Chapter 2 Flashcards
What are the four properties that are determined my an atom’s electronic structure/configuration?
Chemical, electrical, thermal, optical
What are two wave-like characteristics?
- Electron position in terms of probability density
- Shape, size, orientation or probability density determined by quantum numbers
What happens to a metal atom during the ionization process? A nonmetal?
metal atom: donates electrons
nonmetal atom: accepts electrons
What is required for ionic bonding?
- positive and negative ions
- electron transfer
- ## large difference in electronegativity (X)
What are the different parts of the potential energy chart for ionic bonding?
- The net energy is repulsive and very rapidly goes to be attractive, then the net energy slowly gets less attractive as r increases
What difference in electronegativity is required for covalent bonding? Why?
Similar electronegativities to share electrons
What kinds of electrons are involved in covalent bonding?
Valence electrons– normally s and p orbitals are involved
What kind of hybrid orbitals can carbon form?
sp^3
In CH4, what kinds of orbitals are electrons shared in?
sp^3
How do electrons act in metallic bonding?
electrons delocalized to form electron clouds
What is the most common mixed bonding type?
Covalent-ionic mixed bonding
Where does secondary bonding come from?
Attractive forces between dipoles
What are the two different types of dipoles?
Fluctuating dipoles and permanent dipoles
What are examples of secondary bonding? (3)
- Liquid H2
- Liquid HCl
- polymer
How does bond length relate to melting temperature?
it has the largest bond length at the unstretched radius length and then it slowly gets closer to the axis
How does bond energy relate to the coefficient of thermal expansion?
the small bond energy, the larger coefficient of thermal expansion
What kind of bonding do ceramics have?
Ionic and covalent bonding
What kind of bonding do metals have?
metallic bonding
What kind of bonding do polymers have?
covalent and secondary
What are the properties of ceramic’s bonding energy?
high Tm- melting
large E- bonding E
small αl- coeff. of thermal expansion
What are the properties of metals’ bonding energy?
moderate Tm - melting
moderate E - bonding E
moderate αl- coeff. of thermal expansion
What are the properties of polymers’ bonding energy?
low Tm- melting
small E- bonding E
large αl- coeff. of thermal expansion
** the secondary bonding is responsible for most of the physical properties
What does the percent ionic character of a covalent-ionic mixed bond between two elements depend on?
Electronegativities
What kind of bonding do molecular solids have?
ver de waals
What kind of bonding do semi-metals have?
mixed covalent-metallic
what kind of bonding do intermetallic have?
mixed metallic-ionic
What’s an example of bonding affecting a material’s properties?
Diamond is a poor conductor or electricity but graphite is a good conductor
When some elements covalently bond, what kind of bonds do they form? For C, Si, and Ge
They from sp hybrid orbitals
What are two typical properties of nonmetals?
Electrical and thermal insulators
Do materials with high bonding energies typically have high or low melting temperature?
high melting temperatures
Why are covalently bonded materials generally less dense then ionically or metallically bonded ones?
Covalent bonds are directional in nature whereas metallic and ionic are not; when bonds are directional, the atoms cannot pack together in as dense a manner, yielding a lower mass density
What are the melting and boiling properties molecules like?
They are relatively low melting and boiling temperatures
