Atomic and Electronic Structure Quiz
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Questions and Answers

What is the primary purpose of hardness testing in materials science?

To measure the resistance of a metal to permanent plastic deformation.

What are the three primary subatomic particles that make up an atom?

Electrons, protons, and neutrons.

Describe the key difference between ductile and brittle fractures.

Ductile fractures involve significant plastic deformation, while brittle fractures exhibit little or no plastic deformation.

Why are stable elements generally non-reactive?

<p>Stable elements have completely filled valence shells, reducing their tendency to participate in chemical reactions.</p> Signup and view all the answers

What is a unique feature of the Vickers hardness test?

<p>It uses a square pyramid indenter and measures the length of the diagonal of the indentation.</p> Signup and view all the answers

How does crack propagation occur in materials?

<p>Cracks propagate due to the sharpness of the crack tip, and in plastic materials, the tip blunts with deformation.</p> Signup and view all the answers

How does electronegativity change across the periodic table?

<p>Electronegativity increases from left to right and from bottom to top.</p> Signup and view all the answers

Define ionic bonding in terms of electron behavior.

<p>Ionic bonding involves the transfer of electrons from metals to non-metals, resulting in the formation of charged ions.</p> Signup and view all the answers

What materials are commonly tested using the Rockwell hardness method, and how does it differ for those materials?

<p>Rockwell B uses a ball indenter for soft materials, while Rockwell C employs a diamond cone for harder materials.</p> Signup and view all the answers

What is the purpose of material testing?

<p>Material testing determines the physical and mechanical properties of materials under various conditions.</p> Signup and view all the answers

What does the tensile testing method measure?

<p>Tensile testing measures the maximum stress that can be applied to material before it permanently deforms.</p> Signup and view all the answers

What role do valence electrons play in covalent bonding?

<p>In covalent bonding, atoms with similar electronegativities share their valence electrons.</p> Signup and view all the answers

What is meant by discrete energy states of electrons?

<p>Discrete energy states refer to the specific energy levels that electrons can occupy in an atom.</p> Signup and view all the answers

What is the primary purpose of conducting torsion tests on products?

<p>To simulate real life service conditions, check product quality, verify designs, and ensure proper manufacturing techniques.</p> Signup and view all the answers

Name two types of torsion testing methods.

<p>Torsion Only and Axial-Torsion.</p> Signup and view all the answers

What defines failure testing in torsion tests?

<p>Twisting the specimen until it either physically breaks or shows a kink/defect.</p> Signup and view all the answers

Explain proof testing in the context of torsion.

<p>Proof testing involves applying a torsional load and holding it for a fixed amount of time.</p> Signup and view all the answers

List at least three materials commonly used in torsion testing.

<p>Metals, plastics, and composites.</p> Signup and view all the answers

What is flexural strength?

<p>Flexural strength is the stress required to fracture a specimen in a bend test.</p> Signup and view all the answers

How is flexural modulus calculated?

<p>It is calculated from the results of a bend test, providing the slope of the stress-deflection curve.</p> Signup and view all the answers

What is the purpose of functional testing in torsion tests?

<p>To test complete assemblies or products to verify their performance under torsional loads.</p> Signup and view all the answers

What is elastic strain energy and when is it released?

<p>Elastic strain energy is the energy stored in a material as it is elastically deformed, and it is released when a crack propagates.</p> Signup and view all the answers

Describe the characteristics of ductile fracture.

<p>Ductile fracture involves plastic deformation prior to fracture and is characterized by extensive necking and a stable crack propagation process.</p> Signup and view all the answers

List the key steps in the evolution of moderately ductile failure.

<p>The key steps are necking, void nucleation, coalescence of cavities, crack propagation, and eventual fracture.</p> Signup and view all the answers

What distinguishes brittle fracture from ductile fracture?

<p>Brittle fracture occurs with little to no plastic deformation and propagates rapidly and unstably, whereas ductile fracture involves significant plasticity and stable propagation.</p> Signup and view all the answers

What mechanisms can lead to intergranular fracture?

<p>Intergranular fracture can be caused by elemental depletion at grain boundaries or weakening due to chemical attack or oxidation.</p> Signup and view all the answers

How does transgranular fracture occur in brittle materials?

<p>Transgranular fracture occurs through the repeated breaking of atomic bonds along specific planes within the grains of brittle materials.</p> Signup and view all the answers

Explain the relationship studied in fracture mechanics.

<p>Fracture mechanics studies the relationships between material properties, stress levels, crack-producing flaws, and crack propagation mechanisms.</p> Signup and view all the answers

Define toughness and how it differs from fracture toughness.

<p>Toughness is a material's ability to absorb energy without fracturing, while fracture toughness specifically measures a material's resistance to crack propagation.</p> Signup and view all the answers

What does the Charpy impact test measure?

<p>It measures the energy absorbed by a standard notched specimen while breaking under an impact load.</p> Signup and view all the answers

How does the Izod impact test differ from the Charpy impact test?

<p>The Izod test uses a cantilevered beam configuration to hold the sample, while Charpy uses a three-point bending configuration.</p> Signup and view all the answers

What is the purpose of notching a specimen in impact tests?

<p>Notching a specimen helps in determining the impact energy and notch sensitivity.</p> Signup and view all the answers

Why is the drop-weight impact test also known as the Pellini test?

<p>It is named after the method's origin, given by its developer, which is used to evaluate impact effects without measuring energy absorbed.</p> Signup and view all the answers

What forms of failure are considered in the drop-weight impact test?

<p>Fracture, deformation, or the formation of a crack can all be considered as failure.</p> Signup and view all the answers

What is the common use of the Charpy impact test in engineering materials?

<p>It is commonly used as an economical quality control method to determine notch sensitivity and impact toughness.</p> Signup and view all the answers

What is the role of energy measurement in impact tests like Charpy and Izod?

<p>In these tests, the energy measurement indicates the material's toughness and its ability to withstand impacts.</p> Signup and view all the answers

What types of materials can be evaluated using the Charpy impact test?

<p>The Charpy impact test can evaluate metals, composites, ceramics, and polymers.</p> Signup and view all the answers

What is the key distinction between dynamic tear testing and drop-weight impact testing?

<p>Dynamic tear testing is for specimens less than 5/8&quot; thick, while drop-weight impact testing is for thicker specimens.</p> Signup and view all the answers

What is the main goal of conducting a fatigue test?

<p>To determine the lifespan a material can endure under cyclic loading.</p> Signup and view all the answers

How does a fatigue test machine operate during a fatigue test?

<p>It applies a pre-determined stress to the sample, then unloads either to zero load or an opposite load.</p> Signup and view all the answers

What are the key factors influencing corrosion in metallic components?

<p>The metal composition, protective treatments, and the surrounding environment.</p> Signup and view all the answers

Define fatigue life in the context of material testing.

<p>Fatigue life is the total number of cycles a material can endure under a given loading scheme.</p> Signup and view all the answers

What is typically sought after in fatigue strength testing?

<p>Fatigue strength and crack resistance are commonly sought values.</p> Signup and view all the answers

What loading conditions are commonly used in cyclic fatigue tests?

<p>Loading conditions include tension, compression, bending, and torsion.</p> Signup and view all the answers

What happens to a sample during a fatigue test at the predetermined load?

<p>The sample undergoes repeated cycles of loading and unloading until it fails or reaches the test limit.</p> Signup and view all the answers

Flashcards

Atomic Structure Components

Atoms are composed of electrons, protons, and neutrons.

Electron Energy Levels

Electrons occupy specific energy levels within an atom.

Valence Electrons

Electrons in the outermost shell of an atom, determining its reactivity.

Electronegativity Trend

Electronegativity increases going right across the periodic table and upward.

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Ionic Bonding

Chemical bond formed by the transfer of electrons between atoms.

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Covalent Bonding

Chemical bond formed by the sharing of electrons between atoms.

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Destructive Material Testing

Evaluation of material properties that permanently damages the sample.

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Tensile Testing

Material testing method to determine the strength and elongation of a material under tension.

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Torsion Test

A test to simulate real-life conditions, check product quality, and verify manufacturing techniques by applying rotational motion to a material or product.

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Torsion Test Types

Types include torsion-only, axial-torsion (combining twisting and pulling/pushing forces), failure (testing until break), proof (holding a load for time), and functional testing (testing complete assemblies).

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Torsion Materials

Materials like metals, plastics, polymers, composites, and ceramics can be tested in torsion. They often include products like fasteners, rods, beams, tubes, and wires.

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Bend Test

A test method for measuring material resistance to bending under a static load, applied to a central bar supported on both ends.

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Flexural Strength

The stress level at which a material breaks in a bend test. Also called modulus of rupture or bend strength.

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Flexural Modulus

The elasticity calculated from a bend test, showing the material's stiffness during bending.

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Axial-Torsion

A torsion test applying both twisting and pulling/pushing forces, simulating a more complex load condition.

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Failure Testing

A torsion test method that continues twisting a product until it breaks, whether physically or with defects.

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Hardness Testing

Measuring a metal's resistance to permanent deformation by forcing an indenter into its surface.

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Brinell Hardness Test

A hardness test using a ball indenter; used for softer materials.

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Vickers Hardness Test

A hardness test using a square pyramid indenter; accurate results, measures diagonal length of indention

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Ductile Fracture

Fracture in metals, accompanied by considerable plastic deformation.

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Brittle Fracture

Fracture in materials, with little or no plastic deformation, often sudden.

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Elastic Strain Energy

Energy stored within a material when it is elastically deformed. This energy is released when a crack propagates, as creating new surfaces requires energy.

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Transgranular Fracture

Fracture where the crack propagates through the grains of the material. It occurs through the breaking of atomic bonds along specific planes, often in brittle crystalline materials.

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Intergranular Fracture

Fracture that occurs along the grain boundaries of a material. It's often caused by elemental depletion, chemical attack, or embrittlement at the boundaries.

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Fracture Mechanics

The study of how material properties, stress levels, crack flaws, and crack propagation mechanisms interact to cause fracture.

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Toughness

A material's ability to absorb energy before fracturing.

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Fracture Toughness

A material's resistance to crack propagation under stress. It is a measure of the ability of a material to tolerate a crack without catastrophic failure.

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Charpy Impact Test

Measures the energy absorbed by a notched specimen while breaking under impact load. It's a common test used to determine impact toughness and notch sensitivity of materials like metals, composites, ceramics, and polymers.

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Izod Impact Test

Similar to Charpy, but uses a cantilevered specimen setup. Measures impact resistance by calculating the energy absorbed after a pivoting arm hits the sample.

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Drop-Weight Impact Test

Uses a weighted object dropped onto a specimen. Measures impact resistance, but only focuses on pass/fail results as energy absorbed is difficult to calculate.

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Dynamic Tear Test

Very similar to the drop-weight test, but with an emphasis on the tear response of the material.

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What test determines impact energy and notch sensitivity?

The Charpy Impact Test is most used to determine both the relative impact energy and notch sensitivity of a material.

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What does the Izod test differ from the Charpy test?

The Izod test uses a cantilevered beam arrangement of the specimen, unlike the Charpy test's three-point bending configuration.

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What is the Pelini test?

The Pelini test is another name for the drop-weight impact test.

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Why is the drop-weight impact test pass/fail?

The drop-weight test doesn't determine the energy absorbed by the specimen, only if it passes or fails based on fracture, deformation, or crack formation.

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Fatigue Test Purpose

To determine a material's lifespan under repeated loading and unloading, assess its fatigue strength and crack resistance.

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Fatigue Test Types

Cyclic fatigue tests involve repeated loading and unloading in different stress modes, including tension, compression, bending, torsion, and combinations of these stresses.

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What is Fatigue Life?

The total number of cycles a material can withstand under a specific loading scheme before failure.

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Corrosion

The slow and continuous deterioration of metallic components due to chemical or electrochemical attack.

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Corrosion Factors

Three factors govern corrosion: the type of metal, the protective treatment on its surface, and the surrounding environment.

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Corrosion Prevention

Protecting materials from corrosion can involve careful material selection, surface treatments like coatings, and control of the environment to minimize corrosion.

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Study Notes

Atomic Structure

  • Atoms are composed of electrons, neutrons and protons
  • Electron mass = 9.11 × 10−31 kg
  • Neutron and proton mass = 1.67 × 10−27 kg
  • Atomic number = number of protons in the nucleus of an atom
  • Atomic mass unit (amu) = 1/12 the mass of a 12C atom
  • Atomic weight = weight of 6.022 x 1023 molecules or atoms (amu/atom = 1 g/mol)

Electronic Structure

  • Electrons exhibit wave-like and particle-like properties
  • Electrons occupy orbitals defined by probability
  • Orbitals exist at discrete energy levels determined by quantum numbers
  • Principal quantum number (n) indicates energy level (shell) K, L, M, N, O etc.
  • Subsidiary quantum number (l) refers to orbitals (s, p, d, f)
  • Magnetic quantum number (ml) indicates orientation of orbital (1, 3, 5, 7)
  • Spin quantum number (ms) refers to spin (+1/2, -1/2)

Electron Configurations

  • Filled electron shells are more stable
  • Valence electrons are found in unfilled shells and play a major part in bonding and controlling the chemical properties of an element
  • Example: carbon (atomic number 6), electronic configuration 1s22s22p2 meaning 6 electrons in total

Survey of Elements

  • Most elements have incomplete outer electron shells.
  • Elements' stability and electron configuration are related.
  • Example: Hydrogen (1) 1s1, Helium (2) 1s2, Lithium (3) 1s22s1, Beryllium (4) 1s22s2, Boron (5) 1s22s22p1, Carbon (6) 1s22s22p2, Neon (10) 1s22s22p6

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Test your knowledge on atomic structure, electronic configurations, and the properties of electrons. This quiz covers the composition and behavior of atoms, including detailed characteristics of protons, neutrons, and electrons. It's perfect for students studying chemistry at any level.

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