Let´s RECAP An element’s reactivity is determined by the number of valence electrons found in an atom of the element. In the periodic table, the number of valence electrons in each element increases from left to right across each period. Atoms tend to be stable and nonreactive if they have eight valence electrons. The force of attraction that holds two atoms together is called a chemical bond. 1" an /of /found /atom/ of /valence /reactivity /the /number/ is /the/ determined /by / element. / An /electrons /in /element’s __________________________________________________________ 2. " from / of /each /in /the /electrons /the/ right/ element /increases /table, /periodic /number /period. /across /to /left /each/ valence /In " __________________________________________________________ 3. " eight /valence /they /to /be /Atoms /stable /and /if /have /tend/ electrons./nonreactive " __________________________________________________________ 4. " of /together /called /attraction /bond. /atoms /two /chemical / that /holds /is /The /a /force “ __________________________________________________________ What are Ions? Li NEUTRAL ATOM # Protons___ # electrons ___ Atomic Number = _____ p+ e- + _ + _ _ Li + Atom with an extra POSITIVE charge What are Ions? F p+ e- + _ + NEUTRAL ATOM # Protons___ # electrons ___ Atomic Number = _____ _ _ _ F - Atom with an extra NEGATIVE charge Li + Cation Atom with an extra POSITIVE charge Anion F Element´s name Lithium Electron dot diagram (Lewis structure) Type of element (metal or non metal) Does it gain or lose electrons? P.128 Aritmethic to determine the charge Overall charge v.e = charge = 3 3+ (# v.e) – 8 = (-3) 3- Sodium Beryllium Magnesium Aluminum Nitrogen Phosphorous Oxygen Sulfur Chlorine Bromine