Chapter 6 - Chemical Bonding Flashcards
(24 cards)
Why do atoms form chemical bonds?
They want to decrease their potential energy
What is an ionic bond?
Chemical bonding that results from the electrical attraction between cations and anions
Electrons transferred
What is covalent bond and what are the two types?
A bond that results from the sharing from two atoms
Polar-unequal attraction
Nonpolar-equal attraction
What are the electronegativity difference cutoffs for the different bonds?
Nonpolar covalent (0.0-0.3) Polar covalent (0.4-1.7) Ionic (1.8-3.3)
What is a chemical bond?
Mutual chemical attraction between the nuclei and valence electrons of different atoms that binds the atoms together
What is a molecule?
A neutral group of atoms that are held together by covalent bonds
What is a molecular compound?
A chemical compound whose simplest units are molecules
Ex:
H2O
O2
What is a chemical formula?
It indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts
Gives composition of a compound
Both ionic and covalent
What is a molecular formula?
The type and numbers of atoms combined in a single molecule of a molecular compound
How does potential energy change as atoms get closer and farther?
Very close and very far- high
Decrease as it approaches a distance where forces are =
What is bond length?
The distance of two atoms at their minimum potential energy
What is bond energy?
The energy required to break a chemical bond and form neutral isolated atoms
What is the octet rule?
Chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of eight electrons in its highest energy level
What are the three exceptions to the octet rule?
Hydrogen only wants two
Boron only wants 6 (it had 3 valence)
Main-group elements in period three and up can form bonds with expanded valence (more than 8 electrons) like sulfur
What is electron dot notation?
An electron-configuration in which only the valence electrons are shown (as dots)
What are Lewis structures?
Formulas in which atomic symbols represent nuclei and inner-shell electrons, dot-pairs or dashes represent electron pairs in covalent bonds and dots adjacent to only one atomic symbol represent unshared electrons
What is a lone pair?
An unshared pair of electrons
What is a structural formula?
It indicates the kind, number, and arrangement of bonds, but not the unshared pairs pf electrons
What is a single/double/triple bond made of?
One/two/three pairs of electrons
What are the four steps to making a Lewis structure?
Write each element, write valence electrons, write electron-dot for each, Carbon is always central (or least electronegative) but never Hydogen, add unshared pairs until each has eight
For what three elements is a double bond common?
Carbon, nitrogen, oxygen
What is resonance?
It refers to the bonding in molecules or ions that cannot be correctly represented by a single Lewis structure
What are resonance structures or resonance hybrids and what goes between them?
The multiple valid Lewis structures for a given molecule or atom, double headed arrow
What is formal charge (and formula)?
The difference between the number of valance electrons on the free atom and the number of valence electrons assigned to the atom in the molecule
(# of valence) - (number of bonds) - (number of unshared/non-bonded)
