Electrons In Atoms

Scientific notation

• a way to express a very large or small number 

  • To convert a decimal into scientific notation, move the decimal until you have a number between 1 and 9.999

  • Place a x10 and add the exponent equal to the number of times you have moved the decimal 

    • If the exponent is positive, the decimal has moved left

    • If the exponent is negative, the decimal has moved right 

  • To put into the calculator, use the EE button to represent the x10

Standard notation

• To convert scientific notation to standard, move the decimal as many times as the exponent

  • If the exponent is positive, the decimal moves right

  • If the exponent is negative, the decimal moves left

Light

• Light is a kind of electromagnetic radiation

  • includes many types: gamma rays, x-rays, radio waves, etc

• Speed of light = 2.998 x10^8m/s → abbreviated as “c”

  • All electromagnetic radiation travels at the same rate as all light when in a vacuum (no friction) 

    • All light has different wavelengths

Equation for wavelengths 

Equation: c = λⱱ

• c = speed of light, constant, 2.998 x108m/s 

• λ (lambda) = wavelength, in meters

• ⱱ (nu) = frequency in units of hertz (hz) or sec-1

Relationship between wavelength and frequency

• Wavelengths and frequency are inversely related 

  • As one goes up the other goes down 

    • Small wavelengths = high frequency + more energy

    • Big wavelengths = low frequency + less energy

  • Different frequencies of light are different colors

  • There is a wide range of frequencies, and the whole range is called a spectrum 

Energy

• E=hⱱ

  • E = energy in joules (j) of a quantum of radiation 

  • ⱱ is the frequency of radiation emitted in units of hertz (hz) or sec-1

  • h is a fundamental physical constant known as planck’s constant 

    • h=6.626 x10-34 j*s

Atomic orbitals/sublevels

• Within each energy level, the complex math of Schrodinger's equation describes several shapes 

• These are called atomic orbitals → regions where there is a high probability of finding an electron 

• Sublevels → like theater seats, arranged in sections

  • Letters: s (2), p (6), d (10), f (14) 

Aufbau principle

• electrons enter the lowest energy level first 

• This causes difficulties because of the overlab of orbitals of different energies 

Pauli exclusion principle

at most two electrons per orbital - different spins 

Hund’s rule

when electrons occupy orbitals of equal energy, they dont pair up intil they have to 

Energy levels

• First energy level 

  • Has only 1 s orbital 

  • Only 2 electrons 

  • 1s^2

• Second energy level 

  • Has s and p orbitals 

  • 2 in s and 6 in p = 8 total electrons

  • 2s^2, 2p^6

• Third energy level 

  • Has s, p, and d orbitals 

  • 2 in s, 6 in p, and 10 in d = 18 total electrons 

  • 3s^2, 3p^6, 3d^10

• Fourth energy level 

  • Has s, p, d, and f orbitals 

  • 2 in s, 6 in p, 10 in d, and 14 in f = 32 total electrons 

  • 4s^2, 4p^6, 4d^10, 4f^14

Typical order

1s2, 2s2 2p6, 3s2, 3p6 4s2, 3d10, 4p6, 5s2, 4d10, 5p6

Exceptions to orbitals 

• 4s1, 3d5 instead of 4s2, 3d4

• This gives us 2 half filled orbitals 

• Half full is slightly lower in energy that a fully filled orbital but there is still more stability 

• Same principle applies to copper 

• Atoms like to have the lowest energy as possible 

  • Exceptions are usually when there is d4 or d9

Orbitals fill in order

• Lowest energy to higher energy 

• Adding electrons can change the energy of the orbital 

• Full orbitals are the best solution 

  • Half filled are next best 

    • Makes them more stable and changes filling order

Ground vs Exited state

• Excited state is when the orbitals do not full up fully before filling another one 

  • Does not apply to exceptions as that is its ground state 

  • Arborbs energy → less stable and often temporary 

• Ground state follows energy rules

  • Have the lowest possible energy

Metals

• Electrical conductors 

• Have luster 

• Ductile (can be made into a wire) 

• Malleable

Non-metals

• Generally brittle + non lustrous 

• Poor conductors of electricity and heat 

• Some are gasses (O, N, Cl)

• Some are brittle solids (S)

• one is a fuming dark red liquid (Br)

Metaloids

• Border the 2 sides

• Properties are intermediate between metals and non-metals

• Very useful as they have both properties 

• Ex: silicon → tech used in electronics as it can carry a current but does not heat up  

Group 1

• Group 1: alkali metals 

  • Forms a base (or alkali) when reacting with water 

    • Only have 1 outer electron → more reactive 

Group 2

• Group 2: alkaline earth metals

  • Form bases with water, do not dissolve well, hence “earth metals”

Group 17

• Group 17: halogens 

  • Salt-forming 

  • Half of diatomics (those that are more stable in 2) are halogens

Group 18

• Group 18: noble gasses 

  • Called inert gasses as they rarely take part in reactions → very stable 

  • Have an electron configuration that has the outer p and s sublevels full 

Groups 1,2,13-17

• Wide range of properties → good representation

• Some are metals, non-metals, and metaloids

  • Some are solids, while others are liquids or gasses

• Their outer s and p electron configurations are not filled 

Group 2-12

• Groups 2-12: transition metals 

  • Electron configurations have the outer s sublevel full and is not filling the d sublevel 

    • A transition between the metal areas and non-metal area 

Inner transitional metals

• Inner transitional metals → located below the main body in horizontal rows 

  • Electron configuration has outer s sublevel filled, and is now filling the f sublevel