Chem 101 Chapter 1-3

Alkali metals

Group 1

Alkaline earth metals

Group 2

Chalcogens

Group 16

Halogens

Group 17

Noble Gases

Group 18

Extensive property

“Extra” stuff matters, ex. nImass, volume

Intensive property

Independent of amount of stuff, ex. density, temperature, melting point.

Isotopes

Same number of protons, NEURON number changes, if there is charge, change number of electrons

Mass Spectrometry

Shows intensity versus m/z value. Look at greatest mass value to find the mass of the molecular-ion peak. If they ask for the mass number, make sure to see if it is a diatomic element because then you have to divide the number by 2!

1u = ? grams

1.661×10^-24

Molar Mass

• Mass in grams of one mole of a substance

• Same numerical value as the mass in u

• 6.022×10²³ u = 1.000 grams

Ultraviolet

Anything going to n=1

Visible light

Anything going to n=2

Infrared light

anything going to n=3

Principle quantum number (letter and what it describes)

• n

• Energy level (shell) on which the orbital resides

• Shell

• Integers greater than or equal to 1

What happens as the principal quantum number increases?

• Regular nodes # increases

• Energy increases

• Increase electron distance from nucleus

• s orbitals increase in diameter

• energy to remove electron decreases

Radial probability

The likelihood of finding an electron in a region (volume) of space a given distance from the nucleus

• Probability at every spot on the surface of a volume element with a given radius, at zero the radius is zero, therefore the radial probability would also be zero

Where on the graph are the radial nodes?

On the dips/bottom (so like on the middle of a U )

Where on the graph is the high probability of finding an electron?

On the peaks

Angular momentum quantum number (letter and what it describes)

• L

• Number of angular nodes

• this quantum number defines the shape of the orbital

• Subshell

• From zero to n-1

L= 0

S orbital

L = 1

P orbital

L= 2, L= 3, L=4

• 2= d orbital

• 3= f orbital

• 4 = g orbital

Magnetic quantum number (letter and what it defines)

• M_L

• Describes the three dimensional orientation of the orbital

• Values are integers ranging from -L to +L

• Orbitals orientation

When asked how many orbitals are possible:

• Calculate amount of MLs

Spin quantum number (letter and what it defines)

• M_s

• Describes the intrinsic magnetic field, how it is aligned

  • Simple terms: way in which the electron spins

• Electron spin

• +1/2 or -1/2

For a one-electron atom or ion, orbitals with the same ___ value have the same energy. This is called ____

• n value

• Degenerate

As the number of electrons ____ the repulsion between them also ___

Increase, increase

In many-electron atoms, orbitals with teh same n value are no longer ____

Degenerate: Because they feel repulsion by the different electrons, so now although they might be attracted to the nucleus the electrons around it repel it.

Pauli Exclusion Principle

No two electrons in the same atom can have identical sets of quantum numbers (max number of electrons that can exist in an orbital is 2)

Period on the periodic table are the ___

ROWS!! So think …… goes across, so it is the rows!!

Columns on the periodic table are the ____

GROUPS!! Think that you raise your hand when you want to be in a group, so it is a vertical line, IIIII

Aufbau Principle

Fill lower energy orbitals first

Hund’s Rule

Pairing elections takes energy: put one electron with the same spin in each degenerate orbital before pailring

Metals typically form ____

cations!! (+) by losing electrons (radii is in pm) picketers

• Generally electropositive

Nonmetals typically gain electrons to form anions!! So they are generally ___

Electronegative!

For transition metals, do you remove the n s first or n d electrons?

n s first!

What is Effective Nuclear Charge, Z_eff

The magnitude of the nuclear charge that is actually felt by the valence electrons

• Simpler terms: The real pull electrons feel from the nucleus

• Z_eff = Z- shielding (Z - # of core electrons)

• Will only observe Z_eff moving left to right

Z_eff as it moves across a row/period

• Increase

• electrons are held tighter

• Atom size decreases

Radius periodic trend

Increasing radius: down and left

Rank size by vertical (up and down first) and then horizontal (Z_eff)

Cations vs. original parent atoms

Cations are smaller because the electron electrons repulsions have been reduced, so the size decreases

Forming an anion (anion vs. parent atoms)

• Anions are LARGER

• Electron electron repulsion increases, so size also increases

When seeing which element is bigger:

• Look at charge first (matters more)

• Then look at radius/distance

Ionization

• The ionization energy is the amount of energy required to remove an electron from the ground state of a faces atom or ion

• FIRST ionization energy (IE_1) is the energy required to remove the first electron from a NEUTRAL atom (always positive). M(g) —> M(g)^+ + e^-

• The tighter the electrons are held, the greater the ionization energy because it will take more energy to remove an electron that wants to be with the nucleus.

Exceptions in Ionization trend

• Group 2 vs. Group 13

  • Electrons removed from p-orbital rather than s-orbital, outermost electron is in slightly higher energy orbital

• Groups 15 and 16

  • Electron removed comes from doubly occupied orbital, so repulsion from other electron in orbital helps in its removal

Ionization energy: Successive electrons

• More energy is required to remove each successive electron

• When all valence electrons have been removed, the ionization energy is much GREATER.

Electron Affinity

Electron affinity is the energy involved when a gaseous atom gains an electron to form an anion (A(g) +e^- —> A^- (g) )

• EA: positive = unfavorable

  • Metals: positive, doesn’t want e^- because it is more likely to be a cation

• EA: negative = favorable

  • Nonmetals (-) wants that e^- because it is more likely to be a anion)