Electrons and bonding notes
- Created by: GAdams
- Created on: 26-03-16 14:07
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- Electrons and bonding
- 1s2;2s2;2p6;3s2;3p6;4s2;3d10;4p6;5s2;4d10
- Atomic orbital: A region around the nucleus that can hold up to two electrons of opposite spin.
- Electrons are negatively charged and repel each other. Orbitals therefore have electrons of opposite spin.
- One electron occupies an orbital until they all contain one electron. After this, pairing begins.
- P-orbitals: ring/sphere shape around nucleus
- S-orbitals: double-balloon shape around nucleus.
- No. of electrons per shell: 2n^2 when n = no. of shells.
- Ionic bonding
- The electrostatic attraction between two negatively charged ions as the result of the transfer of electrons.
- Ionic compounds may form lattices since the electrostatic forces of attraction work in all directions.
- Ionic compounds have very high melting and boiling points since the electrostatic forces are very difficult to overcome by heating
- Salts may dissolve in polar solvents where the molecules break down the lattice and surround each ion.
- If the attraction between the charges is very strong then the compound is not very soluble.
- Salts may dissolve in polar solvents where the molecules break down the lattice and surround each ion.
- Ionic compounds have very high melting and boiling points since the electrostatic forces are very difficult to overcome by heating
- When solid, the ions are in a fixed position, so the charges are immobile, but, when dissolved, the lattice breaks down and the ions are now free to move as mobile charges.
- Covalent bonding
- The electrostatic attraction between a shared pair of electrons and two bonded nuclei.
- Some elements (i.e. S and B) can form covalent bonds to have more than 8 electrons in their outer shells.
- A dative covalent or coordinate bond is a covalent bond where a shared pair or electrons is a lone pair from only one of the bonding atoms.
- Average bond enthalpy is a measurement of covalent bond strength.
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