- isotope - atoms of the same element that have a different number of neutrons; as a result, they have different atomic mass
- example:
- mass number (A) = number of protons (Z) + number of neutrons
- A = 35; Z = 17; chlorine (Cl)
- number of protons/electrons: 17
- A - 17 = number of neutrons (18)
- with isotopes, you put the atomic number on the bottom instead of it being on the top (ex: K & 19), and put the mass number on top
- example:
- regarding electrons and models:
- electrons do not move freely in space; confined to a certain region (principle energy levels/shells) that are numbered and give it a particular energy
- electrons in lower shells are closest to the nucleus; electrons in higher shells have more energy, have a larger volume, and therefore can hold more electrons
- shell electron counts (maximum):
- 1 = 2
- 2 = 8
- 3 = 18
- 4 = 32
- shells are divided into subshells, which consist of orbitals (regions of space where probability of finding an electron is high)
- each orbital can only have two electrons, the number just changes the amount of orbitals there are
- subshell orbital counts (maximum):
- s = 1
- p = 3
- d = 5
- f = 7
- rules to determine the ground state electronic configuration of an atom:
- electrons are placed on the lowest energy orbital beginning with 1s; then filled in order of increasing energy
- you fill in the lower subshells before you go into the higher ones (fill s and p before d and f, you know)
- orbital diagrams use boxes (orbitals) and arrows (paired/unpaired electrons) to represent electrons; two electrons in an orbital have paired spins (spins are in opposite directions), so up & down arrows are used
sep 19 2013 ∞
feb 10 2015 +
feb 10 2015 +