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Mr. Bean Discovery Science Bonding • Bond: Attraction between 2 or more atoms or ions • Two broad classifications • Ionic (attraction between cations & anions) • Covalent (electron sharing) BONDING • Covalent Bonding- a bond formed when two atoms share one or more pairs of electrons • Covalent Compounds- Compound in which electrons are shared- Non-metals only IONIC • Ionic bond- A bond that forms when oppositely charged species attract to one another • Ionic compound- Electrically neutral species combing cations and anions. IONS • Electrically charged objects that consists of an atom or group of atoms Cations and Anions • Cations-Chemical species with a positive charge • Anions-chemical species with a negative charge Polyatomic Ions • Species consisting of two or more atoms • A non-metal often combines with another non-metal to form an ion containing two or more atoms Some common Polyatomic Anions Ion name Ion formula - Hypochlorite ion ClO Hydrogen sulfate ion HS04- Sulfate ion 2SO 4 Phosphate ion PO 3- 4 Nitrate ion NO-3 SOME COMMON CATIONS ION NAME AND SYMBOL Sodium ion, Na+ 2+ Barium ion, Ba 3+ Aluminum ion, Al ION CHARGE 1+ 2+ 3+ Organic and Biochemical Compounds • Organic compound- any covalently bonded compound that contains CARBON • Carbon atoms form FOUR covalent bonds in organic compounds • Methane CH4 (Draw structure) • Carbon atoms have four valence electrons for bonding. Each of theses electrons forms a different C-H Bond Carbon • Carbon atom may also share two of its electrons with two from another atom to form an double bond. (up to three) • A carbon atom can never form more than a total of four bonds • Alkanes are hydrocarbons that have only SINGLE covalent bonds • C-H BONDS • C-C BONDS • Ethane C2H6 • Alkanes see table p264 Alkanes • Chemical formulas for alkanes follow a special pattern. • # of hydrogen atoms always twice more than the number of Carbon atoms. • Alkenes are hydrocarbons. • Alkenes are different from alkanes because they have at least one double • p266 covalent bond between carbon atoms. Alcohol (p273) • Alcohol have -OH groups • Organic compounds that are made of oxygen as well as carbon and hydrogen • Have HYDROXYL or -OH groups. • Methanol, CH3OH • Behave similarly to water molecules • Just like water molecules, neighboring alcohol molecules are attracted to one another Alcohols • Have much higher boiling points than other organic compounds of similar size • A large organic molecule made of many smaller bonded units. • DNA, wood, rubber, plastic • Small organic molecules bond to form long chains • Natural and Man-made • p275 Polymers • Elasticity of a polymer is determined by its structure • long thin chains • single fiber is made of billions of these chains • When chains are connected ,or cross linked(tennis net) the polymer becomes more elastic • rubber bands are elastic polymers Biochemical Compounds • Any organic compound that has an important role in living things • Carbohydrates-glucose and starch • Proteins are polymers of amino acids • Amino Acids- are made of carbon, hydrogen, oxygen and nitrogen