Unit Two – Chemistry

Flashcard maker : Cindy Krause





Smallest partical of an element




  • Atoms are indivisible and indistructable
  • No experiments. Noe scientific method.




  • Developed the Atomic theory
  • Believed that a few kinds of atoms made up all matter
  • Elements are composed of only one kind of atom; and compounds made from two or more atoms




  • Studied the cthode ray tube-made of particles that were negativley charged called them electrons
  • Made the plum-pudding model – said that electrons were embeded on a postivley charged ball of matter




  • Preformed the gold foil experiment (disproved plum pudding model)
  • Said that atoms are mostly empty space




  • Electrons can olnly be certain distances away from nucleus (distance corresponds with energy level)
  • Farthest away highest energy
  • Closest, lowest energy





The difference between energy levels




  • Said Rutherford only accounted for only half the mass of the nucleus
  • Proved the presence of nuetrons in the nucleus




Proved the charge to mass ratio of an electron




  • Negative charge
  • Orbit around nucleus
  • Mass so low its neglected




  • Positivley charged
  • located in nucleus
  • mass = 1 amu




  • Neutrally charged
  • Located in nucleus
  • mass = 1 amu



Empty Space Concept

  • The space around the nucleus is empty
  • Electrons orbit in this space




  • Central portion of an atom
  • made of protons and neutrons



Atomic Number

  • The number of protons





  • elements with the same atomic number but different mass
  • Atomic mass is the isotopes averaged



Ground State

  • Electrons at the lowest energy level
  • Closest to nucleus



Excited State

  • Highest energy level
  • Unstable condition
  • have absorbed heat



Dual Nature of Light

  • Frequency and wavelength are inversley related
  • Frequency increases, wavelength decreases



Particle Nature

  • Shine light on matter it will conduct heat
  • Electrons DO move




  • Packets of energy
  • behave like particles




  • Cycles per second




  • Bright or intense amount of light



Continuous Spectra

  • Wavelengths (colors) Fade from one to another across the complete spectra



Bright Line Spectra

  • Spectrum that only contains certain wavelengths



When light strikes and electron

  • electron moves to higher energy level then goes back down
  • This creates bright line spectra




  • The amount of energy required to excite an electron to the highest energy level




Heisenburg’s Uncertainty Principle

Stated that the more precisley the momentom of a particle is known the less precisley the postion is known at a given time




A region of space around the nucleus of an atom where an electron is found



Principle Quantum Number

  • Each principle energy level consists of one or more sublevels
  • n = main energy level (1,2,3,4)




  • Can have one or more
  • S, P, D, F



Valence Electrons

  • All electrons in the outermost energy level




  • The nucleus and all non-valence electrons



Electron Configurations

  • 3D orbital is higher than 4S

1s; 2s; 2p; 3s; 3p; 3d; 4s; 3d; 4p…




  • An atom that has gained or lost an electron
  • Atom is no longer nuetral




  • negative ion
  • Atom has gained and electron




  • Postive Ion
  • Atom has lost and electron



Electron Dot Notation

  • The symbol and dots that show the type of atom and the valence electrons



Ionic Radius

  • The measure of the size of the atoms ion in a crystal lattace



Ionization Energy

  • The energy required to remove the most loosely held electron from an atom



Electron Affinity

  • The energy change that occurs when an atom gains an electron




  • A property of an element that indicates how strongly an atom attracts electrons (chemical bond)

Get instant access to
all materials

Become a Member