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Learn about chemical bonding and the attractive forces that hold atoms together in compounds. Breaking and forming bonds involve energy changes, making them endothermic and exothermic processes. Understand Lewis Dot Structures and how to represent valence electrons.
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Chemical Bonds These are the attractive forces that hold atoms together in a compound
Breaking a bond… Takes energy to overcome the attractive forces Therefore, breaking bonds is endothermic Energy + XY X + Y
Forming a bond… When a bond between two atoms is formed, energy is released. The bonded atoms are more stable together than they were alone. Therefore, forming bonds is exothermic X + Y XY + energy
Lewis Dot Structure (also called electron dot diagrams), show only the VALENCE e- in an atom. For bonding, only the valence e- are important. One dot = 1 e-
Lewis Dot Structures Since an atom can only have a max of 8 valence e-, we will never need more than 8 dots One dot = 1 e-
To show an atoms valence e- imagine a “box” around the atom’s symbol: Since Neon has 8 valence e-, it will have 8 dots, 2 on each “side”