Bonding, Replacements, Redox Reactions Bonding, Replacements, Redox

Review - ions Atom – a particle with NO charge (protons = electrons) Ion – a particle WITH a charge (protons ≠ electrons) Cation – positive ion Anion – negative ion Protons NEVER change (atomic #) Example: If Na (Sodium) has a +1 charge, that means it lost one electron. Why: Protons are positive and electrons are negative. So sodium lost one “negative” particle, there is an imbalance. Atom (p=e) Ion (p≠e) 11 protons = 11 electrons 11 protons = 10 electrons No Charge +1 charge

Practice Did it gain or lose an electron? What is the charge? Cl -1 Gained 1 electron B -2 Gained 2 electrons Ga +3 Lost 3 electrons H Neither, no charge, its an atom Li +1 Lost 1 electron What is the charge? Beryllium: gained 1 electron -1 charge Potassium: lost 3 electrons +3 charge Lithium atom No charge! Boron: lost 2 electrons +2 charge Nitrogen: gained 3 electrons -3 charge

Ionic Bonding

Sodium lets Chlorine use its valance electron

http://www. matsceng. ohio-state http://www.matsceng.ohio-state.edu/mse205/lectures/chapter2/chap2_slide7.htm

http://www. matsceng. ohio-state http://www.matsceng.ohio-state.edu/mse205/lectures/chapter2/chap2_slide8.htm

Ionic Bonds: One big greedy thief dog Ionic Bonds: One big greedy thief dog! Ionic bonding can be best imagined as one big greedy dog stealing the other dog's bone. If the bone represents the electron that is up for grabs, then when the big dog gains an electron he becomes negatively charged and the little dog who lost the electron becomes positively charged. The two ions (that's where the name ionic comes from) are attracted very strongly to each other as a result of the opposite charges. http://library.tedankara.k12.tr/webchem/Chemical%20bonding%20and%20intermolecular%20forces/ICSD%20Bonding/Bonding%20by%20Analogy%20Dog%20-%20Bone%20Bonds.mht

Surprise!

Single & Double Replacement Reactions Single-replacement reaction: a chemical reaction in which one element is substituted for another element in a compound, making a new element and a new compound as products. 2NaCl(aq) + F2(g) → 2NaF(s) + Cl2(g) Chlorine is replaced by Fluorine Example: Formation of rust on Iron (Fe) in the car's metal body can oxidize forming iron oxide (Fe2O3), or rust.  Chemically, the iron reacts with water and oxygen to form hydrated iron oxide.  4Fe(s) + 2H2O + 3O2(g)  2Fe2O3 • H2O

Single & Double Replacement Reactions Double-replacement reaction: occurs when parts of two ionic compounds are exchanged, making two new compounds.  CuCl2(aq) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2AgCl(s) Chlorine & Nitrate switched Example: Baking a cake – baking soda (NaHCO3) mixes with acidic substances in the batter NaHCO3 + HA (acid)  NaA + H(HCO3) H(HCO3) decomposes into CO2 and Water. CO2 is responsible for making the cake rise

Redox Reactions Oxidized? Reduced? OIL  Oxidation is losing The loss of electrons The gain of oxygen The loss of hydrogen Reduced? RIG  Reduction is gaining The gain of electrons The loss of oxygen The gain of hydrogen

Reduced? Oxidized? Redox Reactions Burning of methane. CH4 + 2O2 -> CO2 + 2H2O Carbon is oxidized (loses all four hydrogen) Reduced? Cl2 + H2 → HCl Hydrogen is added to chlorine to form hydrogen chloride. Thus, chlorine gas is getting reduced to form hydrochloric acid.

http://www.bbc.co.uk/scotland/education/bitesize/higher/chemistry/energy/bsp1_rev.shtml Read the 4 slides and take the quiz at the end http://www.ewart.org.uk/science/structures/str13.htm http://www.ewart.org.uk/science/structures/str14.htm http://www.ewart.org.uk/science/structures/str7.htm http://www.wpbschoolhouse.btinternet.co.uk/page04/4_72bond/4_72bondQ.htm