IB chemistry: topic 2: electron shells and orbitals

what was Bohr Theory?

the atom consisted of a small nucleus of protons and electrons surrounded by circulating electrons

what is an isotope?

forms of an element with the same number of protons but different number of neutrons - results in different physical properties

what is true of isotopes?

same chemical properties, same atomic number, different physical properties

what is a shell?

a group of atomic orbitals with the same principal quantum number (n)

what is "n"?

principal quantum number

what does the principal quantum number indicate?

the shell that the electrons occupy

what is the maximum number of electrons that can occupy a shell?

2n²

what does the principal quantum number represent?

the overall energy of each orbital, which increases the further the shell is from the nucleus

what is an orbital?

a region of space where one is likely to find an electron

what is an example of Heinsberg uncertainty principle?

orbitals

what are characteristics of orbitals?

can hold up to 2 electrons as long as they have opposite spin

what is an example of Pauli's exclusion principle?

2 electrons held in orbitals that have opposite spin

what are the four orbitals?

s, p, d, f

what shape is "s" orbital?

spherical

what shape is "p" orbital?

dumbbell

what shape is "d" orbital?

various

what shape is "f" orbital?

various

what is the occurrence of "s" orbitals?

one in every principal level

what is the occurrence of "p" orbitals?

three in levels 2 upwards

what is the occurrence of "d" orbitals?

five in levels 3 upwards

what is the occurrence of "f" orbitals?

seven in levels 4 upwards

why are orbitals not filled in numerical order?

as the principal energy levels get closer together as you get further from the nucleus, resulting in overlaps in sub levels

what is the first example of a sub level overlap?

4s orbital is filled before the 3d orbitals

what are elements that do not follow the orbital filling rule?

chromium and copper

how does chromium's orbitals fill up?

3d fills up so it is semi full, 3d⁵, leaving 4s as 4s¹

how does copper's orbitals fill up?

3d fills up to it is full, 3d¹⁰, leaving 4s as 4s¹

why do copper and chromium have unique electron configurations?

it is much more stable to fill up (semi or full) their 3d orbitals

when forming ions, how do the electrons leave the shells?

electrons are removed first from the highest occupied orbital, 4s THEN 3d