Bonding and electrons Flashcards
What is an orbital?
A region around a nucleus that can hold up to two electrons with opposite spins
What order do the orbitals fill up? Are there any exceptions?
s, p, d, f
- 4s subshell fills and empties first
- In p,d,f orbitals, electrons go into separate orbitals until each orbital in that sublevel has at least one electron in it
What is ionic bonding?
The electrostatic attraction between positive and negative ions.
What is the structure of ionic compounds? (2)
- Attracts from all directions
- So giant ionic lattice
Why do ionic compounds have high melting and boiling points?
High temp. needed to provide enough energy to overcome strong electrostatic forces between ions
Are ionic compounds soluble? (2)
- Only in polar solvents (like water)
- solubility requires the lattice to break down and water molecules to attract and surround ions
Why can’t ionic compounds conduct electricity as solids but can as liquids or dissolved in water? (4)
- As solid, ions are in a fixed position in giant lattice
- there are no mobile charge carriers (when solid)
- When liquid or dissolved, ionic lattice breaks down
- ions are free to move around as mobile charge carriers
What is covalent bonding?
Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
What are pi and sigma bonds?
- Sigma bond= two s orbitals overlap
- Pi bond= sideways overlap of two p orbitals
What is the expansion of the octet? Example? (3)
- When an atom can have more than 8 electrons in its outer shell
- Only starts from n= 3 as there are d orbitals
- Examples = SF6 (6 pairs of electrons)
Definition of a dative covalent bond?
A covalent bond where the shared pair of electrons have been supplied by one of the bonding atoms only
What is meant by average bond enthalpy?
A measurement of covalent bond strength
