Chapter 8 Flashcards
What is the octet rule?
When forming compounds, atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons (the octet rule).
What is formal charge?
Formal charge is the charge an atom would have if all of the electrons in a covalent bond were shared equally.
What is ionic bonding?
Between metals and nonmetals (except group 8A), involve electron transfer, very exothermic, one element readily gives up an electron (has a low ionization energy), another element readily gains an electron (has a high electron affinity).
What is covalent bonding?
In covalent bonds, atoms share electrons. Primarily nonmetals.
What is electronegativity?
Electronegativity is the ability of an atom in a molecule to attract electrons to itself.
What are the trends in electronegativity?
On the periodic table, electronegativity generally increases as you go from left to right across a period, from the bottom to the top of a group.
How to calculate dipole moment?
A dipole moment, µ, produced by two equal but opposite charges separated by a distance, r, is calculated: µ = q * d
What is the difference in ionic and covalent bonds
Ionic: complete electron transfer, i.e. metal + nonmetal
Covalent: electron pair sharing, i.e. two nonmetals
What are resonance structures used for?
We use multiple structures, resonance structures, to describe the molecule.
Are there ions with an odd number of electrons?
Though relatively rare and usually quite unstable and reactive, there are ions and molecules with an odd number of electrons.
Can there be ions with fewer than 8 valence electrons?
Elements in the second period before carbon can make stable compounds with fewer than eight electrons.
Can there be ions with greater than 8 valence electrons?
When an element is in periods 3 through 6, it can use d-orbitals to make more than four bonds and be hypervalent.
Bond enthalpy and bond length?
Multiple bonds are stronger than single bonds. As the number of bonds between two atoms increases, the bond length decreases.
What are the properties of bond enthalpies?
All bond enthalpies are positive as bond breaking is an endothermic process. These are averages over many compounds; not every bond for a pair of atoms has the same bond energy.
What is lattice energy?
This is a measure of how much stability results in arranging oppositely charged ions in an ionic solid. Defined as the energy required to completely separate one mole of a solid ionic compound into its gaseous ions.
What is the formula for lattice energy?
Lattice energy = Heat of formation - (Heat of atomization + Dissociation energy + Ionization energies + Electron affinities).
