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62 Cards in this Set
- Front
- Back
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Ionic bonding |
Chemical bonding that results from the electrostatic attraction between cations and anions. Cations are former by metals losing their valence electrons and anions are formed by nonmetals gaining them. |
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The number of electrons lost or gained is determined by: |
Electron configuration (+periodicity). |
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Why do we have ionic bonds? |
Elements want noble gas configurations. |
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Polyatomic ions |
Ions that are made of more than one atom and which together experienced a loss or gain and therefore have a charge. |
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In normal conditions, ionic compounds are: |
Solids with lattice structures. |
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Tendency to form ions on periodic table |
Increasing tendency to form positive ion down the table. Increasing tendency to form negative ions down the table. |
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Electronegativity pattern |
Back (Definition) |
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Ionic electronegativity difference is |
1.8+ |
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Covalent bonding |
Formed by electrostatic attraction between shared pair of electrons of non metals. |
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Covalent bonding |
Formed by electrostatic attraction between shared pair of electrons of non metals. |
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Bonds |
More than a pair of electrons can be shared for multiple bonds. The more bonds the shorter. |
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More bonds are shorter bonds. Why? |
Stronger force of electrostatic attraction between bonded nuclei. Since there is more pulling power they’re brought together and therefore have shorter bonds. |
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When are they polar? |
When they are not symmetrically arranged. |
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What do covalent substances form? |
Crystalline solids |
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What are allotropes? |
Different forms of an element in the same physical state. Different bonding= different forms and properties. |
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Allotropes of carbon |
Graphite, diamond, fullerene. |
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Intermolecular forces |
Forced that exist between molecules. |
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The melting points of these forces.. |
Melting and boiling both involve separating particles by overcoming the forces between them. So the stronger the intermolecular forces the more energy will be required to do this and therefore higher melting points. |
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Hydrogen bonding |
A partially electrostatic attraction between a hydrogen atom which is bound to a more electronegative atom (O,N,F) and another atom with a lone pair of electrons. |
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Why O, N, F in hydrogen bonding? |
Very electronegative which make a strong dipole and they have small atomic radio. |
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Boiling points of hydrogen bondjng |
Very high due to it being the stronger intermolecular force of attraction. |
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Dipole dipole attractkon |
Polar molecular are attracted to each other by electrostatic forces. Permanent dipole due to permanent separation of charge within their bonds due to difference in electronegativity if bonded atoms. |
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Dative or coordinate bonds |
Both electrons come from the same atom. |
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London dispersion forces |
Temporary dipoles which occur as a result of electrons momentarily move to one end of the molecule. -Non polar molecules. |
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Order of boiling points of forces |
Ion yo ion, H bonds, dipole dipole, dispersion. |
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Molecular geometry: name, domains and bond angle: |
Linear, 2, 180. Trigonal planar, 3, 120. Tetrahedral, 4, 109.5. |
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Electron geometry: 2 bonds, 1 lone pair +molecular geometry, name and bond angle. |
Electron Geometry: trigonal planar, bent, <120 |
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Electron geometry: 3 bonds, 1 lone pair +name, molecular and bond angle |
Tetrahedral, trigonal pyramidal, <109.5 (107) |
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2 bonding, 2 lone pairs |
Tetrahedral, bent, <109.5 (104). |
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Trigonal pyramidal molecular geometry: |
3 bonds and 1 lone pair. |
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Metals |
Found on the left of periodic table. Usually lose electrons. Low ionization energy. |
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Delocalized electrons |
Electrons in a molecule, ion or solid metal not associate with a single atom or covalent bond. |
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Metallic bonding |
Type of chemical bonding that rises from the electrostatic attraction between the lattice of positive ions and delocalized electrons. |
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Dipoles |
If electrons spend more time with one atom than the other then they’re not equally shared. This occurs where there’s a difference in the electronegativities of the bonded atoms. |
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Why are metals good electricity conductors? |
The delocalized electrons are highly mobile and can move through the metal structure in response to an applied voltage. |
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How are they malleable and ductile? |
The movement of electrons is non directional (random) through the cation lattice so they’re not unduly disturbed by a change in the conformation of the metal through applied pressure. Or The positively charged metal nuclei are free to move with respect to each other hence the property. |
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Malleable |
Hammered into thin sheets |
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Ductile |
Made into wires |
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Melting points of ionic compounds: |
High because of the forces of electrostatic attraction between the ions in the lattice are strong and require high energy to break. |
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Ionic compounds are: (state of matter) |
Solids at room temperature and only melt at high temperatures. |
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Melting points of macromolecular or giant covalent: |
High as covalent bonds must be broken for these changes of state to occur. Also solid at room temperature. |
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Why do covalent substances have lower melting points then ionic? |
As the forces needed to be overcome to separate the molecules are relatively weak intermolecular forces. So manly covalent substances are liquid and gases at room temp. |
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Strength of intermolecular forces will increase with: |
Increasing molecular mass. The extent of polarity within the bonds. Stronger forces= higher melting points. |
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Which substances are conductive? |
Metallic, polar and molten or dissolved in water ionic substances. |
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Electronegativities of the bonded atoms cause what impact on dipoles? |
More electronegative atoms exerts a greater pulling power on the shared electrons, gaining more possession. |
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Which substances are not conductive? |
Non polar and solid ionic substances. |
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Formal dipole definition |
Covalent bonds having 2 separated opposite electric charges or poles. |
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Partially positive dipoles: |
Less electronegative atom |
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Partially negative diples |
More electronegative atom |
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Bonds are more polar when the electronegativity difference is higher. So, which is more polar H-F or H-Cl? |
H-F because F is more e.n. than Cl. |
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Electronegativity differences |
0= Non Polar Up to 1.8= Polar 1.8+= Ionic |
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When are polar molecules non polar? |
If the bonds have equal polarity and are arranged in symmetrical order they cancel out. |
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Electronegativity differences |
0= Non Polar Up to 1.8= Polar 1.8+= Ionic |
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Electron geometry: 2 bonds, 1 lone pair +molecular geometry, name and bond angle. |
Electron Geometry: trigonal planar, bent, <120 |
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Solid ionic compounds cannot conduct electricity because |
The ions are held in fixed positions |
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Graphite |
Covalently bonded hexagons, parallel layers with bond angle 120 and layers are held by vanderwaal forces to slide over each other |
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Graphite |
Covalently bonded hexagons, parallel layers with bond angle 120 and layers are held by vanderwaal forces to slide over each other |
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Diamond |
Covalently bonded tetrahedral |
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Graphite |
Covalently bonded hexagons, parallel layers with bond angle 120 and layers are held by vanderwaal forces to slide over each other |
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Diamond |
Covalently bonded tetrahedral |
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Fullerene |
Bonded in a sphere of 60 carbon atoms. Spherical cage |
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Macromolecule or Giant |
Some covalent substances form crystalline solids where all atoms are linked together by covalent bonds. The crystal is a single molecule with a repeating partern |
