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1/5 Making Steel Alloy
* * * SIT WITH YOUR DURABILITY GROUPS and/or 3 or 4’s
1. Take out your Video HW notes #26 Alloys
2. You should have already submitted the Durability Lab,
Paint Lab, Paint CER, &Electroplating CER before break
Essential Questions for this Unit
How are chemistry and art connected?
Describe how the chemical
behavior of metals is related
to their atomic structure.
Which materials are resistant
to acid rain damage and
therefore durable for artwork?
Why and how do you
electroplate one metal with
another?
How can two soluble
solutions react in a double
replacement reaction?
How can you use precipitates
to make pigment for creating
different color paint?
Describe how the physical
behavior of metals is related
to their atomic structure.
How can you make alloys that
have improved properties
compared to pure metals.
How do you design a reliable
scientific experiment?
Review of Ionic Bonding
Ionic Bonding
Metals _______
lose e- to become ________
positively
charged ions called _______________
.
cations
Non-metals gain
____ e- to become __________
negatively
charged ions called _______________
.
anions
The _________________
charged ions
oppositely
__________
and form _________
ionic bonds.
attract
Crystalline Structure
Na+ Cl- Na+ ClCl- Na+ Cl-
Na+
Non-metal
Anions
Metal
Cations
Na+ Cl- Na+ ClCl- Na+ Cl-
Na+
Crystal LATTICE of
oppositely charged
ions, e- have already
been transferred
from M to NM
Ionic Solids NOT Good Conductors
1) Why can’t solid ionic compounds conduct
electricity until they are dissolved into ions?
• Dissolved ions have a charge and thus act like a
flow of e- which is electricity!
• Ionic solids exist as a lattice
of oppositely charged ions
where the e- are LOCALIZED
Na+ Cl- Na+ Cl-
localized means set in
specific area, can not move
far from their original atom
Na+ Cl- Na+ Cl-
Cl- Na+ Cl- Na+
Cl- Na+ Cl- Na+
Hard, yet so brittle
2) Why are ionic solids so brittle?
Na+ •ClWhen
Cl- the
Na+struck
IONS in the crystal
+ Cl+
Cl- Nalattice
Na
SHIFT.
Na+ •ClSimilarly
Na+ Clcharged
ions REPEL and the
+ ClCl- Nacompound
Na+breaks.
Metallic Bonding
Metallic
Bonding
When a substance is made up of only
share
metal atoms, the metal cations ______
valence electrons.
all of the ___________
______
The metal cations are surrounded by a
“ ____________
sea of electrons
delocalized ______
Atomic Structure of Metals
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Valence
electron
Metal
Cations
Sea of metal cations
SHARING all of each
other’s DELOCALIZED
valence e-
Ionic Solids NOT Good Conductors
1) Why are most metals very lustrous and
good conductors of heat and electricity?
• Valence e- in a metal are shared by all the metal
atoms and can move freely, thus good conductors
• e- absorb light and are
excited easily. They relax
and emit nearly all the light
they absorb, thus most
metals are shiny
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Metals Are NOT Brittle
2) Why are most metals malleable?
• When a metal is struck the atoms SHIFT
pass each other WITHOUT REPULSION.
• Delocalized e- REARRANGE instantaneously
around the cations to keep charge balance
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Cu2+
Examples of Alloys
An _________ is a ________________________
homogeneous solution of different solids
(usually metals). These pure metals are combined in order to improve the
_______________________________________________________________
Luster,
malleability, hardness, durability, resist rusting or corrosion, etc.
alloy
BRASS
ALLOY
BRONZE
ALLOY
Copper & Zinc
Copper & Tin
GOLD
ALLOY
Gold & Silver & Copper
STEEL
ALLOY
Iron & Carbon
Visualizing the e- Sea Model of Metallic Bonding
Manipulating the Properties of an Alloy
Spring Steel
Fe2+ C
Fe2+
Annealed Steel
Fe2+ C Fe2+
Fe2+
Fe2+ C
2+
Fe
C
Heat red-hot
Cool Slowly
Fe2+
Fe2+
Fe2+
“snaps back”
C
Fe2+
Fe2+ C Fe2+
Fe2+
Malleable b/c atoms can
shift when heated and the
crystal reorganizes while
cooling slowly
Manipulating the Properties of an Alloy
Annealed Steel
Fe2+
C
Heat red-hot
Cool Quickly
Fe2+
C
Hardened Steel
Fe2+ C Fe2+
C
Fe2+
Fe2+
C
Fe2+
Fe2+ C Fe2+ C Fe2+
C
C
Fe2+
Fe2+
C
C
C
Fe2+
C
Fe2+
Brittle b/c extra C creates
stress points in the crystal,
these “dislocations” prevent
planes of atoms from slipping
Slips and Dislocations
Manipulating the Properties of an Alloy
Hardened
C
Heat
red-hot Heat
Steel Cool Gently
Quickly
Fe2+ C Fe2+
C
C
Fe2+
Fe2+
C
C
C
Fe2+ C Fe2+ C Fe2+
C
Tempered Steel
C
Fe2+
C
Fe2+
Fe2+
Fe2+
Fe2+
C
C
Fe2+
Fe2+
Strong (hard, but not brittle)
yet malleable b/c some stress
is relieved when gently heated
Manipulating the Properties of an Alloy
1) Ratio of different elements
2) How it is heated
3) How it is cooled
Manipulating the Properties of an Alloy
________Steel
______Steel
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Manipulating the Properties of an Alloy
________Steel
______Steel
Fe2+
Fe2+
C
Fe2+
C
Fe2+
Fe2+
Fe2+
C
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Fe2+
Manipulating the Properties of an Alloy
_______Steel
______Steel
C
Fe2+
Fe2+ C Fe2+
C
C
Fe2+ C Fe2+ C Fe2+
C
C
Fe2+
C
Fe2+
Fe2+
Fe2+
C
Fe2+
Fe2+
Fe2+
Fe2+
Manipulating the Properties of an Alloy
“Grains” within metal crystals