Electrons and bonding Flashcards
How many orbitals are in each subshell?
s - 1 orbital
p - 3 orbitals
d - 5 orbitals
f - 7 orbitals
How many electrons are there in each shell?
1st shell - 2 electrons (s)
2nd shell - 8 electrons (s, p)
3rd shell - 18 electrons (s, p, d)
4th shell - 32 electrons (s, p, d, f)
What are the 3 rules of orbital filling?
- Orbitals fill in order of increasing energy.
- Each orbital can hold a maximum of two electrons and they must have opposite spins.
- Orbitals with the same energy mus be singularly occupied before they can be paired.
Why must electrons in an orbital have opposite spins?
To counteract the repulsion between the two negatively charged electrons.
What shape is the s orbital?
spherical/sphere
What shape is the p orbital?
dumbbell shaped
What are the similarities and differences between the p orbitals?
Similarities: both lobes are the same size and shape, all 3 p orbitals are of equal energy.
Differences: the orientation/direction of each of the 3 p orbitals are different as they are all at right angles to eachother.
What are the similarities and differences between the d orbitals?
Similarities: they’re all of equal energy.
Differences: they’re all uniquely shaped.
What’s the % chance of finding an electron in an orbital?
95%
In orbital filling diagrams, why is 4s filled before 3d?
Because the energy of the 4s subshell is actually slightly lower than 3d.
Why do we still put 3d before 4s when writing electron configurations?
When writing configurations, we stick to grouping shells.
Why are Se2- and Se+ ions both possible?
Se2- gains 2 electrons so 4p subshell is full so stable. Se+ loses 1 electron so 4p subshell is half full so stable (as all orbitals are singularly occupied).
How do we write shorthand notation?
[previous noble gas]remaining subshells
How would we write Kr in shorthand?
[Ar]3d10 4s2 4p6 as it’s ALWAYS the previous noble gas.
What are ionic bonds?
The electrostatic forces of attraction between oppositely charged ions that act in ALL directions and between ALL ions in a structure.
What is a lattice?
A regular repeating structure.
What are the disadvantages of the ball and stick model?
- Doesn’t show the positiive and negative ions.
- Ions may not all be the same shape and size.
- Doesn’t show the electrostatic forces of attraction acting in all directions.
What are the properties of ionic compounds?
- Regular lattice structure.
- High melting points.
- Doesn’t conduct electricity when solid.
- Dissolves in polar solvents.
Why do ionic compounds have high melting points?
Lots of energy is required to overcome the strong electrostatic forces of attraction between ions. Also, the higher the charge, the higher the required temperature.
Why don’t ionic compounds conduct electricity when solid?
The ions are in fixed positions so cannot move to carry charge and there are no other mobile charge carriers.
Why do ionic compounds dissolve in polar solvents?
The solvent molecules attract and surround the ions which breaks down the lattice.
What are the similarities and differences between ionic and covalent bonding?
Similarities: both involve electrostatic attraction, both give stability to their ions/molecules.
Differences: ionic bonding involves attraction between oppositely charged ions whereas covalent bonding involves attraction between shared electrons and nuclei, ions form lattices whereas covalent forms molecules, covalent involves sharing electrons whereas ionic involves transferring electrons.
What are covalent bonds?
The overlap of atomic orbitals each containing 1 electron to give a shared pair of negatively charged electrons which are attracted to the positively charged nuclei.
What are the characteristics of covalent bonds?
They’re localised and directional.
What is a molecule?
The smallest part of a covalent compound that can exist while retaining the chemical properties of the compound.
Which 3 elements are stable with 6 electrons?
Beryllium, Boron and Aluminium
What is the “expanding the octet” rule?
Only applicable between groups 5-7 and from period 3 downwards. These elements can be stable with up to 12 electrons as the d subshell becomes available for the expansion.
What is a dative covalent bond? (aka coordinate bond)
Both electrons in the shared pair of electrons have been supplied by 1 atom only in a covalent bond.
What are lone pairs?
Pairs of electrons which are not involved in the covalent bond.
What is average bond enthalpy?
A measurement of covalent bond strength.
The larger the bond enthalpy…
the stronger the covalent bond as it requires more energy to overcome the bond.
