electrones

ElectronsElectronsElectrons

Electron Configuration Just a bunch of circles.? Not quite!

Electron ArrangementThe electrons that surround the nucleus of an atom are arranged in shells .Each shell has a maximum number of electrons that can exist in that shell.

Up to 2 electrons can exist in the first shellUp to 8 electrons can exist in the second and third shellUp to 18 electrons can exist in the fourth and fifth shell

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Basic Atom

NucleusElectronShell or Orbit

Beryllium Atom

ProtonsNeutronsElectrons

Boron Atom

ProtonsNeutronsElectrons

Carbon Atom

ProtonsNeutronsElectrons

Nitrogen Atom

ProtonsNeutronsElectrons

Oxygen Atom

ProtonsNeutronsElectrons

Fluorine Atom

ProtonsNeutronsElectrons

Neon Atom

ProtonsNeutronsElectrons

Sodium Atom

ProtonsNeutronsElectrons

Drawing electron dot diagramsWe can draw diagrams to show the arrangement of the electrons in each element. This is called an electron dot diagram Note the example below (the symbol is put in the middle and the electrons around in shells)

Electron ConfigurationsThe arrangement of the electrons in the electron shells can be written as an electron configuration.Looking at the sodium atom below, there are 2 electrons in the first shell, 8 electrons in the second shell, and 1 electron in the third shell.This can be written as:

2, 8, 1

Fact 1: Elements in the same group have the same number of electrons in the outer shell (this correspond to their group number)

HHHeLiBeBCNOFNeNaMgAlSiPSClArKCaFeNiCuZnBrKrAgIXePtAuHg

Fact 2: As you move down through the periods an extra electron shell is added.

HHHeLiBeBCNOFNeNaMgAlSiPSClArKCaFeNiCuZnBrKrAgIXePtAuHg

Fact 3: (Most important) All of the elements in the same group have similar properties.

HHeLiBeBCNOFNeNaMgAlSiPSClArKCaFeNiCuZnBrKrAgIXePtAuHg

ReviewLearn your elements, their symbols and atomic numbers.Finish Electron Arrangement sheetGlossary terms:ElectronElectron shellValence shellValence electron

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