Electrons and Electron Arrangement.

General info on electrons E- have a negative charge A neutral atom: electrons = protons. The mass of an electron is extremely small. Approximately 2000 electrons = the mass of one proton. The electron cloud determines the size, the nucleus determines the mass of the atom. Electrons spin around the nucleus in pairs in orbitals.

General info on electrons continued The definition of an orbital: A 3 dimensional space with a high probability of finding a pair of electrons. Electrons spin in pairs going the opposite direction in an orbital.

Electron arrangements (configurations) The electrons of any atom are very well organized. The first level of organization is the energy levels. Every atom’s electron cloud consists of 7 energy levels or shells. Each energy level (e.l.) has a specific energy requirement. the first e.l. has the least energy, 7 the most the energy. Not all 7 e.l. have e-. Row on per. Table = # of e.l. with e- in them.

Energy levels Each energy level has a maximum amount of electrons that it will contain. Level one: holds 2 electrons Level two: 8 electrons Level 3: 18 electrons Level 4: 32 electrons Levels 5-7: 32 electrons

Orbitals within energy levels With in each e.l. there is further organization. There are specific orbitals.( remember an orbital contains a pair of electrons.) The e.l.s and their orbitals with electrons are arranged as follows:

E.L. Orbitals total electrons 1 s = 2 e- 2 2 s=2 e-, p=6 e- 8 3 s=2 e-, p=6e-, d=10e- 18 4 s=2e-, p=6e-, d=10e-, f=14e- 32

Electron distribution around an atom

Shapes of the orbitals

Orbital shapes cont.

Shapes of orbitals

Orbitals around the nucleus of an atom

Orbitals on the table

Examples of energy levels with electrons for some elements

Diagram of the energy levels for an element

Continuous Spectrum

Electrons produce light Electrons are capable of producing light when energy is supplied. The electrons receive energy and are able to leave their ground state energy level and move to higher energy levels. At the higher energy level, the electrons are unstable and so return to their original ground state releasing the energy absorbed in the form of light.

Electrons produce light continued. This energy emitted corresponds to a particular wavelength and shows up as a line in the spectrum. When electrons return to the first level (n=1) the series of lines occurs in the ultraviolet region as this involves the largest energy change. When electrons drop to other levels different waves lengths of light are produced in the visible light range.

Emission spectrum of hydrogen

Hydrogen spectrum

Emission lines

Each spectrum is unique for each element Since every element has a unique valence electron arrangement, every element has a unique spectrum. The energy released when an electron drops from one energy level to another is unique to each element, thus, giving a unique spectrum. The spectrum for a given element can be used to identify the element such as a fingerprint can identify a human.

Emission Spectra of some elements

Continuous, absorption,emission