JF302 Material Technology: Chapter 1

LOGO

CHAPTER 1 :CHAPTER 1 :MATERIAL STRUCTUREMATERIAL STRUCTURECHAPTER 1 :CHAPTER 1 :MATERIAL STRUCTUREMATERIAL STRUCTURE

© Mechanical Engineering Department

Introduction

• structure of a material give a major impact on its characteristic and behavior

• it can help to control and predict the behavior and performance of materials in various manufacturing processes

•materials can be found in metal and non-metal• the basis for materials formulation•consists from arrangement of atoms that we called crystalline

JF302 – MATERIAL TECHNOLOGY 1CHAPTER 1 : MATERIAL STRUCTURE

ContentContent

JF302 – MATERIAL TECHNOLOGY 1

Material Structure1

The Periodic Table2

Crystal Structure3

Atom Bonding4

CHAPTER 1 : MATERIAL STRUCTURE

Material StructureMaterial Structure

can determine the arrangement of atoms, the density and related properties

can control the material properties a material come from the internal structure of

materialsinternal structure of materials involves how

relationship the atoms with another atoms to form crystals, molecule and micro structures


Material StructureMaterial Structure – cont…

crystal is a homogenous solid formed by a repeating, three-dimensional pattern of atoms, ions, or molecules and having fixed distances between constituent parts.

molecule is the smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms; a group of like or different atoms held together by chemical forces.

micro structure is a structure separated by grain boundaries and requires expansion to be seen


Matter

Pure Substances

Impure Substances (Mixtures)

Elements Compounds Homogeneous Mixtures

Heterogeneous Mixtures

Atoms

Ions

Molecules

Molecules


Material StructureMaterial Structure – cont…

MatterMatter

Matter is a general term for the substance of which all physical objects consist

includes atoms and other substance which have massany object that has mass and occupies volumeall materials whether solid, liquid or gas in the earth is

a mattersubstances of matter may build the : Atom Molecule Ion


ExampleExample


ElementsElements

consisting of small substances which can not be subdivided

a combination of two or more similar atomsin a pure condition


Silver Zinc Cooper

AtomAtom

a basic unit of mattercan not be created and destroyed the substances that make up all material in the form of

solid, liquid or gassmall size, but it has a weight and its own characteristicsconsists of three basic substances such as protons (+),

neutrons (neutral) and electrons (-)An atom is classified according to the number of protons

and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determines the isotope of the element.


AtomAtom – cont…

protons and neutrons contained in the nucleus of an atom, while the electrons are arranged in shells around the nucleus

Nukleus yang mengandungi

proton dan neutron

Elektron

Petala / orbit / kelompang 1

Petala 2

Petala 3


Molecules

is the smallest particle of a substance that retains the chemical and physical properties of the substance

A molecule is formed when two or more atoms join together chemically


CompoundsCompounds

A compound is a molecule that contains at least two different elements

compound exist naturally or artificialit can be separated into simpler substances by

chemical reactions


Benzena (C6H6) Ammonia (NH3) Water (H2O)

What is the difference between a What is the difference between a compound and a molecule?compound and a molecule?

CompoundCompound MoleculeMoleculeA compound is a molecule that contains at least two different elements

A molecule is formed when two or more atoms join together chemically

Water (H2O), carbon dioxide (CO2) and methane (CH4) are compounds because each is made from more than one element

Molecular hydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element


* All compounds are molecules but not all molecules are compounds* All compounds are molecules but not all molecules are compounds

MixturesMixtures

combination of two or more atoms of different types, but are not combined chemically

Mixture refers to the physical combination of two or more substances the identities of which are retained

Mixtures can be either homogeneous or heterogeneous


The difference of a homogenous and The difference of a homogenous and a heterogeneous mixturea heterogeneous mixture

Homogenous Heterogeneousa mixture of more than one substance that appears to be all one substance; also called a solution

a mixture of more than one substance in which there are visible, different parts

have uniform composition and properties throughout

aren't uniform in composition and properties throughout

unseparable by mechanical methods

separable by mechanical methods

Example : air, alloy, paint, margarine, blood etc

Example : concrete, sand, pizza, soil, muddy water etc


The Periodic TableThe Periodic Table

In 1869, Dmitri Mendeleev developed the first periodic table based on atomic mass:

(atomic mass= #protons+#neutrons in the nucleus of the atom)

In 1913, Thomas Moseley developed the modern periodic table based on atomic number

(atomic number= #protons in the nucleus of the atom)The modern periodic table is arranged in columns and

rowsColumns go up and downRows go from left to right


The Periodic Table The Periodic Table – cont…

Groups or FamiliesColumns are called: Groups or FamiliesThere are 18 groups or families in the periodic tableElements in the same group or family have the same

number of valence electronsValence electrons are the number of electrons in the

outer most energy level


Elements within a group have similar physical and chemical properties

All have the same number of electrons in their outermost or valence shells

Example Na (2,8,1) and K (2,8,8,1) are both in Group 1


The Periodic TableThe Periodic Table – cont…

Let’s look at a few elements…

HydrogenHeliumLithiumFluorineArgon



Group Number Group Name Valence Number

1 Alkali Metals 1

2 Alkaline Earth Metals 2

3 -12 Transitional Elements 1 or 2

13 Boron family 3

14 Carbon family 4

15 Nitrogen family 5

16 Oxygen family 6

17 Halogens 7

18 Noble Gases 8



Groups or FamiliesGroup 1 has 1 valence electron 2 2 13 3 14 4 15 5 16 6 17 7 18 8*Groups 3-12 do not follow this pattern



Periods Periods are the portion of the periodic table that go

from up to down. There are 7 periods in the periodic table.All elements in the same period, have the same

number of energy levels.Energy levels are where the electrons are located




ELECTRON CONFIGURATIONELECTRON CONFIGURATION

is the arrangement of electrons of an atom, a molecule, or other physical structure

knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements

each shell can only be filled by the number of electrons only

if a shell has been fully filled, the electrons have to be filled in the next shell

electrons will occupy the orbit closest to the nucleus before occupying another shell


THE PERIODIC TABLE FEATURESTHE PERIODIC TABLE FEATURES

chemical properties of an atom depends on the number of electrons in the outer shells of atoms, called atomic valence

elements have the same number of electrons in the outer shell will be included in the same group

each period have the same number of shellswhen the electron is increased, the properties of the

metal elements become less and less


USE OF THE PERIODIC TABLEUSE OF THE PERIODIC TABLE

know, understand and forecast chemistry and physics properties of an element

easy to remember the characteristics of a particular element in the position of the periodic table

recognize and identify the specific elements of different groups

make a study more about the elements of the existing and new found


Crystal StructureCrystal Structure

Amorphous

is a particles are randomly arranged and formed as a result of rapid cooling

Crystalline

is a particles are arranged in order and formed as a result of the slow cooling

Crystal Structure


consists from arrangment of atoms in a three-dimensional in solidification of atomic process, molten metal will react

with each other and organize their respective positions in a uniform and orderly

this arrangement is called space lattice processThe types of crystal structures

1. Simple Cubic (SC)

2. Body-Centered Cubic (BCC)

3. Face-Centered Cubic (FCC)

4. Hexagonal-Close Packed (HCP)


Crystal StructureCrystal Structure – cont…

SIMPLE CUBIC (SC)SIMPLE CUBIC (SC)


the simple cubic unit cell is a cube (all sides of the same length and all face perpendicular to each other) with an atom at each corner of the unit cell

there are eight atoms at the corners and each such atom makes

a simple cubic unit cell has :

8 (at corners) x 1/8 = 1 atoms

EXAMPLE OF SIMPLE CUBIC (SC)EXAMPLE OF SIMPLE CUBIC (SC)


Sodium Chloride


this type of unit cell has eight atoms at corners and one at the body center.

each corner atom makes 1/8 contribution and the atom at the body center belongs only to the particular unit cell.

a body-centered cubic unit cell has :

8 (at corners) x 1/8 + 1 (at body center) x 1 = 2 atoms

BODY-CENTERED CUBIC (BCC)BODY-CENTERED CUBIC (BCC)

EXAMPLE OF BCCEXAMPLE OF BCC


Chromium Iron

Sodium Tungsten


a face centered cubic unit cell has one atom at each corner and one atom at each face center

being shared by two unit cells and making a contribution of only ½ to a particular unit cell

a face-centered cubic unit cell has :

8 (at corners) x 1/8 + 6 (at face centers) x ½ = 4 atoms

FACE-CENTERED CUBIC (FCC)FACE-CENTERED CUBIC (FCC)

EXAMPLE OF FCCEXAMPLE OF FCC


Silver Gold

Copper Aluminum


the unit cell for the hexagonal closest-packed structure has a diamond-shaped or hexagonal base with sides of equal length

the base is perpendicular to the longest side of the unit cell an atom is centered on each corner of the unit cell a hexagonal closest-packed unit cell has : 12 (at corners) x 1/6 + 2 (at face centers) x ½ + 6 (at sides) x ½ = 6 atoms

HEXAGONAL-CLOSE PACKED (HCP)HEXAGONAL-CLOSE PACKED (HCP)

EXAMPLE OF HCPEXAMPLE OF HCP


Zinc Titanium

Cobalt

Ionic

Covalent

Metallic

BONDINGBONDING


ATOMIC BONDINGATOMIC BONDING


also called electrovalent bonda type of chemical bond formed through an

electrostatic attraction between two oppositely charged ions

formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal

a bond forms when one or more electrons are transferred from one neutral atom (metal) to another atom (non-metal)

the two types of ion are held together by electrostatic forces

IONIC BONDSIONIC BONDS


EXAMPLE : Natrium Chloride (NaCl)EXAMPLE : Natrium Chloride (NaCl)


EXAMPLE : Magnesium Chloride (MgClEXAMPLE : Magnesium Chloride (MgCl22))


form when atoms share one or more pairs of electrons usually happens between nonmetalscan classified into single, double, and triple covalent

bond with respect to mutual sharing of one, two, and three bonds respectively

COVALENT BONDSCOVALENT BONDS


EXAMPLE : Water (HEXAMPLE : Water (H22O)O)


EXAMPLE : Oxygen Molecule (OEXAMPLE : Oxygen Molecule (O22))


formed between two or more metal cations metal atoms release their valence electrons into a sea

of valence electrons shared by all of the metal atoms

the attraction of these free electrons to the metal cations is called a metallic bond

METALLIC BONDSMETALLIC BONDS


Each atom releases its two valence electrons into a pool of electrons to be shared by all of the metal atoms.

EXAMPLE : A GROUP 2 METALEXAMPLE : A GROUP 2 METAL


Metals are ductile – they can be drawn into wires.

Metallic Bonding explains some Metallic Bonding explains some physical properties of Metalsphysical properties of Metals


Metals are good electrical conductors because the valence electrons are free to travel

Metallic Bonding explains some Metallic Bonding explains some physical properties of Metalsphysical properties of Metals


Atomic View of Metallic BondingAtomic View of Metallic Bonding

• Bonding in metals is not rigid.

• The same ability to reorganize explains why metals can be pulled into long, thin wires.

• As a metal is struck by a hammer, the atoms slide through the electron sea tonew positions while continuing to maintain their connections to each other.


Metal atoms are arranged in very Metal atoms are arranged in very compact and orderly patternscompact and orderly patterns


Compare and Contrast Types of BondingCompare and Contrast Types of Bonding

Metallic and ionic bonding involve electrostatic attractions between positive and negatively charged particles.

Metallic bonding shares electrons among the ions in a similar manner to how electrons are shared in covalent bonding.

Covalent bonding shares electrons rather than having electrostatic charges.

Ionic bonding will form compounds whereas covalent bonding can form a compound or element and metallic bonding is strictly found in elements

Similarities Differences

JF302 Material Technology: Chapter 1

Education

material properties

different atoms

arrangement of atoms

different elements atoms

similar atoms

atoms of different types

matter substances of

introduction structure