Chapter 2 Atomic Structure and Interatomic Bonding Flashcards
What determines the properties of materials?
The properties of materials are determined by the bonds between atoms and their atomic arrangement.
What are the two models used to describe atomic structure?
The two models used to describe atomic structure are the Bohr model and the wave-mechanical model.
What is the Pauli Exclusion Principle?
The Pauli Exclusion Principle states that each electron state can hold no more than two electrons with opposite spins.
What are valence electrons?
Valence electrons are the electrons in the outermost shell of an atom and are most important in determining bonding and material properties.
How do elements achieve stable electron configurations?
Elements achieve stable electron configurations by gaining, losing, or sharing electrons to fill their outer shells, often attaining a configuration with 8 valence electrons (S²P⁶) like noble gases.
What is electronegativity?
Electronegativity is the tendency of an atom to attract an electron.
What are the differences between metals and non-metals in terms of electrons and electronegativity?
Metals have few electrons (≤3) in their outer shells, form cations by losing electrons, and have low electronegativities, while non-metals have ≥4 electrons in their outer shells, form anions by accepting electrons, and have high electronegativities.
Why do atoms bond with each other?
Atoms bond with each other to reduce their overall energy and become more stable.
What forces are involved in inter-atomic spacing?
Inter-atomic spacing is determined by the balance between attractive and repulsive forces.
What is the equilibrium position in terms of inter-atomic forces?
The equilibrium position (r₀) is the inter-atomic distance where the net force is zero (attractive force equals repulsive force), or when the overall energy is at a minimum (E₀).
What are the primary types of atomic bonds?
The primary types of atomic bonds are ionic, covalent, and metallic.
What are the secondary types of atomic bonds?
The secondary types of atomic bonds are Van der Waals bonds, which include fluctuating dipoles, induced dipoles and permanent dipoles as well as hydrogen bonds.
How does ionic bonding occur?
Ionic bonding occurs between electropositive (metallic) and electronegative (non-metallic) atoms through the transfer of electrons and the resulting electrostatic attraction between oppositely charged ions.
What are some characteristics of ionically bonded materials?
Ionically bonded materials tend to have high melting points, high hardness, are brittle, and are electrically and thermally insulative.
How does covalent bonding occur?
Covalent bonding occurs when atoms share electrons to achieve stable electron configurations. It typically occurs between atoms with small differences in electronegativity.
What is a characteristic of a covalent bond?
Covalent bonds are directional and can be very strong.
What is metallic bonding?
Metallic bonding occurs when valence electrons form a ‘sea’ of electrons that are free to move among positively charged ion cores.
What are some properties of metallic bonds?
Metallic bonds are non-directional and allow for ductility and electrical/thermal conductivity.
What are Van der Waals bonds based on?
Van der Waals bonds are based on atomic or molecular dipoles.
How does bond energy relate to melting temperature (Tm)?
Higher bond energy leads to a larger melting temperature.
How does bond energy relate to elastic modulus (E)?
Higher bond energy leads to a larger elastic modulus (stiffness).
How does bond energy relate to the thermal expansion coefficient (α)?
Smaller bond energy leads to a larger thermal expansion coefficient.
What type of bonding is found in brass?
Brass exhibits metallic bonding.
What type of bonding is found in rubber and nylon?
Rubber and nylon exhibit covalent bonding with some Van der Waals bonding.
