Honors Chemistry Ch. 6
non-polar covalent
a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge.
chemical bond
a mutual electrical attraction between the nuclei and the valence electrons of different atoms that binds them together. The attraction forces that holds atoms or ions together.
molecule
neutral group of atoms held together by covalent bonds
describe the arrangement of ions in crystals
"in an ionic crystal, even a slight shift of one row of ions relative to another causes a large buildup of repulsive forces. These forces makeit difficult for one layer to move relative to another, causing ionic compounds to be hard. If one layer is moved however, the repulsive forces make the layers part completely, causing ionic compounds to be brittle. In these solid state, the ions cannot move so the compounds are not electrical conductors. In the molten state, ionic compounds are electrical conductors because the ions can move freely to carry electrical current (lab we did in class proved this)"
Compare and Contrast Ionic and Molecular Compounds
- Molecular basic unit-molecule, chemical formula is a molecular formula, can be any of the three states of matter, has covalent bonding (non metal and non-mental electron sharing) - Ionic basic unit is an ion array crystal lattice, chemical formula-formula unit (smallest form of a compound), ionic bond between nonmetal and metal (electrostatic attraction - Comparison electrostatic forces are stronger than covalent bonds which accounts fo the difference in strength of attraction Ionic compounds have higher mp and bp and are harder than molecular compounds because the forces of attraction between molecules and require less energy to break
compare the properties of metals to those of ionic and molecular compounds
-metals bond with each other in metallic bonding -there is no basic unit because there is a metallic lattice and it has no crystal formula -the range for melting points and boiling points range all over -they are highly conductive -mostly solid in their standard state molecular and ionic compounds earlier
Relationships among potential energy, distance between approaching atoms, bond length, and bond energy
Bond length is determined by the position of lowest potential energy. Bond energy is the energy required to break a chemical bond and form neutral, isolated atoms, and energy increases when the nuclei of the two atoms get close to each other.
explain why most bonding is neither purely ionic nor covalent
Bonding is rarely purely ionic or covalent because it falls in-between these two extremes, depending on how strongly the atoms of each element attract electrons.
Describe dipole-dipole forces, hydrogen bonding, induced dipoles, and London dispersions forces and their effects on properties, specifically melting and boiling points.
Dipoles are created by an equal but opposite charge separated by a short distance. Dipole-dipole forces are are the short range forces of attraction between polar molecules. Hydrogen bonding is when H bonded to highly electronegative aim and is attracted to a lone pair on an electronegative atom in a nearby molecule (water is most important example). Hydrogen bonds contribute to water's high melting point and boiling point. London dispersion forces (act on all molecules, polar and non polar) are attractions resulting from the constant motion of electrons creating instantaneous dipoles.
describe the electron sea model of metallic bonding and why metals are such good electrical conductors
Electrons are tied down in covalent and ionic bonds. In metallic bonds, the electrons are highly mobile. The metallic bond model when mobile electrons are delocalized and form a sea of electrons around metal atoms. The electron clouds overlap which gives the delocalized electrons freedom to roam about the container. This property allows for metals high conductivity.
Explain hybridization theory and its relationship to molecular geometry; hybridization involved in CH4
Hybridization is the mixing of 2 or more atomic orbitals of similar energy on the same atom to produce new hybrid orbitals of the same energy. (Example: 2s +2p becomes 2sp3) When used in Carbon, it allows for it to have four open spots for bonding by combining the orbitals for the second (outermost) energy shell. She said we don't have to know too much just that it spreads out one single orbital (sp3) and it is imperative to the structure of Carbon.
classify bonding type according to electronegativity differences
Ionic- 1.7-3.3 (50-100% ionic character) Polar Covalent- 0.3-1.7 ( 5-50% ionic character) Non-polar covalent- 0-0.3 (0-5% ionic character)
lattice energy and its significance
Lattice energy is the energy release when one mole of an ionic crystalline compound is formed from gaseous ions. Chemists compare bond strengths in ionic compounds by comparing the amount of energy released when separated ions in a gas come together to form a crystalline solid (lattice energy)
explain why metals are malleable and ductile but ionic compounded are not
Metals are malleable and ductile because the metal atoms can slide past each other easily without encountering resistance or breaking bonds, while ionic compounds have a rigid structure, which will break if the ionic lattices try to slide past each other.
compare the distinctive properties of ionic and molecular compounds
Molecules relatively low mp/bp weak or no conductivity can be any of the three states of matter at standard state Ionic compounds relatively high mp/bp brittle it is conductive if aqueous or molten, it is a good electrolyte standard state-crystalline solid
explain why most atoms form chemical bonds; which elements do not, why?
Most atoms form chemical bonds because the atoms were not stable at an independent state. So they bond with other atoms. The noble gases do not form because they are stable.
why resonance structures are used to represent some molecules
Resonance structures show that one Lewis structure cannot correctly represent the location of electrons in a bond. Resonance structures show delocalized electrons, while Lewis structures depict electrons in a definite location
Explain VSPER theory
States that repulsion between the sets of valence electrons (shared pairs or lone pairs) causes them to be oriented as far apart as possible. V- valence S- shell P-pair E-electrons R- repulsion
describe how a compound containing a polyatomic ion involves both ionic and covalent bonding
The atoms in polyatomic ions are held together covalently, but the polyatomic ions combine with ions of opposite charge to form ionic compounds
describe the affect of multiple bonds on bond length and bond energy
The more bonds, the shorter and stronger. Single bonds are the weakest and longest
predict the shapes of molecules and polyatomic ions using VSPER theory; list three things that affect the shapes of molecules
There's a chart in the book that shows all of the shapes of molecules. Essentially, the number of bonds to a common atom is the shape (3-trigonal planar) etc. However, when electron pairs are left alone, that's when things get complicated and the shapes can become bent. The number of bonds, lone electron pairs, and intermolecular forces affect the shapes of molecules (I'm pretty sure that's right)
covalent bond
chemical bonding that results from the sharing of valence electrons between two atoms. non-metals to non-metals
Octet Rule
compounds tend to form so that each atom (by gaining, losing, or sharing electrons) had an octet of valence electrons or, and the config. of a noble gas.
describe the difference in electron interaction in the difference kinds of bonds
covalent- sharing electrons ionic- transferring electrons (one atom gains, one atom loses) metallic- attraction of "sea" of electrons
explain what determines molecular polarity
electronegativity difference and molecular geometry or unshared electron pairs
polar covalent
is a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons
Lewis structures.
know it.
metallic bond
results from the attraction between metal atoms and the surrounding "sea" of electrons. metal to metal
ionic bond
results from the electrostatic attraction between cations and anions. metal to non-metals
molecular formula
shows number of each kind of atom in a molecule
