Chem- Atomic structure

Amplitude

the height of a wave from the origin to a crest, or from the origin to a trough

Atomic emission spectrum

a set of frequencies of electromagnetic waves given off by atoms of an element; consists of a series of fine lines of individual colours

electromagnetic spectrum

consists of electromagnetic radiation (EMR) which is the release and transmission of energy in the form of waves

Electron configuration

the arrangement of electrons in an atom

electronegativity

ability of an atom in a molecule to attract electrons to itself

frequency (v)

the number of waves that pass a given point per second

UNITS—→ s-1 or Hz

Ionization energy

energy required to remove an electron from an atom in its gaseous state

photon

a particle of EMR (electromagnetic radiation) with no mass that carries quantum of energy

Wavelength

the shortest distance between equivalent points on a continuous wave.

UNITS—→ m,cm,nm, etc…

Atoms are observed with what instrument?

Scanning tunneling microscope

Democritus

Greek philosopher that believed atoms were indivisible and indestructible. Got booed at by Aristotle so no one believed him

Thomson

Made the plum pudding model, indicating that electrons were randomly scattered around the atom

Rutherford

Shot alpha particles (He2+) at a gold foil, noticed that sometimes it got repelled, meaning that something positive was repelling it. Later discovered that the nucleus was at the center of the atom and that an atom was mostly empty space

Niels Bohr

Proposed circular paths (orbitals) and that each possible electron orbit has a fixed energy called energy levels

Chadwick

Discovered neutrons

Quantum theory (by Marx Planck)

1. Matter can gain or lose energy only in small, specific amounts called quanta. That is, a quantum is the minimum amount of energy that can be gained or lost by an atom.

2. According to Planck’s theory, for a given frequency (v), matter can emit or absorb energy only in whole-number multiples of hv, that is Planck’s constant: 6.63 × 10-34

3. The energy of a quantum is related to the frequency of the emitted radiation

Photoelectric effect

While a beam of light has many wavelike characteristics, it can also be thought of as a stream of tiny particles called photons

Continuous spectra

• Eye perceives it as white light

• Looks like a rainbow when observed through a spectroscope

• A spectrum of no lines and no bands

Bright light/ emission spectra

• A unique line spectrum emitted by each element based on the different number of electrons they each possess.

• Brightness and width of bands indicates how many photons of that wavelength are given off

• Movement of excited electrons

Atomic emission spectra

• spectral lines are produced by an atom in the excited state.

  1. Absorption of energy (electricity)

  2. Electrons are raised to a higher energy level (orbital)

  3. Electrons lose energy as they come back to lower level and that energy is given off as a photon (light wavelength)

Heinsenberg Uncertainty Principle

• At any one time it is impossible to calculate both the momentum and the location of an electron in an atom. It is possible to calculate the probability of finding an electron in a given space.

Number of electrons in each sublevel

s= 2, p=3, d=5, f=7
therefore, s= 2, pX2=6, dX2=10, fX7=14

Aufbua Principle

• Each electron occupies the lowest energy orbital available

1. All orbitals in the same sublevel have the same energy

2. The energy levels within a principal energy level have different energies (EX: 2p has more energy than 2s)

3. Orbitals related to energy sublevels within one principal energy level can overlap orbitals related to energy sublevels within another principal level (EX: 4se- have less energy than 3de-)

Pauli exclusion

• A maximum of 2 electrons may occupy a single atomic orbital, but only if the electrons have opposite spin (are in opposite directions)

Hund’s rule

Single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals.