5197459
Description
Flashcards by Bee Brittain, updated more than 1 year ago
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Created by Bee Brittain
over 8 years ago
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| Question | Answer |
| Define ' Electronegativity ' | The ability of an atom to attract the bonding electrons in a covalent bond |
| How is electronegativity measured? | Electronegativity is measured on the Pauling Scale. Across the period table, nuclear charge increases and the atomic radius decreases. A large Pauling value = atoms of the element are very electronegative. |
| The bonded pair of electrons in a covalent bond are shared equally unless... | ...1) the nuclear charges are different ... 2) the atoms may be different sizes ... 3) the shared pair of electrons may be closer to one nucleus than the other |
| Electronegativity determining ionic or covalent | If the electronegativity different is large, one bonded atom will have a much greater attraction for the shared pair than the other bonded atom. The more electronegative atom will have gained control of the electrons and the bond will now be ionic. |
| Non-Polar Bonds | - Bonded electron pair shared equally - Bonded atoms will be the same or the bonded atom swill have the same/similar electronegativity -Pure Covalent Bond |
| Polar Bonds | - Electron pair shared unevenly - Bond will be polar when the bonded atoms are different or have a large different in electronegativity - Polar Covalent Bond |
| Example: H-Cl bond | 1) A H-Cl bond is polar as the Cl atom is more electronegative than the H atom. 2) Due to it being polar, the H has a slightly positive charge and the Cl has a slightly negative charge 3) This separation of charges is called a dipole 4) This dipole doesnt change and is therefore a permanent dipole |
| Explain whether a H2O molecule is polar | The two O-H bonds have a permanent dipole as O is more electronegative than H and therefore has a slightly negative charge. Even though the two dipoles act in opposite directions, they don't exactly oppose each other. This means the hydrogen end of the molecule is also slightly positive whilst the Oxygen end of the molecule is slightly negative. |
| Explain whether a CO2 molecule is polar | A CO2 molecule isn't polar as even though the two C=O bonds have a permanent dipole, they act in opposite directions and directly oppose each other. This means the dipoles cancel out and the overall dipole is 0. You can tell they cancel as the molecule is SYMMETRICAL. |
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