Number/atomic massof Carbon is 12.01 (Figure 1)

oNucleon number of Carbon is 14 ( figure 2)

oIsotope have same number of proton but different number of neutrons.

oIsotope have same number of proton but different number of nucleon.

oNeutron number of an element is the total number of nucleon subtract the total numb

To find number of neutrons

N = Mn

126 = 6

Same number of proton Different

Figure 1 Figure 2


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1) Ionic Bonding

Occurs between + and - ions.

An ionic bond is formed when an atom loses or gains one or more electronouter shell

Requires electron transfer.

Example: NaCl

Ionic materialhard, brittle, electrically and thermally insulative

Binding energylargehigh melting temperature

Na (metal)unstable

electron

+ -CoulombicAttraction

Na (cation)stable

PHYSICAL PROPERTIES


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2) Covalent Bonding

similar electronegativityshare electronsbonds determined by valences& porbitals dominate bonding

Highly directional type of bonding.

Binding energy & melting temperaturevery high (diamond) to very weak (polymeric m

Example: CH4

C: has 4 valence e-,

needs 4 more

H: has 1 valence e-,

needs 1 more

sha

from

sha

from

ato

H

H

H

H

C

CH4


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3) Metallic Bonding

Sea of valence electrons floating on ion coresNon-directional (bonds form in any direction) atoms pack

Binding energy & melting temperature

(wide range)

All elemental metals, highly conductive, ductile.Examples of typical metallic bonding:

cu, al, au, ag, etc.

applied mechanics presentation (finish) (1)

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