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Introduction to Chemical Bonding

Introduction to Chemical Bonding. Chemical Reactions:. During chemical reactions, elements combine , rearrange , or break apart with others to form new substances . New substances are created when chemical bonds are broken or created. New Substance. Original Substance. Magnesium Oxide.

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Introduction to Chemical Bonding

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  1. Introduction to Chemical Bonding

  2. Chemical Reactions: • During chemical reactions, elements combine, rearrange, or break apart with others to form new substances. • New substances are created when chemical bonds are broken or created. New Substance Original Substance Magnesium Oxide Chemical Reaction http://jchemed.chem.wisc.edu/JCESOFT/CCA/CCA3/STILLS/MAGAIR/MAGAIR/64JPG48/6.JPG http://www.bcscience.com/images/magnesium_burn.jpg Magnesium Metal http://www.polmag.pl/en/media/magnesium.jpg

  3. Evidence of Chemical Reactions: • Fire/Burning • Color change without dye • New gas created • Heat released • Heat absorbed http://amazingrust.com/Experiments/background_knowledge/Images/Fire-big.jpg http://z.about.com/d/chemistry/1/G/5/a/demonstration.jpg http://static.howstuffworks.com/gif/cold-pack.jpg http://en.wikipedia.org/wiki/Self-heating_can http://www.uncp.edu/home/mcclurem/ptable/ca_2.jpg

  4. Compounds are more than one kind of element joined together. Octet Rule: Describes how chemical bonds happen. • Atoms want a full valence (or outer electron energy level). • Full valence will mean having 8 valence electrons. http://www.chemprofessor.com/periodicqm_files/image005.gif

  5. Why are these atoms negative? Gaining electrons (and electrons are negative) means more negative charge than positive charges (protons). Octet Rule … It is easier for the atom to gain 1, 2 or 3 electrons rather than losing 5, 6 or 7. • To reach full valence, some atoms “want” to lose electrons and others “want” to gain electrons. • Atoms with FEWER than 4 valence electrons will bond by losing those electrons. • These atoms will become positively charged! • Atoms with MORE than 4 valence electrons will bond by gaining electrons (up to eight). • These atoms will become negatively charged! • Atoms with 4 valence electrons can gain or lose electrons. It depends on the element to which it is bonding. It is easier for the atom to lose 1, 2 or 3 electrons rather than gaining 5, 6 or 7. Why are these atoms positive? Losing electrons (and electrons are negative) means more protons (positive charge) than negative charges.

  6. A chemical bond is created by the sharing or exchange of electrons between elements. Example: Sodium (Na) • Valence? 1 • Easiest way to follow Octet Rule? Lose 1 electron • If following Octet Rule, what’s the charge? +1 http://www.historyforkids.org/scienceforkids/chemistry/atoms/pictures/sodium.jpg

  7. Example: Fluorine (F) • Valence? 7 • Easiest way to follow Octet Rule? Gain 1 electron • If following the Octet Rule, what’s the charge? –1 http://www.bbc.co.uk/schools/gcsebitesize/science/images/diag_fluorine.gif

  8. What will happen if Sodium and Fluorine atoms are mixed? • Electrons could transfer between the atoms. • A sodium atom could lose an electron to a fluorine atom. • Both atoms are left with full valence & are bonded together, creating a compound.

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