Mr Hoffman’s Regents Chemistry
Chapter 5 Study Guide
NYS Core Curriculum – Physical Setting - Chemistry
Major Understanding 3.1h In the wave-mechanical model (electron cloud model) the electrons are in
orbitals, which are defined as the regions of the most probable electron location (ground state).
Major Understanding 3.1i Each electron in an atom has its own distinct amount of energy.
Major Understanding 3.1j When an electron in an atom gains a specific amount of energy, the electron is
at a higher energy state (excited state).
Major Understanding 3.1k When an electron returns from a higher energy state to a lower energy state, a
specific amount of energy is emitted. This emitted energy can be used to identify an element.
Major Understanding 3.1l The outermost electrons in an atom are called the valence electrons. In
general, the number of valence electrons affects the chemical properties of an element.
Chapter 5 Objectives
At the end of this chapter the student will be able to:
 Compare and contrast the nature of light as both a particle and a
wave. (5.1)
 Identify an element based on is emission spectrum. (5.1)
 Explain the hydrogen emission spectrum based on electron transitions
in the Bohr Model (5.2)
 Identify the type and number of orbitals in the first four principal
quantum levels. (5.2)
 Write the orbital notation, electron configuration and simplified
electron configuration for the ground state of any element up to #92.
(5.3)
 Determine the number of valence electrons for an element. (5.3)
 Draw an electron dot structure for any element up to #86 (5.3)
Vocabulary
electromagnetic radiation (EMR)
wavelength
frequency
amplitude
electromagnetic spectrum
quantum
Plank's constant
photoelectric effect
photon
emission spectrum
ground state
quantum mechanical model
atomic orbital
principle quantum number
electron configuration
orbital diagram
noble-gas notation
aufbau diagram
Pauli exclusion principle
Hund's rule
valence electron
electron-dot structure
Main Ideas
 Electromagnetic radiation (EMR) is a form of energy.
 EMR = radiation = Light (three names for the same thing)
 Visible Light is energy we can see.
 Light is a wave and a particle. Einstein used the photoelectric effect to
illustrate how this is possible.
 Atomic Emission Spectra are created by excited electrons '"falling
back" to their ground state and releasing energy as radiation.
 Every line on an emission spectrum is a result of an electron transition
which is a specific amount of energy (quantum of energy).
 The Bohr Model (1913) describes the motion of electrons in circular
orbits. The larger the orbit - higher the energy. (Only worked for
hydrogen)
 The Wave-mechanical (quantum mechanical) model (1920's) describes
electrons as waves. The current theory. Created the concept of
principal quantum numbers and orbitals (s,p,d and f)
 Electron Configurations describe the locations of electrons in atoms.
 Valence electrons are the electrons in the outermost shell of an atom.
They are what dictate chemical properties (and some physical
properties).
 Valence electrons are possibly the most important concept in
chemistry.