22. Electronic Arrangement

what is a spectrometer?

an instrument used to view line emission spectra

energy level

the fixed energy value that an electron in an atom may have

in what state do atoms normally exist?

ground state

ground state

one in which the electrons occupy the lowest available energy levels

what is it called when an electron uses absorbed energy to jump from lower energy levels to higher energy levels?

electron transition

excited state

one in which the electrons occupy higher energy levels than those available in the ground state

electrons in the excited state are…

unstable

what happenes when an electron falls back down to the lower level?

they release energy in the form of a photon of light

since the electron is falling back down to a fixed energy level…

only fixed amounts of light can be given off - light of a definite frequency

to calculate the frequency of the light emitted

E2 - E1 = hf

when an electron falls to n=1…

gives off UV range

when an electron falls to n=2…

gives off visible range

when an electron falls to n=3, 4, or 5…

gives off IR range

what series contains all of the lines in the visible region of the hydrogen spectrum?

balmer series

what series contains all the lines in the UV region of the hydrogen spectrum?

lyman series

what series contains all the lines in the IR region of the hydrogen spectrum?

paschen series

what element does this emission line spectrum belong to?

hydrogen

limitation of bohr's theory 1

did not take into account the presence of sublevels

limitation of bohr's theory 2

did not take into account the fact that the electron had a wave motion

limitation of bohr's theory 3

heisenberg's uncertainty principle was in conflict with bohr's theory

limitation of bohr's theory 4

bohr referred to 2D orbits, electrons are actually found in 3D orbitals

one line on emission line spectra was actually…

a number of lines very close together - sublevels

electrons have a…

'wave-particle' duality

heisenberg's uncertainty principle

it is impossible to measure both the velocity and the position of an electron at the same time - therefore we can only talk about the probablity of finding an electron

atoms in the ground state absorb…

the same radiations as they emit in the excited state

what can atomic absorption spectrometry be used for?

detecting elements present in a substance, detecting the presence of heavy metals in a water sample

how many sublevels does n=1 have?

1 sublevel (1s)

how many sublevels does n=2 have?

2 sublevels (2s, 2p)

how many sublevels does n=3 have?

3 sublevels (3s, 3p, 3d)

how many sublevels does n=4 have?

4 sublevels (4s, 4p, 4d, 4f)

to find the order in which sublevels are filled

arrows through

how many electrons can an s sublevel hold?

2 electrons

how many electrons can a p sublevel hold?

6 electrons

how many electrons can a d sublevel hold?

10 electrons

sublevel

a subdivision of an energy level containing one or more atomic orbitals, all of which have the same energy

orbital

a region of space within which there is a high probability of finding an electron

what shape is an s orbital?

spherical

what shape is a p orbital?

dumbbell shaped

how many orbitals are in an s sublevel? name them

1, s

how many orbitals are in a p sublevel? name them

3, px, py, pz

aufbau principle

when building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels

pauli exclusion principle

no more than two electrons may occupy an orbital and they must have an opposite spin

hund's rule of maximum multiplicity

when two or more orbitals of equal energy are available, electrons will fill them singly before filling in pairs

why do copper and chromium have unique electron configurations?

sublevels that are exactly half-filled or completely filled have extra stability, so copper and chromium rearrange themselves to make themselves extra stable

chromium electronic configuration

1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5

copper electronic configuration

1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10

when writing full electronic configurations of ions…

add square brackets and a charge

sigma bond

a bond formed by the head-on overlap of two atomic orbitals

all single bonds are…

sigma bonds

pi bond

a bond formed by the sideways overlap of p orbitals

every double bond contains…

1 sigma bond, 1 pi bond

every triple bond contains…

1 sigma bond, 2 pi bonds

sigma bonds are stronger than pi bonds because…

there is more overlapping of orbitals in sigma bonds

what pi-bonding system does benzene have?

2 doughnut-shaped electron clouds

how many sigma bonds does benzene have?

12, 6 C-H bonds, 6 C-C bonds