Chem 130 Chapter 4

Electromagnetic radiation

form of energy that can be described as a moving wave of magnetic and electrical potential

Amplitude

the maximum displacement of a periodic wave from zero

Frequency(v)

the number of crests that pass a given point per second

Hz

the unit of inverse second s^-1

Inverse proportionality

if one variable increases the other variable decreases and vice versus

Direct proportionality

if two quantities increase or decrease in the same ratio

Photoelectric effect

shining light of higher energy does not increase the number of electrons ejected but increases the energy that the electrons possess when they are ejected; the brightness of the light is proportional to the number of electrons emitted

Photons

tiny, individual packets of energy

Work function

the minimum energy necessary to remove an electron from the surface of the material in a vacuum

Light absorption

occurs when an atom absorbs light energy from the surroundings and gains energy

Light emission

occurs when an atom has excess energy and gives off energy by emitting light

Bohr model of atom

electrons must be found at only specific distances from the nucleus, in orbits; electrons travel in circular paths in discrete energy levels

Ground state electrons

the lowest energy level and the closest to the nucleus

Excited state electrons

higher energy levels; will emit energy to return to the more stable ground state

Ionization

process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules(ions) through gaining or losing electrons

Heisenberg uncertainty principle

the velocity of an electron is due to its wave-like nature and its position is due to its particle-like nature

Electron orbitals

a region of space surrounding the nucleus where an electron is likely to be found

Quantum numbers

arise from solving the solving the Schrodinger equation and provide a "mathematical address" for an electron; four quantum numbers

n

principle quantum number(the shell)

l

angular momentum quantum number(the sub shell)

ml

magnetic quantum number

ms

spin quantum number

Subshells

any one of the four orbitals making up an electron shell of an atom

Pauli exclusion principle

states that no two electrons in an atom can have the same set of quantum numbers, so we need to differentiate the Z electrons that can occupy the same orbital

Aufbau principle

the process of filling the sub shells from the lowest energy upward

Hund's rule

states that the electrons within a given subshell remain as unpaired as possible

Degenerate

orbitals within the same subshell that are at the same energy level

Isoelectronic

atoms and ions that have the same electron configuration

Determine a set of four quantum numbers that could describe the location of an electron
in the highest energy subshell of a strontium (Sr) atom.

Sr: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2; 5s2 is the highest energy; 5s2- n=5, l=0, ml=0, ms=1/2 or -1/2

Order the following orbitals in increasing energy: 4p, 2s, 3d, 4f , 3p

2s, 3p, 3d, 4p, 4f

What is the electron configuration of Fe?

1s2 2s2 2p6 3s2 3p6, 4s2, 3d6

Is it possible for an atom with an even number of electrons to have one or more unpaired
electrons in its orbital diagram? Why or why not? Can you provide an example to
support your answer?

Yes, O has 8 electrons and has 2 unpaired electrons; O: 1s2 2s2 2p4

What is the electron configuration of the O-2 ion? What neutral atom is it isoelectronic
with? Keeping in mind what we have learned about the charge of ions that typically
form from the halogens, what halogen ion would you expect to form that would also be
isoelectronic with O-2?

O-2 has 10 electrons; 1s2 2s2 2p6; It's isoelectronic with Ne; F- also has 10 electrons so it's isoelectronic with F-

What atom would have the electron configuration [Xe] 6s2, 4f14, 5d6 ?

Os