Bohr Model of the atom

Electron Shells : the rings of elecrtons around the nucleus 2e in the first ring 8e in the second ring 8e in the third ring 18e in the fourth ring 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 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 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 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