Chemistry Unit 3

Transverse Wave

  • Amplitude- the height of the wave; measured from highest to the center point
  • Wavelength- length of the wave; distance between two consecutive points on the wave
  • Frequency- number of waves that pass a given point every second
  • Speed- how fast the wave is moving

Electromagnetic radiation- a type of energy or wave that actually consists of two waves at 90-degree angles

Electromagnetic Spectrum- the entire range of all the different types of electromagnetic waves arranged from lowest to highest energy

Scientific Notation

  • negative exponent= a small number
  • positive exponent= large number

has to be one digit, between 1 and 9

Calculating frequency and wavelength

“c = 𝞴*𝞶”

c = speed of light = 3.0 x 108 m/s

𝞴 = wavelength (m or nm)

𝞶 = frequency (waves/sec or Hz)

1 nm  =  10-9 m

Conversion Example:

570 nm  x  10^-9__m__ = 5.7x10-^7 m \n 1 nm

Calculating the energy of one photon

E = h𝝼

The energy of a wave is directly proportional to the frequency (𝞶) of the wave.

h = Planck’s Constant = 6.626 x 10-34 J⋅s

𝞶 = frequency (waves/sec or Hz)

Atomic Emissions

  • When electrons transition away from the nucleus, they absorb energy
  • When electrons transition to the nucleus, they release energy
  • more energy= farther away from the nucleus
  • When electrons transition closer to the nucleus, they emit energy, producing colored light
  • the unique patterns of emitted energy from atoms allow us to identify them

Electron Configurations

-- maximum number of electrons in a shell is given by the formula of 2n^2, where n represents the shell number

Orbitals- subdivisions of the main shells, a three-dimensional region that contains a maximum of two electrons; not real physical barriers, they are just mathematical predictions of where the electrons are likely 90% of the time

-- All orbitals can only hold 2 electrons

-- most orbitals exist in a variety of different shapes/orientations

Kinds of orbitals:

S- subshell has one “s” orbital, spherical, located on all four shells

P- subshell has three “p” orbitals, dumbell shaped, located on n=2, n=3 and n=4

D- subshell has five “d” orbitals, double dumbell, located on n=3, and n=4

F- subshell has seven “f” orbitals, located on n=4+

Periodic Trends

Periods- rows on the table

Groups- columns on the table

Atom Size-

  • Atoms get smaller as you go up and to the right
  • metal ions will be smaller than the atom as they lose electrons

nonmetals ions will be bigger than the atom as they gain electrons

Chemical Reactivity

  • bigger atoms =more chemical reactivity

Ionization energry

ionization energy- the energy required to remove a valence electron

The smaller the atom, the more ionization energy required

Ionization energy increases when you move up and to the right

Electronegativity- the attraction an atom has for shared electrons in a bond

Increases as you move up and to the right

doesn’t include noble gases