Atomic Structure and Theory

Electromagnetic Spectrum

range of all types of electromagnetic radiation, organization by frequency, wavelength or energy

electromagentic spectrum

Important equations to know about electromagnetic spectrum

• c- speed of light in a vaccum

• v - frequency (Hz)

• E - Energy (J)

• λ - wavelength (nm = 10^-9 m)

Subatomic particles found in atom

• proton (+)

• neutron

• electron (-)

Who theorized quantun theory

Max Planck

Quantum theory (Max Planck)

• Energy is quantized (discontinuous)

• Photon is a discrete packet (quantum of energy

• E= hv

• helped discover Photoelectric Effect

• E - Energy (J)

• h - Plank’s constant (6.626 X 10^-34 Js)

• v - Frequency

Photoelectric effect

• when light of a specific wavelengt, hits a material (ex. metal plate) causing it to emit electrons

• energy is quantized

Who discovered photoelectri effect

• Heinrich Rudolf Hertz - 1887

• Albert Einstein (1905) - Nobel Prize (1921)

When will a photon be ejected (photoelectric effect)

• E_photon > E_threshold

• E_threshold - (Φ) Energy threshold that must be reached for a photon to be ejected

number of e ejected from on photon (threshold reached)

1

What happens if E_photon > Φ

excess evergy goes toward the kinetic energy

Equtions for E_photon

• KE_electon- Kinetic energy of electron

• u - velocity of ejected photoelectron

• m - mass of ejected photoelectron (9.109 × 10^-31kg)

Energy transmission in hydrogen

Emission

• higher orbital lever → lower orbital level

• exicted state → lower state

• light emited after passig through a material

• M* -> M + hv 

Absorption

• lower orbital lever → higher orbital level

• lower state → excited state

• light absorbed when passig through a material

• M + hv → M*

Equation for energy at a specifc energy level

n - energy lever

R_H = 2.179 × 10^-18J

Equations for a change in energy

• R_H = 2.179 × 10^-18J

Energy of poton equation

• always positive

Suns Emission Spectrum

• large spectrum of light

• mostly UV and infrared light

Types of UV rays emmited by the sun

• UVA

• UVB

• UVC

Which UV Rays reach earth

• UVA

• UVB

UV radiation and inteaction with atomsphere

• mostly absorbed in atosphere

  • some reach earth (UVA and UVB)

body’s response to UV Radiation

produce melanin (dark pigment) to filter UVA Radiation

Chrinic exposure to UV rays can lead to…

• skin cancer

• cataracts

• genetic mutations

Electronic transitions in a molecule

absorption of light

physical sunscreens

remain on skin surface and reflect UV rays

Chemical Sunscreen

molecules that absorb UV Radiation before radiation reaches dermis (the skin)

Semiconductors

electrons must be excited from low E valence bond → higher energy conduction band

What is wave particle duality in simple terms

• waves display particle-like properties

• particles display wave like properties

Who discovered wave particle duality

• J.J. Thomson

• George Thomson

Principal quantum number (n)

• orbital energy + distance from the nucleus

• larger → further from nucleus + higher E

• n = 1,2,3…

Orbitqal angular momentum quantum number (l)

• orbital shape

• l = 0,1,2…(n-1)

• 0 = s, 1 = p, 2= d, 3 = f

• # l values = # subshells within a shell

magnetic quantum number

• orbital orientation

• m_l = -l …0…l

• # ml values = 2l+1