Topic 4: Bonding Flashcards
Positive and negative ions are known respectively as…
Cations and anions
Ionic bonding is only between what types of elements?
A bond between a metal and nonmetal
What formation and charge does the electrostatic attraction of an ionic bond create?
Neutral lattice
Ionic charge corresponds to…
Group number
Why does the lattice form in an ionic bond?
Opposite charges hold the ions together, so each ion is surrounded by six other ions with the opposite charge
What is the most stable arrangement in an ionic lattice?
Cation and anions are as close as possible to maximize attraction while minimizing repulsion
Under normal conditions, ionic compounds are usually in what state and what structure?
Solid, lattice
Lattice structures can explain…
ionic compounds’ physical properties
What are four specific physical properties of ionic compounds?
Volatility, melting point, electrical conductivity, solubility
What is volatility? What is the typical volatility of an ionic compound?
The tendency of a substance to vaporize. Ionic compounds are non volatile due to strong bonds, so room temp. cannot break them
What is the melting point for most ionic compounds generally?
High, due to strong bonds and the fact that they are solid at room temp
How conductive are ionic compounds?
As solids, not conductive. However, melted ionic compounds and aqueous ionic solutions are conductive because the ions are free to move
What is the solubility for ionic compounds?
Soluble in polar solvents, but some are insoluble
What is a giant covalent structure? What are some of its properties?
A covalent molecule w/ many nonmetal atoms. Usually giant regular lattices, very strong due to many bonds, high melting point, vary in conductivity
What are simple covalent structures? What state is it usually found in?
Only a few atoms held together by strong covalent bonds. Usually liquid or gases due to weak intermolecular forces
Covalent bonds are formed through____, usually between_____ and ____ atoms
sharing e-, nonmetal-nonmetal atoms
What are some exceptions to the octet rule?
Beryllium and Boron, as well as period 3 elements
What is molecular geometry?
Arrangement of atoms in space, position of e- in outer shell for the least repulsion
what does the number of electron domains in a covalent molecule determine?
The shape of the molecule due to repulsion
What are the three types of electron domain repulsion in order of least to greatest?
bonding pair-bonding < lone-bonding< lone-lone
What does VSEPR theory state and stand for?
Valence shell electron pair repulsion. Means that each atom will arrange itself in a covalent bond to minimize repulsion between domains.
What are the four steps to drawing a lewis diagram of a covalent molecule, including its bonds?
Sketch lewis diagram of each atom. Find total number of valence e-, and form single bonds between atoms. Each single bond subtracts 2e-. Then w/ remaining e-, add them to the outer atoms to achieve octet. W/ more leftover e-, add them to central atom or arrange them to form double/triple bonds until all atoms have an octet
What are the two conditions for a polar molecule?
Must have polar bonds and an asymmetrical distribution of partial charges across the molecule
What are four allotropes of carbon?
Diamond, graphite, C60 fullurenes, graphene
What are properties of graphite?
Hexagonal structure, weak van der waals forces between layers allow bonds to break easily as layers slide. Strong covalent bonds within layers but not between layers. Covalent layer lattice. Good conductivity due to delocalized e-.
What are properties of diamond?
Giant covalent structure, tetrahedral, no weak links, strong bonds, high melting point, poor conductivity bc no delocalized e-
What are properties of C60 fullurenes?
60 carbon atoms form a sphere w/ each atom covalently bonded, not a lattice. Strong, light semiconductor used in medicine to transport drugs in the body.
What is graphene, and what are its properties?
Hexagonally bonded allotrope of carbon that is one-atom thick. Very strong, light
What is the name of a molecule w/ 2 e- domains and no lone pairs? Bond angle?
linear, 180
What is the name of a molecule w/ 3 e- domains and no lone pairs? Bond angle?
Trigonal planar, 120
What is the name of a molecule w/ 3 e- domains including 1 lone pair? Bond angle?
Bent, <120
What is the name of a molecule w/ 4 e- domains and no lone pairs? Bond angle?
Tetrahedral, 109.5
What is the name of a molecule w/ 4 e- domains including 1 lone pair? Bond angle?
Trigonal bipyramidal, <109.5
What is the name of a molecule w/ 4 e- domains including 2 lone pairs? Bond angle?
Bent, <109.5
How does metallic bonding result?
It is the result of attraction between a lattice of ions and delocalized e-
What does the strength of metallic bonding depend on?
Ionic charge
Why are metals conductive and shiny?
Delocalized e- carry current and reflect light
Why are metals malleable and ductile?
Layers of metal can slide over each other without breaking
When are metals most/least conductive?
Most as aqueous or liquids, least as gases
What is an alloy?
Mixture of different metals melted and cooled
Why do alloys have enhanced properties?
Adding other metals alters the original metals’ properties
Why is alloy production possible?
Delocalized e- are nondirectional, and the lattice can accommodate different sized ions
Why are alloys stronger than pure metals?
Different ions disturb regular network of cations, so it is harder for the layers to slide
What is the difference between intermolecular and intramolecular forces?
Intermolecular=between molecules. Intra=between atoms
What are the three types of intermolecular forces in order of weakest to strongest?
London dispersion/van der waal, Dipole-diploe, hydrogen bonds
What are London dispersion forces?
Temporary attractions created by random clusters of e- that induce temporary dipoles. Causes nonpolar substances to condense in low temperatures
What are dipole dipole forces?
When a + end of a polar molecule attracts the - end of another polar molecule. Molecules must be close together, like in a liquid
What are hydrogen bonds?
attraction between a slightly positive H on one molecule and a slightly negative atom on another molecule. When the atom is F, O, or N, it is particularly strong since their electronegativity is high
