Vocabulary
Heterogenous mixture
Components that do not mix evenly
Who formulated early atomic theory?
Democritus
What is frequency?
waves per second (s^-1) or Hertz (Hz)
What is the Pauli Exclusion Principle?
maximum of 2 electrons per orbital
What is the electron configuration of Na+?
1s22s22p6
Exothermic reactions
release heat energy; compounds become more stable
The modern periodic table is based on whose framework?
Dmitri Mendeleev
What happens in an excited state?
electron(s) transition to a higher energy level
What is isoelectronic?
atoms or ions that have the same electron configuration
What is the electron configuration of Ca2+?
1s22s22p63s23p6
Groups
vertical columns in the periodic table
Atomic numbers define what?
the identity of an atom; describes protons in the nucleus
What is wavelength?
distance between two peaks of a wave; measured in meters (m) or nanometers (nm)
What is the electron capacity of the 3rd shell?
18
What is the electron configuration of S2-?
1s22s22p63s23p6
Significant figures
indicate the amount of uncertainty
Chemical symbols often include which numbers?
What is the equation for energy?
E = h x frequency OR E = h x c / wavelength
What is Hund's Rule?
when filling equal-energy levels, singly occupy orbitals before pairing
What is the electron configuration of Fe2+?
1s22s22p63s23p64s23d4
Ions
the result of atoms gaining or losing electrons; atom or group of atoms with a net positive or negative charge
Isotopes have different numbers of what?
neutrons
a lower energy level
What is the Aufbau Principle?
fill in orbitals starting with the lowest energy levels
What is the electron configuration of Mn2+?
1s22s22p63s23p64s23d3