Chapter 1

Periodic Table Basics

• atomic number = number of protons

• molar mass (grams) of element

• horizontal = periods

• vertical = groups

  • Group I = alkali metals

  • Group II = Alkaline Earth Metals

  • Group III - XII = Transition Metals

  • Group VII = Halogens

  • Group VIII = Noble Gases

• mass number = sum of neutrons and protons

• isotopes = elements (obviously same # of protons) varying neutrons

Moles

• Avogadro’s # 6.022 * 10^23 particles per mole

• M = molarity or mol/L (* remember mol is moles)

• moles = grams/molar mass

• moles = PV/RT

  • P = pressure (atm)

  • volume (L)

  • temperature K)

  • R = gas constant 0.0821 (L atm / mol K)

    • many gas occur at STP (standard temperature pressure), P = 1 atm and T = 273 K

    • can convert directly between volume of gas and number of moles

• moles = liters/ (22.4 L/mol)

Molarity

• M = moles of solute / liters of solution

Percent Composition

• To calculate you must separate the compound by elements

• Take the molar mass of each and find the mass of each element in compound

• convert by dividing each mass of substance by the TOTAL mass of ENTIRE compound and multiply by 100

Empirical & Molecular Formulas

• Finding empirical formula of compound

  • start by assuming the percentages total up to 100g (ex: 55.6% is 55.6 g or 7.11% is 7.11g)

  • Divide each gram you get by the molar mass of the pure element

  • Divide all the moles now by the lowest number of moles calculated above

  • Should receive the subscript of the elements in formula

• Find the molecular formula from empirical formula

  • Find mass each element

    • Use molar mass of element x subscript

    • Combine to find total molar mass of compound

    • divide mass given by molar mass of compound and find molecular formula

Coulomb’s Law concepts

• F(columbic) = magnitude of positive charge x magnitude of negative charge / distance btwn negative charge

Bohr’s Model

• electromagnetic radiation: electrons jump to higher energy level

Photoelectron spectroscopy

• ionization energy: amt of energy necessary for electrons to be ejected

• kinetic energy: energy of incoming radiation must be conserved & any of energy that does not go into breaking electron free from nucleus is converted in KE

  • EQUATION: incoming radiation energy = binding energy + kinetic energy (ejected electrons)

Spectra

• photoelectron spectrum (PES): amt of ionization energy for all electrons ejected from nucleus

• subshells: shape of space electron can be found

Electron Configuration

• s subshell: max 2

• p subshell: max 6

• d subshell: max 10

• f subshell: max 14

• Shorthand or normal notation (remember brackets for shorthand)

Aufbau principle: building up electron config of atom, electrons placed in orbitals, subshells, and shells in order of increasing energy

Pauli Exclusion Principle: two electrons share orbital cannot have same spin * when draw arrows make sure they are opposite

Hund’s Rule: when electron is added to subshell, always occupy empty orbital if one is available

Predicting Ionic Change:

• valence electrons in outermost s and p subshells

• ion: atom either gained or lost electrons

• cation (positive charge) anion (negative charge)

Periodic Trends

1. electrons are attracted to protons in nucleus of atom

• closer electron is to nucleus, more strongly it is attracted

• more protons in nucleus, more strongly electron is attracted

2. electrons repelled by other electrons in atom; electrons are between valence and nucleus, valence electron will be less attracted to nucleus (electron shielding)

3. completed shells are “stable”; atoms will add or subtract valence electrons to create 'complete’ shells if possible

Atomic Radius

• approximate distance form nucleus of atom to its valence electrons

• LEFT TO RIGHT OF PERODIC TABLE

  • protons are added to nucleus → valence electrons more strongly attracted → decreases atom radius

    • IF electrons added in same shell, NOT much shielding effect since abt same distance from nucleus

• TOP TO BOTTOM OF PERODIC TABLE