Transcript Bohr model of atom

Bohr Model of the atom
Electron Shells : the rings of elecrtons
around the nucleus
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2e in the first ring
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8e in the second ring
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8e in the third ring
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18e in the fourth ring
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All atoms follow this
pattern, but not all
have this many electrons
The Atomic Number of an element tells
you how many protons there are....
but it also tells you how many electrons
there are because there is the
same number of protons as electrons in an
element.
Ex: Silicon
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Silicon has an atomic number of 14. to draw the
bohr model for silicon add electrons in each layer
until there are 14
Now read “Bohr Model Diagrams” on pg 65
And do “Looking for patterns in Atoms” use to
following elements:
Hydrogen, Lithium, Berylium, Boron, Carbon,
Nitrogen, Sodium, Potassium, Fluorine, Chlorine
and Bromine
Valence electrons
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The electrons in the outermost shell are known as
valence electrons
Elements in the same family have the same number
of valence electrons
Elements in the same period have valence electrons
in the same shell
The period number indicates the number of shells
that have electrons
Noble gases
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The noble gases are very stable. (unreactive,
unlikely to form new substances with other atoms)
This is because they have their valence shells filled.
For two atoms to join together and make a new
substance, they must gain, lose or share electrons.
Elements that have a full valence shell don't need
more electrons, and don't want to give up or share
what they have, so they are super stable :)
The noble gases are: He, Ne, Ar, Kr, Xe and Rn)
Now read “How atoms become Ions” pg 67
Then do: pg 71 # 1 – 12, 14, 15