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22 Cards in this Set
- Front
- Back
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ionic bonding |
involves the transfer of electrons and is usually observed when a metal bonds with a nonmetal |
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covalent bonds |
involve the sharing of electrons and is usually observed when a nonmetal bonds to a nonmetal |
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metallic bonding |
involves electron pooling and occurs when a metal bonds to another metal |
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Lewis Electron Dot Symbols |
Notethe A-group number, which gives the number of valence electrons. Placeone dot at a time on each of the four sides of the element symbol. Keepadding dots, pairing them, until all are used up. |
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Lewis Symbols and Bonding (metals) |
For ametal, the total number of dots in the Lewis symbol is the number of electrons the atom loses toform a cation. |
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Lewis Symbols and Bonding (nonmetals) |
For anonmetal, the number of unpaired dots equals - the number of electrons the atom gains to form an anion - orthe number it shares to form covalent bonds. |
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octet rule |
statesthat when atoms bond, they lose, gain, or share electrons to attain a filledouter level of 8 electrons (or2, for H and Li). |
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the ionic bonding model |
Anionic bond is formed when a metal transfers electrons to a nonmetal to form ions, which attract each other to give asolid compound. Thetotal number of electrons lost by the metal atom(s) equals the total number ofelectrons gained by the nonmetal atoms. |
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lattice energy |
energyrequired to separate 1 mol of an ionic solid into gaseous ions. affected by ionic size and ionic charge decreases down groups on periodic table increases as ionic charge increases |
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properties of ionic compounds |
tend to be hard,rigid, and brittle, with high melting points. do not conductelectricity in the solid state. Inthe solid state, the ions are fixed in place in the lattice and do not move. conduct electricitywhen melted or dissolved. Inthe liquid state or in solution, the ions are free to move and carry a current. |
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shared pair (bonding pair) |
Atomsshare electrons to achieve a full outer level of electrons. The sharedelectrons are called a sharedpair or bondingpair |
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unshared pair (lone pair) |
Anouter-level electron pair that is not involved in bonding |
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bond order |
the number of electron pairs being shared by a given pair of atoms |
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bond energy (BE) |
theenergy needed to overcome the attraction between the nuclei and the sharedelectrons. The stronger the bond the higher the bond energy. |
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bond length |
distance between the nuclei of the bonded atoms |
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Trendsin bond order, energy, and length |
For agiven pair of atoms, a higherbond order results in a shorterbond length and higherbond energy. For agiven pair of atoms, a shorter bond is a stronger bond. Bondlength increases down a group in the periodic table and decreases across the period. Bond energy shows the opposite trend |
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deltaH rxn |
= EdeltaH°reactant bonds broken+ EdeltaH°product bonds formed |
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polar covalent bond |
Acovalent bond in which the shared electron pair is not shared equally, butremains closer to one atom than the other |
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electronegativity |
Theability of an atom in a covalent bond to attract the shared electron pair iscalled |
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trends in electronegativity |
Themost electronegative element is fluorine. Ingeneral electronegativity decreases down a group as atomic size increases. Nonmetalsare more electronegative than metals. |
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Electronegativityand Oxidation Numbers |
The more electronegative atom isassigned all the shared electrons. The less electronegative atom isassigned none of the shared electrons. Each atom in a bond is assigned all of its unshared electrons O.N. = # of valence e––(# of shared e- + # of unshared e-) |
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depicting polar bonds |
Theunequal sharing of electrons can be depicted by a polar arrow. The head of thearrow points to the moreelectronegative element. |
