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Universities » University of New Hampshire (UNH.. » MS - Materials Science » 401 - Science of Stuff » Flash Cards

J-term Quiz 2 - Flashcards

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Class:MS 401 - Science of Stuff
Subject:Materials Science
University:University of New Hampshire-Main Campus
Term:Fall 2011
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4 Classes of traditional Materials -Metals
- Ceramics
- Polymers 
4 Classes of advanced Materials -Semiconductors
- Biomaterials
- Smart Materials
- Nano materials
Definition of 'Advanced Materials' -High technology applications
-Traditional materials with enhanced properties 
-Newly developed materials
- Usually expensive 
Biomaterials -Components implanted in the human body 
- Cannot produce toxins 
- Must be compatible with Bodily tissues
A biomaterial is any matter, surface, or construct that interacts with biological systems.
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Smart Materials -These materials can sense a change in environment and respond in a predetermined manner
- Components of smart materials include some type of sensor (detects change) and an actuator (responds to change) 
Semiconductors - Made primarily from metalloids 
-Extremely controlled chemical purity 
- Adjustable conductivity of electricity 
- opaque to visible light 
- shiny
- some have good plasticity but others are fairly brittle 
- some have high electrical responses to light 
EX) Si, Ge, GaAs, InSb
Nanomaterials -We now have the ability to manipulate atoms and groups of atoms
-the size of the "building blocks" is less that 100 nanometers
Density -The measure of how heavy an object is for a given size or amount og space it takes up

-Mass of a material per unit volume
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Stiffness -Measure of a materials ability to resist elastic deformation by a force 
- Elastic deformation is not permanent: When the force is removed, the piece returns to it's original shape 
-A "stiff" material requires a lot of force to elastically deform it
Strength -Elastic deformation lasts only so long before permanent deformation occurs
-Permanent deformation is called plastic deformation 
-The strength of a material is a measure of its resistance to plastic deformation 
Toughness -Toughness is the ability of a material to absorb energy before fracture 
-A tough material requires a lot of energy to break 
Resistivity -The measure of the ability of a material to resist the flow of electrons 

-Resistivity is important in any product which conducts electricity
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Atom The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
-Cannot be further broken down 
-An element is a substance made up of one kind of atom
History of Atomic theory 3 people's proposals -Democritus- proposed the idea of atoms to settle an ancient debate

-Heraclitus proposed that everything changes

-Parmenides- argued that change is logically impossible because matter would have to pass into nothingness
Democritus' Theory - Matter is composed of indestructible units called atoms 
- Atoms remain unchanged but combine in various ways to form all macroscopic objects 
-Characteristics of an object are determined by the shape of its atoms 
IE) sweet things have smooth atoms and bitter things have sharp atoms 
Dalton's atomic theory Dalton proposed the modern atomic theory in 1808
-Dalton's atoms were tiny spheres with hooks that could connect to other atoms 
--Every element is made of atoms 
--All atoms of any element are the same 
--Atoms of different elements are different 
-- Atoms are not made changed or destroyed in chemical reactions 
-- Atoms combine to form molecules 
-- Molecules contain atoms of different elements in fixed proportions
-- Compounds are substances containing the same molecule 
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The electron - The atom contains electrons, neutrons and protons
- The electron is very small: it weighs 9.1x10(-28) grams 
- The electron has a negative charge
-Discovered by J.J. Thompson in 1897
J.J. Thompson's ideas Thompson discovers electron in 1897

- He proposes the "plum pudding" model of an atom 

- The atom is composed of electrons surrounded by a soup of positive charge 
Ernest Rutherford - Rutherford discovered the nucleus between 1909- 1911. He bombarded a  piece of gold with alpha particle radiation (nuclei from helium atom) 
- most of the particles past through the foil but some (0.1%) bounced back
--Rutherfords model of an atom 
- The atom is a positively charged nucleus with negatively charged electrons circling it 
The proton Positively charged

Proton weighs almost 2000 times as much as the electron 

1835 times heavier than the electron 

weighs 1.6x10(-24) grams
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The Neutron -Discovered in 1932 by James Chadwick 
-Electrically neutral 
-Weighs about the same as the proton
-Nucleus contains protons and neutrons 
Bohrs model of an atom in 1913 Bohr proposes that the electrons orbiting an atom could only exist at certain distances from the nucleus 
-these electron orbits where called shells 
-the distance from the nucleus determines the energy of the electrons
-therefore the electrons could only have certain energies 
Scanning tunneling microscope -1981 a microscope was invented by the scientists at IBM that could "See" atoms
-very small needle tip that conducts electricity 
- When the tip encounters an atom, it senses a tunneling current 
- the microscope measures the current at many points and a computer records the current at each point 
Four forces of nature -the strong force
- the weak force 
- electromagnetic force
- gravitational force 
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The strong force -Responsible for holding the nuclei of atoms together
-Very Strong, but short ranged 
- Acts over ranges of 10(-13) cm 
- Basically attractive but can be equally as repulsive in some circumstances 
The weak force Responsible for radioactive decay 
-Very short range and very weak 
Gravitational force Weak but very long ranged
-Always attractive 
- Acts between any two pieces of matter in the universe since mass is its source
Electromagnetic force -causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets 
-Long ranged but much weaker than the strong force
-Attractive or repulsive
-Acts only between pieces of matter carrying an electrical charge 
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Neutral Charge - an atom or an object is neutral is it has an equal number of electrons and protons because the charges cancel each other out 
Positive and negative charges - An atom becomes positive if it loses electrons  and has more protons than electrons 

- An atom becomes negatively charged if it gains electrons and has more electrons than protons
What is a coulomb? - The amount of charge can be measure 
-Charge is measured in units called coulombs abbreviated "C"
- One Coulomb is a huge charge . an object would need 6.25 x 10(-19) extra electrons to have a charge of -1 coulombs 
- an electron has a charge of -1.6 x10(-19) C
- the estimated amount of charge carrie by a lightening bolt is about 10 coulombs 
Coulombs law -Opposite charges attract
-Like charges repel 
-the force between charges increases as the charge increases
-The force between charges decreases if the distance between them increases 
- Charges attract or repel one another even if they are not touching : this electrostatic force is called non-contact force
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Charging by friction -Charging an object by rubbing it against another object 
-Rubbing objects together can cause electrons to move from one object to another 
- only electrons move
- electrons are transferred, not created and not destroyed, this is called conservation of charge 
Electron affinity Some materials attract electrons more than others 

materials with higher electron affinity can attract electrons from materials with a lower electron affinity 
triboelectric series a table that ranks materials from lowest electron affinity (become positive) to highest electron affinity (become negative) 

-Tribology - the science of the mechanisms of friction, lubrication, and wear of interacting surfaces in relative motion (greek "tribos" a rubbing) 
Polarization - The process in which a charged object causes the electrons in another object to move, becoming polarized 
-the negatively and positively charged electrons in an object separate and move to opposites ends of the object giving it a positive and a negative end 
- a negative charge will push electrons away in the object
- a positive charge will attract electrons in the object 
- once polarized, a negative charged can be attracted to the positive part of the polarized object and same with the positive to negative 
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periodic table -A table in which the elements are arranged by atomic number in columns (groups) and rows (periods) 

- It is called the periodic table because of the periodic law which states that when elements are arranged by atomic number they exhibit a periodic trend (or recurrence) in properties 
atomic number  the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus.
Electronegativity Electronegativity, symbol , is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.

- The stronger the electronegativity the greater an elements ability to attract electrons to it's self 

-Most highly electronegative - Nitrogen, Oxygen, Flourine, chlorine 
Primary bonds -Occur between atoms: electrostatic attraction beween nuclei and electrons 
-stronger bonds 

- Ionic 
- Metallic
- covalent 
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Secondary bonds - occurs between molecules over a greater distance than primary bonds

-Hydrogen bonds (dipole, dipole bonding)
- Van Der Waals force
ionic bond
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 4 Classes of traditional Materials-Metals
- Ceramics
- Polymers 


 4 Classes of advanced Materials-Semiconductors
- Biomaterials
- Smart Materials
- Nano materials

 Definition of 'Advanced Materials'-High technology applications
-Traditional materials with enhanced properties 
-Newly developed materials
- Usually expensive 
 Biomaterials-Components implanted in the human body 
- Cannot produce toxins 
- Must be compatible with Bodily tissues
A biomaterial is any matter, surface, or construct that interacts with biological systems.
 Smart Materials-These materials can sense a change in environment and respond in a predetermined manner
- Components of smart materials include some type of sensor (detects change) and an actuator (responds to change) 
 Semiconductors- Made primarily from metalloids 
-Extremely controlled chemical purity 
- Adjustable conductivity of electricity 
- opaque to visible light 
- shiny
- some have good plasticity but others are fairly brittle 
- some have high electrical responses to light 
EX) Si, Ge, GaAs, InSb
 Nanomaterials-We now have the ability to manipulate atoms and groups of atoms
-the size of the "building blocks" is less that 100 nanometers
 Density-The measure of how heavy an object is for a given size or amount og space it takes up

-Mass of a material per unit volume

 Stiffness-Measure of a materials ability to resist elastic deformation by a force 
- Elastic deformation is not permanent: When the force is removed, the piece returns to it's original shape 
-A "stiff" material requires a lot of force to elastically deform it
 Strength-Elastic deformation lasts only so long before permanent deformation occurs
-Permanent deformation is called plastic deformation 
-The strength of a material is a measure of its resistance to plastic deformation 
 Toughness-Toughness is the ability of a material to absorb energy before fracture 
-A tough material requires a lot of energy to break 
 Resistivity-The measure of the ability of a material to resist the flow of electrons 

-Resistivity is important in any product which conducts electricity
 AtomThe atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
-Cannot be further broken down 
-An element is a substance made up of one kind of atom
 History of Atomic theory 3 people's proposals-Democritus- proposed the idea of atoms to settle an ancient debate

-Heraclitus proposed that everything changes

-Parmenides- argued that change is logically impossible because matter would have to pass into nothingness
 Democritus' Theory- Matter is composed of indestructible units called atoms 
- Atoms remain unchanged but combine in various ways to form all macroscopic objects 
-Characteristics of an object are determined by the shape of its atoms 
IE) sweet things have smooth atoms and bitter things have sharp atoms 
 Dalton's atomic theoryDalton proposed the modern atomic theory in 1808
-Dalton's atoms were tiny spheres with hooks that could connect to other atoms 
--Every element is made of atoms 
--All atoms of any element are the same 
--Atoms of different elements are different 
-- Atoms are not made changed or destroyed in chemical reactions 
-- Atoms combine to form molecules 
-- Molecules contain atoms of different elements in fixed proportions
-- Compounds are substances containing the same molecule 
 The electron- The atom contains electrons, neutrons and protons
- The electron is very small: it weighs 9.1x10(-28) grams 
- The electron has a negative charge
-Discovered by J.J. Thompson in 1897
 J.J. Thompson's ideasThompson discovers electron in 1897

- He proposes the "plum pudding" model of an atom 

- The atom is composed of electrons surrounded by a soup of positive charge 
 Ernest Rutherford- Rutherford discovered the nucleus between 1909- 1911. He bombarded a  piece of gold with alpha particle radiation (nuclei from helium atom) 
- most of the particles past through the foil but some (0.1%) bounced back
--Rutherfords model of an atom 
- The atom is a positively charged nucleus with negatively charged electrons circling it 
 The protonPositively charged

Proton weighs almost 2000 times as much as the electron 

1835 times heavier than the electron 

weighs 1.6x10(-24) grams
 The Neutron-Discovered in 1932 by James Chadwick 
-Electrically neutral 
-Weighs about the same as the proton
-Nucleus contains protons and neutrons 


 Bohrs model of an atomin 1913 Bohr proposes that the electrons orbiting an atom could only exist at certain distances from the nucleus 
-these electron orbits where called shells 
-the distance from the nucleus determines the energy of the electrons
-therefore the electrons could only have certain energies 
 Scanning tunneling microscope-1981 a microscope was invented by the scientists at IBM that could "See" atoms
-very small needle tip that conducts electricity 
- When the tip encounters an atom, it senses a tunneling current 
- the microscope measures the current at many points and a computer records the current at each point 
 Four forces of nature-the strong force
- the weak force 
- electromagnetic force
- gravitational force 

 The strong force-Responsible for holding the nuclei of atoms together
-Very Strong, but short ranged 
- Acts over ranges of 10(-13) cm 
- Basically attractive but can be equally as repulsive in some circumstances 
 The weak forceResponsible for radioactive decay 
-Very short range and very weak 

 Gravitational forceWeak but very long ranged
-Always attractive 
- Acts between any two pieces of matter in the universe since mass is its source

 Electromagnetic force-causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets 
-Long ranged but much weaker than the strong force
-Attractive or repulsive
-Acts only between pieces of matter carrying an electrical charge 
 Neutral Charge- an atom or an object is neutral is it has an equal number of electrons and protons because the charges cancel each other out 
 Positive and negative charges- An atom becomes positive if it loses electrons  and has more protons than electrons 

- An atom becomes negatively charged if it gains electrons and has more electrons than protons
 What is a coulomb?- The amount of charge can be measure 
-Charge is measured in units called coulombs abbreviated "C"
- One Coulomb is a huge charge . an object would need 6.25 x 10(-19) extra electrons to have a charge of -1 coulombs 
- an electron has a charge of -1.6 x10(-19) C
- the estimated amount of charge carrie by a lightening bolt is about 10 coulombs 
 Coulombs law-Opposite charges attract
-Like charges repel 
-the force between charges increases as the charge increases
-The force between charges decreases if the distance between them increases 
- Charges attract or repel one another even if they are not touching : this electrostatic force is called non-contact force
 Charging by friction-Charging an object by rubbing it against another object 
-Rubbing objects together can cause electrons to move from one object to another 
- only electrons move
- electrons are transferred, not created and not destroyed, this is called conservation of charge 
 Electron affinitySome materials attract electrons more than others 

materials with higher electron affinity can attract electrons from materials with a lower electron affinity 
 triboelectric seriesa table that ranks materials from lowest electron affinity (become positive) to highest electron affinity (become negative) 

-Tribology - the science of the mechanisms of friction, lubrication, and wear of interacting surfaces in relative motion (greek "tribos" a rubbing) 


 Polarization- The process in which a charged object causes the electrons in another object to move, becoming polarized 
-the negatively and positively charged electrons in an object separate and move to opposites ends of the object giving it a positive and a negative end 
- a negative charge will push electrons away in the object
- a positive charge will attract electrons in the object 
- once polarized, a negative charged can be attracted to the positive part of the polarized object and same with the positive to negative 
 periodic table-A table in which the elements are arranged by atomic number in columns (groups) and rows (periods) 

- It is called the periodic table because of the periodic law which states that when elements are arranged by atomic number they exhibit a periodic trend (or recurrence) in properties 
 atomic number the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus.
 ElectronegativityElectronegativity, symbol , is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.

- The stronger the electronegativity the greater an elements ability to attract electrons to it's self 

-Most highly electronegative - Nitrogen, Oxygen, Flourine, chlorine 
 Primary bonds-Occur between atoms: electrostatic attraction beween nuclei and electrons 
-stronger bonds 

- Ionic 
- Metallic
- covalent 
 Secondary bonds- occurs between molecules over a greater distance than primary bonds

-Hydrogen bonds (dipole, dipole bonding)
- Van Der Waals force
 ionic bond
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