chem u3 + u4

• Protons and neutrons


  Make up the nucleus
• APE MAN


  Atomic number = protons = electrons, Mass number = atomic number - neutrons
• Properties of metals


  • Good conductors
  • Lustrous
  • Corrode with water
• Reactivity of metals, including cations

  Increases going to the bottom, and going to left
• Cations


  Positive ions
• Properties of nonmetals


  • Generally gasses or brittle solids
  • Reactivity, including anions, increases from up and to the right
• Metalloids


  Solid at room temperature and they're semiconductors
• Period


  Horizontal and represents energy levels
• Group


  Vertical and are valence electrons
• Groups


  • Group 1: Alkali metals
  • Group 2: Alkaline Earth metals
  • Group 17: Halogens
  • Group 18: Noble gasses
• Alkali Metals


  • Lustrous and soft, they're the most reactive metals and are never free in nature, they are always bonded to another element
• Alkaline Earth Metals


  • Never uncombined in nature, not as soft as alkali metals, and are quite reactive
• Transition metals


  • The least reactive metals
• Halogens


  • Most reactive nonmetals, so reactive that they're never found free in nature. They react with alkali metals to form salts, halides
• Noble gasses


  • Colorless gasses and are very unreactive, usually in small amounts in the earth's atmosphere
• Isoelectronic


  Species with the same number of electrons, they have the same electron configuration and have similar chemical properties
• Aufbau principle


  Electrons fill the lowest energy orbital first
• Pauli Exclusion


  Each orbital holds 2 electrons with opposite spins because electrons repel each other, so they go in opposite directions
• Hunds Rule


  No empty bus seat rule
• Atom


  Has neutral charge
• Ion


  Has a charge
• Isotope


  Have the same number of protons but different number of neutrons, so their atomic mass is different
• An excited electron


  Jumps to a higher energy level
• Electrostatic interactions


  Electrons are attracted to the nucleus and are repelled by other electrons. As the distance between protons and electrons decreases, attractive force decreases. Not all electrons have the same nuclear attraction in an atom because the core electrons are closer to the nucleus than the valence, so they are held more strongly
• Atomic radius


  • Increases left because there are more protons (more nuclear charge), which makes stronger attractions between the valence electrons and the nucleus, decreasing the size
  • Increases down because more energy levels and it's not as tightly bound (decreases number of core electrons which increases shielding)
• Ionic size/ Ionic radius


  Size of an ion. If 2 species are isoelectronic, the one with less protons is larger
• Ionization energy


  The energy needed to remove the outermost electron. Depends on how tightly the valence electrons are to the nucleus. Usually endothermic because it requires energy to remove an electron
• 1st ionization energy

  • Energy + X (g) -> X^+(g) + e-
  • Ionization energy increases down because the size of the atom increases, which increases electron shielding and number of shells
  • Increases left to right because the size of the atom decreases, shielding isn't involved
• 2nd, 3rd, 4th ionization energies need more energy because there are less electrons
• Electronegativity


  Measure of an atoms attraction for the shared pair of electrons in a bond, increases up and to the right
• Electron affinity


  • Energy change when adding an electron, usually exothermic
  • X (g) + e- -> X^+ (g) + energy