LC CHEMISTRY- Arrangement of Electrons in the Atom

Continuous Spectrum

a rainbow is a common example of this type of spectrum

Emission Line Spectrum

a spectrum consisting of lines against a dark background

Spectrometer

an instrument used to carry out measurements on spectra

Crimson

the colour emitted by lithium in a flame test

Lilac

the colour emitted by potassium in a flame test

Green

the colour emitted by barium in a flame test

Red

the colour emitted by strontium in a flame test

Blue-Green

the colour(s) emitted by copper in a flame test

Yellow

the colour emitted by sodium in a flame test

Quantisation

the energy of an electron in an atom cannot have just any value but may only have certain specific values

Energy Level

the fixed energy value an electron in an atom may have

Ground State

(of an atom) is one in which the electrons occupy the lowest available energy levels

Excited State

(of an atom) is one in which the electrons occupy higher energy levels than those available in ground state

Photon

energy is emitted in this form of light, when an electron falls back to a lower energy level

Frequency of Light Emitted

E2 - E1 = hf

Planck’s Constant

is denoted by h

Frequency of Light Emitted

is denoted by f

Paschen Series

n=3

invisible - found in infrared region

Balmer Series

n=2

visible

Lyman Series

n=1

invisible - found in ultraviolet region

Absorption Spectrum

• produced when white light passes through a gaseous sample of an element

• consists of dark lines against a coloured background

Heisenberg’s Uncertainty Principle

it is impossible to measure at the same time both the velocity and the position of an electron

Limitations to Bohr’s Theory

• worked only for hydrogen

• did not take into account the wave motion of the electron

• Heisenberg’s Uncertainty Principle was in conflict with it

• did not take into account the presence of sublevels

Orbital

a region in space in which there is a high probability of finding an electron

S Orbitals

are spherical in shape

P Orbitals

are dumbbell shaped

Sublevel

a subdivision of a main energy level, and consists of one or more orbitals of the same energy