MATL 240 FINAL EXAM QUESTIONS AND VERIFIED
ANSWERS
Four Main Types of Engineering Materials - Answers - Metals, polymers, ceramics,
composites
2 Main Areas of Material Science - Answers - extractive material science and physical
material science
Extractive Material Science - Answers - Deals with removing raw material from the earth
and processing it into an engineering material
Physical Material Science - Answers - Deals with how the properities of materials are
altered by processing
3 Main Types of Material Properties - Answers - Physical, mechanical, chemical
Physical Properites - Answers - these are inherent to the material-Density, thermal
expansion, thermal conductivity, electrical conductivity
Mechanical Properties - Answers - how the material reacts or responds to an external
force-hardness, strength, ductility, toughness, impact strength, fatigue strength
Chemical Properties - Answers - how the material reacts with its environment-corrosion
resistance
Element - Answers - pure sucstance that can not be broken down into a simpler
substance-approximately two thirds of all elements are metallic
Atoms - Answers - smallest part of an element that retains the properties of the element
Atoms are made up of - Answers - protons, neutrons, electrons
Protons - Answers - in the nucleus, positive charge, approximately 1 AMU
Electrons - Answers - orbits the nucleus, negative charge, approximately 1/1837 AMU
Neutrons - Answers - in the nucleus, no charge, approximately 1 AMU
Atomic Bonding - Answers - occurs because the atoms are trying to get to their lowest
energy state-this is when they have full outer electron shells (valence shells)
Main Types of Atomic Bonding - Answers - Covalent, Ionic, Vander Walls, Metallic
, Covalent - Answers - one atom shares its valence electrons with another atom so each
have full valence electron shells
Ionic - Answers - one atom gives its valence electrons to another atom so each have full
valence electron shells-materials with ionic and covalent bonds are typically poor
electrical conductors because the electrons are held in fixed positions
Vander Walls - Answers - weak electrostatic bonds-important for thermoplastics
Metallic - Answers - "sea of electrons"-electrons move from atom to atom so each feels
it has a full valence shell-this makes metals good electrical conductors
States of Matter - Answers - Gas, liquid, solid
Gas - Answers - atoms do not have short range or long range order, shape and volume
are not fixed
Liquid - Answers - atoms have some short range order, volume is fixed, shape assumes
that of the container
Solid - Answers - atoms have long range order, shape and volume are both fixed
Solidification of Metals: 3 Stage Process - Answers - Step 1: Nucleation-two atoms that
are close together form a chemical bond
Step 2: Growth-additional atoms bond to the nuclei formed in stage one
Step 3: Formation of the Grain Boundaries-this occurs when grains of different
orientation intersect
Grain - Answers - area in a metal where the atoms have the same orientation
Smaller Grain= - Answers - stronger and less ductile-rapid solidification gives smaller
grains
Crystalline - Answers - material where the atoms are in a 3D pattern-most metals are
crystalline
Amorphus - Answers - Material where the atoms are not in a 3D pattern-most glass is
amorphus
anisotropy - Answers - properties vary with direction-the crystalline nature of metals
causes their properties to be anisotropic
3 Common Crystal Structures in Metals - Answers - Face Centered Cubic, Body
Centered Cubic, Hexagonal Close Packed-most metals only exist in one crystal
ANSWERS
Four Main Types of Engineering Materials - Answers - Metals, polymers, ceramics,
composites
2 Main Areas of Material Science - Answers - extractive material science and physical
material science
Extractive Material Science - Answers - Deals with removing raw material from the earth
and processing it into an engineering material
Physical Material Science - Answers - Deals with how the properities of materials are
altered by processing
3 Main Types of Material Properties - Answers - Physical, mechanical, chemical
Physical Properites - Answers - these are inherent to the material-Density, thermal
expansion, thermal conductivity, electrical conductivity
Mechanical Properties - Answers - how the material reacts or responds to an external
force-hardness, strength, ductility, toughness, impact strength, fatigue strength
Chemical Properties - Answers - how the material reacts with its environment-corrosion
resistance
Element - Answers - pure sucstance that can not be broken down into a simpler
substance-approximately two thirds of all elements are metallic
Atoms - Answers - smallest part of an element that retains the properties of the element
Atoms are made up of - Answers - protons, neutrons, electrons
Protons - Answers - in the nucleus, positive charge, approximately 1 AMU
Electrons - Answers - orbits the nucleus, negative charge, approximately 1/1837 AMU
Neutrons - Answers - in the nucleus, no charge, approximately 1 AMU
Atomic Bonding - Answers - occurs because the atoms are trying to get to their lowest
energy state-this is when they have full outer electron shells (valence shells)
Main Types of Atomic Bonding - Answers - Covalent, Ionic, Vander Walls, Metallic
, Covalent - Answers - one atom shares its valence electrons with another atom so each
have full valence electron shells
Ionic - Answers - one atom gives its valence electrons to another atom so each have full
valence electron shells-materials with ionic and covalent bonds are typically poor
electrical conductors because the electrons are held in fixed positions
Vander Walls - Answers - weak electrostatic bonds-important for thermoplastics
Metallic - Answers - "sea of electrons"-electrons move from atom to atom so each feels
it has a full valence shell-this makes metals good electrical conductors
States of Matter - Answers - Gas, liquid, solid
Gas - Answers - atoms do not have short range or long range order, shape and volume
are not fixed
Liquid - Answers - atoms have some short range order, volume is fixed, shape assumes
that of the container
Solid - Answers - atoms have long range order, shape and volume are both fixed
Solidification of Metals: 3 Stage Process - Answers - Step 1: Nucleation-two atoms that
are close together form a chemical bond
Step 2: Growth-additional atoms bond to the nuclei formed in stage one
Step 3: Formation of the Grain Boundaries-this occurs when grains of different
orientation intersect
Grain - Answers - area in a metal where the atoms have the same orientation
Smaller Grain= - Answers - stronger and less ductile-rapid solidification gives smaller
grains
Crystalline - Answers - material where the atoms are in a 3D pattern-most metals are
crystalline
Amorphus - Answers - Material where the atoms are not in a 3D pattern-most glass is
amorphus
anisotropy - Answers - properties vary with direction-the crystalline nature of metals
causes their properties to be anisotropic
3 Common Crystal Structures in Metals - Answers - Face Centered Cubic, Body
Centered Cubic, Hexagonal Close Packed-most metals only exist in one crystal
