Bonding and Structure Flashcards
What is ionic bonding?
The electrostatic attraction between positive and negative ions
What are giant ionic lattices?
It is a regular, repeated arrangement of ionic compound
Effect of structure and bonding of ionic compounds on - melting point?
The electrostatic attraction between anions and cations is very strong, so it takes a lot of energy to overcome. The greater the ionic charges the stronger the attraction
Effect of structure and bonding of ionic compounds on solubility?
The polarity of water makes it attracted to the anions and cations
Effect of structure and bonding of ionic compounds on electrical conductivity?
Ions can only conduct electricity when its ions are free to move (in a liquid/aqueous)
What is covalent bonding?
The electrostatic attraction between the shared pair of electrons and the nuclei of the bonded atoms
What is dative covalent bonding?
A covalent bond in which both of the electrons come from the same atom
What is average bond enthalpy?
measures the energy required to break a bond
How is the shape of molecules determined (electron pair repulsion etc.)?
The electron pairs repel from each other so are situated at furthest distance apart from each other around the nuclei
What are the names of the shapes of molecules and ions with up to 6 electron pairs?
- 2 pairs - linear - 180
- 3 pairs - trigonal planar - 120
- 2 pairs, lone pair - non linear - <120
- 4 pairs - tetrahedral - 109.5
- 3 pairs, lone pair - pyramidal - 107
- 2 pairs, 2 lone pairs - non linear - 104.5
- 5 pairs - trigonal bipyramidal - 90, 120
- 6 pairs - octahedral - 90
What is electronegativity?
the measure of the tendency of an atom to attract a bonding pair of electrons, measured using the Pauling Scale
What is a polar bond?
A molecule with a difference of 0.4 electronegativity has a dipole, a molecule with an overall dipole is polar
What is a permanent dipole?
Also described as polar, it is due the electronegativity differences of atoms in a molecule
What is a polar molecule?
molecule that contains an overall polar dipole
What is a dipole?
Occur due to the unequal sharing of electron meaning one area is more negative.
How do permanent dipole-dipole interactions affect intermolecular forces?
the d+ and d- charges in polar molecules cause weak electrostatic forces of attraction between molecules, they happen in addition to induced dipoles
How do induced dipole-dipole interactions affect intermolecular forces?
Electrons are moving around the atom very quickly, and at any particular moment one side will be more negative, so it will have a temporary dipole. This causes a temporary dipole in another neighbouring atom
What is hydrogen bonding?
Strongest intermolecular force, happens when a hydrogen is covalently bonded with a nitrogen, oxygen or flourine. The bond is very polarised, so much that a weak bond is formed between a hydrogen or one molecule and a N, O or F of another
Why is the density of ice smaller than water?
in ice molecules of H2O are held in a lattice, when it melts the hydrogen bonds are broken, so water has less of them.
What does water have a relatively high melting and boiling point?
Due to the strength of the intermolecular forces in hydrogen bonds
What are simple molecular lattices?
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Effect of structure and bonding of covalent compounds on melting points?
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Effect of structure and bonding of covalent compounds on boiling points?
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Effect of structure and bonding of covalent compounds on solubility?
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Effect of structure and bonding of covalent compounds on electrical conductivity?
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