Mechanical Properties & Reactivity

Review BCC → Body-Centered-Cubic 3 most common type of Crystalline Structures FCC → Face-Centered-Cubic HCP → Hexagonal-Close-Packed Less packed, less malleable or ductile materials

Imperfections → (3 to 5 minute to list Imperfections that you know of) Are identified as impurities & disruptions in patterns of atoms. Several types of Imperfections are: Point Defect Line Defect Interfacial Defect Point Defect (3)→ Occurs at a specific point within the crystal. Definitions

1 st - Vacancies → Occur when an atom is missing & there is a void in the crystal. 2 nd - Interstitial Point Defect → Occur when extra atoms are inserted into the crystal lattice between normally occurring particles. 3 rd - Substitutional Point Defect → When a different type of atom substitutes for the usual one within the crystal lattice. Definitions

What Imperfections Does A, B & C Represent?

Line Defects (Dislocation) → Are regions within crystals when the atoms do not fit one right after another.  Move around when a piece of metal is bent, beaten or rolled  Causes metal to become harder Definitions

Example of a line Defect in a Crystal

Interfacial (defect) → Where 2 surfaces or planes meet. Grain Boundaries: More grain boundaries the less workable the material is. Definitions

Properties → Characteristics which allow us to identify and distinguish one material from another and predict the behavior of a material. Physical Properties → Characteristics possessed by materials which can be used to help identify the material and how it might act. Electrical conductivity, Thermal expansion, Magnetic, Melting point, Density, ability to transmit light. AND Definitions

Elasticity → The ability to return to the original shape after being deformed by stress. Ex: rubber band Plasticity → Material will remain in its new position when the distorting force is removed. Ex: piece of clay Definitions

Brittle → The material will break when forced to undergo small deformations. Hardness → The ability to resist indentation. Rockwell scale – indentation hardness (no units) Toughness → The ability to absorb energy before it fractures. Definitions

Mechanical Stress: 4 most common are → Tension → A stress that attempts to pull material apart. Tensile Strength → is the stress ( Newtons/m² or psi ) at which a sample of solid material will break from tension. Compression → The force that tries to compress or push together the particles of a material. Definitions

Mechanical Stress: 4 most common are → Shear → A stress that results when there are forces in opposite directions but not lined up. Torsion → A stress resulting from a twist placed on a material. Definitions

What Mechanical Stress is this? Compression

What Property is this? Hardness

What Mechanical Stress is this? Shear

What Mechanical Stress is this? Torsion

Destructive Test → Testing that most likely damages or destroys the tested item. ◦ Flammability test ◦ Ramming a car for air bag test ◦ Mechanical Stress testing (??) ◦ Taste Testing ◦ Etc…. Material Testing Methods

Non - Destructive Test → Testing that doesn’t damage or destroy the tested item. ◦ X-ray test ◦ Magnetic imaging test ◦ Dye Penetration test ◦ Ultrasonic Imaging ◦ Mechanical Stress testing (??) ◦ Etc… Material Testing Methods

Let’s start Paper Clip Lab.

Paper Clip Lab Review

Paper Clip Lab

Standard Deviation → The measure of the spread of data values.

Paper Clip Lab Review What type of testing did we do on the paper clips? Why did we get different results between paper clips and teams? What would your paper clip guarantee be? Why? Calculate the Mean, Mode, Median, Range for both your “A” and “B” paper clip data. Find Standard Deviation for your team’s data.

Applies to normal distributions Almost all data will fall within three standard deviations of the mean The Empirical Rule or 3 sigma Rule

68% of the observations fall within 1 standard deviation of the mean. 95% of the observations fall within 2 standard deviations of the mean. 99.7% of the observations fall within 3 standard deviations of the mean. If the data are normally distributed:

Data from a sample of a larger population

Data Elements s s = = %

Data Elements 2s s = = %

Density → Weight per unit volume ◦ Standard volume in English System is a cubic foot (ft³) ◦ Standard volume in Metric System is a cubic centimeter (cm³) Specific Gravity → How many times heavier one type of material is than an equal volume of water. (Temperature & pressure need to be considered) What is the specific gravity of water? Density 1

Properties (review)→ Characteristics which allow us to identify and distinguish one material from another and predict the behavior of a material. Chemical Properties → Characteristics that indicates how a material will interact with other materials in its environment. rusting, wood rotting, cracking of rubber tires due to ozone AND Definitions

Reactivity → A measurement of the relative ease by which an element will undergo an oxidation-reduction. Chemical Property

Oxidation → The process by which an atom becomes positively charged by losing one or more electrons. Reduction → The process by which a positive ion becomes a neutral atom by gaining one or more electrons. Reactivity

Lab on Thursday

What 3 metals can be found in pure form → Gold Silver Copper How do we get the other metals in their pure form → 1 st : Mine Ore → 2 nd : Concentrate Ore to oxide → 3 rd : Break metal & oxygen ionic bond (reduction) → 4 th : Metallic ions are now metal atoms. How do we Get Metals?

Reactivity Diagram

Example: What happens when Zinc is added to iron oxide and heated? Zinc atom gives its electrons to the iron ion and becomes a Zinc ion. (It is oxidized.) Iron ion in the iron oxide accepts electrons from Zinc to become an iron atom. (It is reduced.)

Extraction of phosphorus

Weight % of the most Common Elements in the Earth’s Crust

What are three elements that are magnetic? (In Alphabetical order) 1. ? 2. ? 3. ?