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Biological Organization Biological Organization “Biological Organization” How living things are organized Early Greek Theories of Matter • The theory of the 4 Elements (credited to Empedocles -- 490-435 B.C.) • According to the Greek theory of matter everything in the universe is made of four basic elements: • Fire • Air • Water • Earth Empedocles – Theory of 4 Elements Democritus 460 B.C. – 370 B.C. Democritus was a Greek Scientist and created the 1st atomic theory He hypothesized that all matter is composed of tiny units, called atoma. Considered to be the “father of modern science” Atoms “Atom” in Greek means that which can’t be cut or divided Atoms are the smallest building blocks of all life Atoms Atoms are made of smaller units called subatomic particles The three subatomic particles are: Protons (nucleus) + Neutrons (nucleus) 0 Electrons (electron cloud) - HELIUM ATOM Parts of an atom Shell proton + electron N N + - neutron HISTORY OF THE ATOM John Dalton: 1766 - 1844 Revised the atomic theory to suggest that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them ATOMS HISTORY OF THE ATOM Niels Bohr 1885-1962 1913 Bohr further refined the atomic theory by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons. Elements Many atoms of the same kind form elements Periodic Table Although there were precursors, the current periodic table is credited to Russian chemist Dmitri Mendeleev in 1869. Periodic Table Podcast http://www.youtube.com/watch?v=fLSfgNx oVGk Atomic Number The periodic table is arranged by atomic number Atomic Number is the number of protons in the nucleus (same as # of e-) How can the number of protons be determined • Atomic Number How can the number of neutrons be found? ATOMIC MASS The periodic table is also… • Organized according to states of matter ATOMIC STRUCTURE Electrons are arranged in Energy Levels or or Shells around the nucleus of an atom. • first shell a maximum of 2 electrons • second shell a maximum of 8 e- • third shell a maximum of 18 e- Molecules 2 or more atoms bonded together Ex. 2 atoms of oxygen make one oxygen molecule Compounds A molecule that contains at least 2 different elements Ex. 2 hydrogen atoms and one oxygen atom create one molecule of H20 (water) How do atoms get “stuck” together? Bonds! To get a stable outer shell of electrons, atoms either give away, take on, or share electrons. 3 Types of Bonds Ionic Covalent Metallic Ionic Bonds Formed between the transfer of electrons Produce charged ions all states. Conductors and have high melting point. Examples; NaCl, CaCl2, K2O Ions an atom or molecule with a net (overall) electric charge due to the loss or gain of one or more electrons Covalent Bonds Formed by the sharing of electrons Examples; O2, CO2, C2H6, H2O Metallic Bonds Bond found in metals, very strong Good conductors at all states, lustrous, very high melting points Examples; Na, Fe, Al, Au, Co ATOMIC STRUCTURE The structure and bonds of atoms, molecules and compounds can be represented by electron dot diagrams & Lewis Structures Valence Electrons: The outermost electrons in orbit that participate in the chemical bonds Electron dot diagram show valence electrons of one element Make an electron dot diagram for: -oxygen -hydrogen Lewis Structures show bonding of molecules Ex. Water Subscripts in a chemical formula tell us the number of atoms of each element represented Ex. H₂O How many atoms of Hydrogen? Oxygen? Draw a Lewis Structure to represent one molecule of water. Lise Meitner Lise Meitner, (1878 -1968) was an Austrian, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission (splitting an atom), an achievement for which her colleague Otto Hahn was awarded the Nobel Prize. Meitner is often mentioned as one of the most glaring examples of women's scientific achievement overlooked by the Nobel committee. 1906 1946 Marie Curie Marie Curie (1867 - 1934) was a chemist, famous for her pioneering research on radioactivity. She was the first woman to win a Nobel Prize Antoine Lavoisier (1743 – 1794) In 1778, Antoine Lavoisier, a French scientist, conducted many experiments air and theorized that the gas made some substances acidic. He named this gas oxygen, from the Greek words that loosely translate as "acid maker". While Lavoisier’s theory about oxygen and acids proved incorrect, his name stuck. Lavoisier knew that acids react with some metals to release another strange and highly flammable gas called phlogiston. Lavoisier mixed the two gases, phlogiston and the newly renamed oxygen, in a closed glass container and inserted a match. He saw that phlogiston immediately burned in the presence of oxygen and afterwards he observed droplets of water on the glass container. After careful testing, Lavoisier realized that the water was formed by the reaction of phlogiston and oxygen, and so he renamed phlogiston hydrogen, from the Greek words for "water maker". From these observations, Lavoisier established the Law of Conservation of Mass. Law of Conservation of Mass Mass is not lost or gained during a chemical reaction. http://www.britannica.com/EBchecked/topicvideo/108987/83548/Antoine-Lavoisier-discovered-the-chemicalexplanation-for-fire Chemical Equations Represents chemical changes A chemical equation is a symbolic representation of a chemical reaction. Equation Example: The burning of methane gas in oxygen is: CH4 + 2 O2 → CO2 + 2 H2O C=1 H=4 O=4 C=1 H=4 O=4 This is a balanced equation Reading Chemical Equations The two sides of the equation are separated by an arrow. – The combination of chemicals before the reaction are on the left side of the arrow – The right side indicates the combination of chemicals after the reaction. Subscript Shows the number of atoms of each element in a molecule Subscript H2SO4 – Elements Hydrogen; 2 atoms Sulfur: 1 atom Oxygen: 4 atoms – 7 atoms total Coefficients Represents # of molecules 2H2SO4 – 2 molecules of Sulfuric Acid – A coefficient is distributed to ALL elements in a compound 2 – H2 (for a total of 4 H atoms) 2 – S (for a total of 2 S atoms) 2 – O4 (for a total of 8 O atoms) Coefficient CH4 + 2 O2 → CO2 + 2 H2O For Example: Na + O2 → Na2O In this reaction, sodium (Na) and oxygen (O2) react to make a single molecule, Na2O You can change a coefficient….. You can’t change a subscript Balancing Equations The Law of Conservation of Mass states that in a chemical reaction, the quantity or amount of each element does not change. This means that each side of the equation must represent the same quantity of each element; in other words have the same number of each kind of atom. Balancing Equations Na + O2 → Na2O In order for this equation to be balanced, there must be equal amount of Na on the left hand side and on the right hand side. Right now, there is 1 Na atom on the left but 2 Na atoms on the right. We solve this problem by putting a 2 in front of the Na on the left hand side, Like this: 2Na + O2 → Na2O Balancing Equations 2Na + O2 → Na2O There are 2 Na's on the left and 2 Na's on the right. But what about the O? We now must check to see if the O's are balanced on both sides of the equation. On the left hand side there are 2 O's and the right hand side only has one. This is still an unbalanced equation. To fix this we must put a 2 in front of the Na2O on the right hand side. Now our equation reads: 2Na + O2 → 2Na2O Balancing Equations 2Na + O2 → 2Na2O Notice that the 2 on the right hand side is "distributed" to both the Na2 and the O. Currently the left hand side of the equation has 2 Na's and 2O's. The right hand side has 4 Na's total and 2 O's. Again, this is a problem, there must be an equal amount of each chemical on both sides. To fix this let's add 2 more Na's on the left side. The equation will now look like this: 4Na + O2 → 2Na2O Balancing Equations Tutorial http://www.youtube.com/watch?v=UG f60kq_ZDI