Drawing Atomic Models
Remember that atoms are made up of three subatomic particles:
Protons – positively charged particles that are found in the nucleus.
Neutrons - neutrally charged (meaning no charge) particles found in the nucleus.
Electrons – negatively charged subatomic particles found outside of the nucleus in
the region known as the electron cloud.
Drawing atomic models;
Remember that models are not 100% accurate, but are used rather as a tool to help us understand something that cannot be physically observed. In this case you should remember that although the models we will be drawing do not reflect it, the nucleus is incredibly small. It makes up only 1/100,000th the entire atom. Additionally you should remember that the electrons are much farther away from the nucleus than the way that you will be drawing them.
To draw an atom you must know the following:
The number of protons, which is equal to the atomic number.
The number of electron, which is equal to the number of protons (in a neutral
atom).
Electrons are spread out over energy levels. There is a maximum number
of electrons that each energy level can have.
Energy Level of Electrons Maximum Number of Electrons
1 2
2 8
3 18
4 32
Atoms become stable when they have “8” electrons in their outermost energy level with the exception of elements having only one energy level, them they are stable with only “2” electrons.
The number of neutrons, which is derived from the mass number.
To find the mass number, round the atomic mass to the nearest whole
number.
Example:
Na
Sodium
Atomic Number = 11
Atomic mass = 22.990 therefore the Mass Number = 23
Protons = 11
Electrons = 11
Neutrons = 23 – 11 = 12
Protons and neutrons are in the nucleus of the atom. There are 2 electrons in the first energy level, 8 electrons in the second energy level, and 1 electron in the third energy level.