basic chemistry

basic chemistry - Basic Chemistry Why do we study chemistry...

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Unformatted text preview: Basic Chemistry Why do we study chemistry in biology? Matter Everything on Earth is made of matter Solid, liquid, gas 3 characteristics of matter: 1. 2. 3. made of elements - oxygen, hydrogen a mass or weight Occupies space Elements 92 naturally occurring elements 25 elements - necessary for life represented by symbols Na = natrium Au - aurum Periodic Table of Elements 25 elements necessary for life Carbon Oxygen Hydrogen Nitrogen Calcium Phosphorus Potassium Iron Zinc Manganese sodium Basic unit of an element have subatomic particles Atom protons, neutrons, electrons # of protons = atomic number # of protons & neutrons = atomic mass Isotopes Elements w/ different # of neutrons Many are radioactive gives off particles as atom decays scientific & medical usages Structure of an Atom 1. Central nucleus proton + charged neutron neutral in charge nucleus is positively charged Structure of an Atom 1. Outside of the nucleus are: Electrons (e) negativelycharged particles found in orbitals Each orbital has 2 e Chemical Bonding Atoms bond to form molecules Bonding involves the interaction of e How many e is in each orbital? Chemical bonding e are either taken or given away e are either shared Ionic Bonding e- are taken from or given away from one atom to another Ionic Bonding, cont'd Sodium Na Chlorine Cl have 1 e- in its outer orbital Na gives an e- to Cl forming sodium chloride Ions are formed Na+ Cl- Covalent Bonding e- are shared bet atoms Nonpolar covalent bond e- are shared equally between atoms -diatomic hydrogen Polar covalent bonds e- are shared unequally bet atoms due to different # of protons & electrons bet different atoms One water molecule 2 hydrogen atoms has e- each 1 oxygen atom has 8 e- & needs 10 to be `filled' H2O molecule - slightly neg at one end & slightly positive at other end Hydrogen bonding covalently bonded molecule bonded to hydrogen water molecule can bond with another water molecule Chemical Reactions Changes in matter through forming & breaking chemical bonds Starting materials = reactants Ending materials = products Sulfuric acid & sugar Characteristics of water Due to Hbonding Universal solvent many substances dissolve in water Shows cohesiveness faucet dripping Adhesiveness straw Large heat capacity water can absorb lots of heat before changing temperature High heat of vaporization req a lot of heat to change from liquid to a gas Freezing water is lighter as a solid rather than a liquid Some cpds break into charged particles as a liquid Ex: water breaks into H+ & OH H+ = hydrogen ion OH- = hydroxyl ion Ions Acids & Bases -Acid soln w/ lots of H+ & little OH-Base/alkaline soln w/ little H+ & lots of OH- pH pH measures amount of H+ in a soln pH scale values from 0 14 Acids 06 Bases/alkaline solns 8 14 Neutral Solutions Neutral solns pH of around 7 equal amts of H+ & OH Not corrosive ...
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