WHAT IS MATTER?

Atom Elements Compound Mineral Rocks

Smallest Largest

Is the smallest particle of an element and has the same chemical properties of the element

Atoms:

– the stuff that builds elements

– the smallest particle that uniquely defines an elemen

Particles that make up an atom:

Protons: positive (+) charge

Neutrons: no charge

Electrons: negative (-) charge

Protons + neutrons define the nucleus of an atom.

Layers of electrons that orbit around the nucleus are called orbitals or energy -level shells.

ATOM

ATOM STRUCTURE

ATOM STRUCTURE

A substance composed of a single kind of atom

Elements contain one or more of the same type of atom!

Cannot be broken down into another substance by chemical or

physical means.

ELEMENTS

A substance in which two or more dif ferent elements are

CHEMICALLY bonded together

COMPOUND

Two or more substances that are mixed together but are NOT

chemically bonded.

MIXTURE

PERIODIC TABLE ELEMENTS

The arrangement of the chemical elements with increasing

atomic number according to the periodic variation in electron

structure. Nonmetallic elements are positioned at the far

right-hand side of the table.

DEFINE PERIODIC TABLE

WHAT HAVE INSIDE THE BOX OF EPT?

Atomic Number

Symbol of Element

Atomic Weight

Name of Element

WHAT IS ATOMIC NUMBER?

Atomic Number

Atomic numbers represent the number of

protons in one atom of the element.

WHAT IS ATOMIC MASS?

Atomic Number

A sum of the number of

protons and neutrons in

the nucleus

WHAT IS SYMBOL?

Symbol of Elements

Explains name of the element.

Arrangements of electrons in an atom.

Each orbital can have only 2 electrons and with dif ferent

quantum numbers.

ELECTRON CONFIGURATION

1) Oxygen

Atomic Number=8

Shell Number=2

Group=? – lets determine it through atomic orbit.

Solution

1) Filled up electron at first shells

2) The balance of electron number left will be fill up at outer shell. Then it

shows the group of Oxygen.

EXAMPLE ELECTRON CONFIGURATION

Oxygen-atomic orbit

crystal structure is a unique arrangement of atoms or molecules in a crystall ine l iquid or solid.

A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long -range order and symmetry. Patterns are located upon the points of a lattice, which is an array of points repeating periodically in three dimensions. The points can be thought of as forming identical tiny boxes, called unit cells, that fi l l the space of the lattice. The lengths of the edges of a unit cell and the angles between them are called the lattice parameters. The symmetry properties of the crystal are embodied in its space group.

A crystal's structure and symmetry play a role in determining many of its physical properties, such as cleavage, electronic band structure, and optical transparency.

CRYSTAL STRUCTURE

CRYSTALLIZED STRUCTURE

Simple cubic

Body-centered cubic

No of atoms:

8 corner atom x 1/8 = 1 atom

Total atom = 1 atom

No of atoms:

8 corner atom x 1/8 = 1 atom

1 centre atom = 1 atom

Total atom = 2 atoms

CRYSTALLIZED STRUCTURE

(CONT.)

Face-centered cubic

Hexagonal close-packed

No of atoms:

12 corner atom x 1/6 = 2

atoms

2 centre atom x ½ = 1

atom

3 centre atom = 3

atoms

Total atom = 6

atoms

No of atoms:

8 corner atom x 1/8 = 1 atom

6 face corner x ½ = 3 atoms

Total atom = 4 atoms

TO BE CONTINUED UNTIL

ALL STUDENT SUBMIT

THE ASSIGNMENT!!!

Adapted from Fig. 2.10, Callister 6e.

COVALENT BONDING

Electrons are shared (as opposed to transferred) between

atoms in their outermost shells to achieve a stable set of

eight

Atoms of one element give up their outer electron(s), which

are in turn attracted to atoms of some other element to

increase electron count in the outermost shell to eight.

IONIC BOND

Sharing of outer shell electrons by all atoms to form a general

electron cloud that permeates the entire block.

METALLIC BONDING

Some metals are important as pure elements (e.g ., gold,

silver, copper)

Most engineering applications require the enhanced

properties obtained by alloying

Through alloying, it is possible to increase strength, hardness,

and other properties compared to pure metals.

METALS AND ALLOYS

Solid solution is an alloy in which the solute atoms are

distributed in the solvent matrix and has same structure of

the solvent.

The elements which present in larger amount in the alloy is

called solvent and the other elements is called solute.

There are two type of solid solution

1) Substitutional

2) Interstitial

SOLID SOLUTIONS

The atoms of the solvent metal are replaced in the crystal

lattice by the atoms of the solute.

Subtitutional solid solution formation is favoured when the

atomic sizes of the two metals are almost equal.

SUBTITUTIONAL SOLID SOLUTION

Subtitutional solid solution

Are formed only when the atoms of the solute elements are

very small compared with those of the solvent, thus enabling

them to fit into interstices or spaces in the crystal lattice of

the solvent.

INTERSTITIAL SOLID SOLUTION

Interstitial solid solution

METAL SOLIDIFICATION

METAL AND ALLOY COOLING CURVE

Pure metals solidify at a constant

temperature.

Alloys solidify within a temperature range

PHASE DIAGRAM

A solidus is a line below which the substance is stable in the

solid state.

A liquidus is a line above which the substance is stable in a

liquid state

Composition is expressed in weight percent(wt%) of each

elements in the phase.

Phase - can exist over a range of temperatures and

compositions, but it 's atomic structure will remain the same.

There to be three phases, or states of matter: gas, liquid and

solid.

An equilibrium diagram (or phase diagram) is a diagram with

T and X (or W) as axes, showing the equilibrium constitution.

TERMS OF EQUILIBRIUM PHASE DIAGRAM