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If analyzed at the level of atoms, human beings are mostly composed of oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus. Source: mader and Windelspecht. Essentials of Biology. Ed. 3. 2012. McGraw-Hill. To see a larger image -- right click with your mouse to open image in new window.  - - - Elements and Atoms (Khan Academy You Tube) - - -Elements and Atoms. khanacademy. Source: https://www.youtube.com/watch?v=ZI3OlYXFQHI  To understand biology and life one must have at least some knowledge of basic chemistry. At one time, it was thought that living organisms contained a vital force (a -- not physical or chemical, perhaps religious (?) force -- once thought to cause the evolution and development of organisms, and this force accounted for their "vitality"... (see document in British Medical Journal, May 8, 1858.) Such a hypothesis has never been supported, and instead today we know that living things are composed of the same elements as inanimate objects. They differ as to which elements are most common. This chapter reviews inorganic chemistry, which largely pertains to nonliving things. It also explores the composition and chemistry of water, an inorganic substance that is intimately connected and important to the life of organisms on Earth. Chemical Elements --- Elements. (For a bigger picture click the link in the table below. Source: Used for educational purposes. From S. S. Mader. 2010. Biology. McGraw-Hill. Biology, the textbook used by the instructor since 1996. Permission given in 2001 by McGraw-Hills then sales representative, Don Grainger, to use the picture online on lecture notes.) Notice in the small table below, that in the older picture of the parrots -- to the left -- the elements are listed in PERCENT of atoms. In the later edition (ed. 10 -- to the right, same as above) the elements are listed by WEIGHT. The first picture "thumbnail" in the table is of the same figure as higher up on this page.
 Matter Everything, both living and nonliving things, is made of Matter is anything that takes up space and has mass ("weight").
def. Matter: Anything that has weight (mass) and takes up space (volume).[‰ a substance you potentially can touch] • Matter is made of basic substances called elements, which are substances that cannot be broken down to simpler substances with different properties..  -- There are 92 naturally occurring chemical elements.-- About 25 of the natural occurring elements are essential to life. Matter Elements Chemical element Elements (chemical elements) consist of atoms, the smallest part of an element that displays the properties of the element. An element and its atom share the same name. On or two letters create the atomic symbol, which stands for its name. For example, H means hydrogen, and Na (for natrium in Latin) is used for a sodium atom. You don't have to know all the elements in this class as if it was a chemistry class, some knowledge is useful. All elements and its symbols are listed in the periodic table.  There are at present 118 recognized (confirmed) chemical elements. Element 118 is Ununoctium Uuo. Periodic Table The elements can be organized into different groups in a table, called a periodic table, according to a number called the atomic number. Each element is composed of a specified number of particles called subatomic particles -- protons, neutrons, and electrons, and the elements are numbered according to the number of protons (the atomic number). The figure below is of an abbreviated periodic table. The YouTube video above, with the famous "Elements Song" (by Tom Lehrer), or the one below with "Harry Potter", is perhaps more fun and cute, but by watching it you will hopefully get an appreciation of what is out there in the real world. (To learn more click on the link to the periodic table web site above.)
Source: https://www.youtube.com/watch?v=DYW50F42ss8 Rather hear Harry Potter sing the Elements Song? Click here. Atomic Number
 Periodic table (abbreviated version). Source: Mader and Windelspecht. Essentials of Biology.  Periodic table (abbreviated version). Source: Mader. Biology. There are 92 elements found in nature in either a solid, liquid, or gaseous form. Many of the elements that are not found in nature (made artificially in a laboratory or an industrial process) are extremely unstable and decompose within seconds (or microseconds). Four (4) elements account for 96% of chemicals in the human body, and eleven (11) elements accounts for 99.9%. • Elements in the human body If analyzed at the level of atoms, human beings are mostly composed of oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus. Source: Mader and Windelspecht. Essentials of Biology. Ed. 3. 2012. McGraw-Hill. i. The 4 most important elements in the human body (approx. 96%). Symbol Name % 1 O oxygen 65 2 C carbon 18 3 H hydrogen 10 4 N nitrogen 3 ii. An additional 7 elements are also very important (approx. 3.99%) 5 Ca Calcium 2 6 P Phosphorus 1.1 7 K Potassium 0.35 8 S Sulfur 0.25 9 Na Sodium 0.15 10 Cl Chlorine 0.15 11 Mg Magnesium 0.05 -- These 11 elements make up nearly 100%. iii. 14 Trace Elements required in very small amounts (< 0.01%) 12 Fe Iron 0.004 13 I Iodine 0.0004 
For further discussion of elements, click on the periodic table below. (Students in F-2-F classes will do this in the laboratory.) Source: http://www.rsc.org/periodic-table Answer this question: The 4 most important elements in the human body?  The Atom - - - Introduction to the Atom (Khan Academy You Tube) - - -COMMENT ON THE YOUTUBE: Man, you're amazing! I am taking Chemistry for Highschool right now and it doesn't really make any? sense. So when ever I get stumped I know that I can ALWAYS get help from you! You have made Chemistry more interesting for me! Thank you SO much! You rock and I'd recommend you to ANYONE! :) Thanks again! Introduction to the atom Source: https://www.youtube.com/watch?v=1xSQlwWGT8M Subatomic Particles The atom is the smallest part of an element. Atoms consist of subatomic particles. The three best known include positively charged protons, uncharged neutrons, and negatively charged electrons. Protons and neutrons are located in the nucleus of an atom, and electrons move around the nucleus. Most of an atom is empty space.
  def. Atom: The smallest part of an element that still acts like that element, that cannot be divided by chemical means. (It can be divided by physical means into subatomic particles.) • Atoms are composed of 3 sub-atomic particles. NEUTRON -- no charge, 1 AMU (atomic mass unit) PROTON -- + charge, 1 AMU (atomic mass unit) ELECTRON -- - charge, negligible weight (much less than an AMU)
• If separated these particles will no longer act like the element they used to form: Ions Normally an atom is neutral in charge. When electrons are added to or removed from the atom it becomes positively or negatively charged -- an Ion-- Protons (+ charge) are in an atom normally balanced with the electrons (- charge) Example: the elements forming table salt, NaCl, Sodium Chloride (Sodium Na, and Chlorine Cl) gained electrons = negative ion Cl- Chlorine lost electrons = positive ion Na+ Sodium def. Isotope: One of several atomic forms of an element, each containing a different number of neutrons Review: Different # of electrons: Ion Different # of neutrons: Isotope Different # of protons: Element
Isotopes are atoms of the same element , have the same number of protons, but differ in the number of neutrons. For example carbon 12 has six neutrons (and six protons; 6+6=12), carbon 13 has seven neutrons (and six protons; 6+7=13), ands carbon 14 has eight neutrons (and six protons; 6+8=14).  Isotopes for medicinal use Some isotopes are unstable and break down to other stable isotopes over time. When they break down they give of radiation, which can be harmful, but also used direct or indirect, as tracers in the medical industry, for radiation treatment to kill fungi and bacteria on food, for radiation treatment of cancer, and for measuring the age of rocks. Measuring the age of rock is important to date fossils, and have been helpful to establish the age of the Earth.
The Age of Our World Made Easy (estimating the age of the Earth with isotopes) "Methods of dating easily explained, that clearly prove the age of the Earth and our universe. Part of the "Made Easy" series that explains science in clear and simple terms. A must for people who think the world is just 6,000 years old." Source: https://www.youtube.com/watch?v=w5369-OobM4  Chemical Properties of Elements Atom do usually not exist alone -- the react (bind) to other elements -- e.g., H. Naturally occurring hydrogen: H2
• Noble gases: Inactive elements, also called inert gases, that does not participate in chemical reactions. do not have room for extra electrons -- they cannot form bonds with other elements, with "filled" outermost shells tend to be non-reactive with other atoms. -- Helium He, Neon Ne, Argon Ar, Krypton Kr, Xenon Xe, Radon Rn all occur as single atoms.
•Other elements: have one or more unfilled spaces for electrons (orbitals) form bonds with other atoms
• Elements with different behaviors are placed at different locations in the periodic table.
• The most important shell is the valence shell, the outermost shell -- the shell that participates in chemical bonds. This shell is for most elements stable when having eight (8) electrons -- the so called "octet rule". def. Octet rule: The observation that an atom is most stable when its outer shell is complete and contains eight electrons; exception are hydrogen and Helium which requires only two electrons in the outer shell to have a completed shell. Answer this question: Number of electrons in the valence shell of an atom with atomic number 6?
Periodic table (abbreviated version). Source: Mader and Windelspecht. Essentials of Biology.  Molecules --- There are two types of molecules -- naturally occurring elements and compounds. They exists when two or more elements have bonded together to form molecules -- the smallest part of a compound that still has the properties of the particular compound. Water H2O is a molecule that contains two hydrogen atoms and one oxygen atom. Naturally Occurring Elements vs. Compoundsi. Naturally occurring elements H2 Hydrogen gas (H-H) O2 Oxygen gas (O-O)
Note: Inert gases are also naturally occurring elements but occur as single atoms.
CO2 Carbon dioxide (O-C-O)
NaCl Sodium Chloride (Table salt)
Chemical Bonds Compounds are held together by chemical bonds. In ionic bonds, charged particles called ions are held together because they are attracted to one another by opposite charges. In covalent bonds atoms are held together because they share electrons. Ionic bonds and covalent bonds are strong bonds. Ionic Bondsdef. Ionic bond: Bond formed by the force between ions of opposite charge. -- one atom attracts the electrons more than the other atom one atom gains one or more electrons ‹ positively charged one atom loses one or more electrons ‹ negatively charged -- opposite charged ions ‹ positive & negative attract each other ‹ bond  In polar covalent bonds, the sharing of electrons is not equal. If the molecule is "polar" (having slightly charged poles), the more electronegative atom carries a slightly negative charge and the other atom carries a slightly positive charge. (These charges are not the same as ionic charges.) Covalent Bondsdef. Covalent bond: Bond formed by the sharing of one or more electrons between atoms or group of atoms. -- both atoms attract the electrons equally   Hydrogen Bondsdef. Hydrogen bond: Bond formed by the weak charged attractions when an electropositive hydrogen atom in a polar covalent bond is attracted to a neighboring electronegative atom, and therefore interacts weakly with this neighboring atom. -- bond between a slightly positive hydrogen atom & another slightly negative atom in a POLAR COVALENT BOND
-- weak bonds  Chemistry of Water --- • Many chemical reactions in living things require water (as a reactant). • Organisms on Earth are made mostly of water: - adult human 40-60% of body weight - infant human 75% of body weight • Water is a polar molecule (Oxygen slightly more electronegative than hydrogen) -- form Hydrogen onds
Source: https://www.youtube.com/watch?v=iOOvX0jmhJ4 Important Properties of Water due to polarity and hydrogen bonds Water is a polar molecule, which allows a weak bond called hydrogen bond to occur between water molecules. Polarity and hydrogen bonding account for waters unique properties important for living organisms on Earth.
 High specific heat Solvent Cohesion Capillary action Density (less dense as a solid -- ice floats)
 When water ionizes, it releases hydrogen ions, and hydroxide ions. Water solutions that release more hydrogen ions are called acids, and water solutions that release more hydroxide are called bases. Lemon juice, vinegar, tomato juice, and coffee are acidic solutions. Milk of magnesia, soap, and ammonia are basic solution.
Example of strong acids:H2S04 -- Sulfuric Acid HNO3 -- Nitric Acid Acids, Bases, and the pH Scale The pH scale is used to indicate the acidity and basidity (also called alkalinity) of a water solution. The scale ranges from 0 to 14. A pH of 7 represents a neutral state in which the hydrogen and hydroxide ion concentrations are equal. A pH below 7 is acidic, and a pH above 7 is basic. The figure of a pH scale in your textbook illustrates some common solutions and their pH.
   Source: http://education-portal.com/cimages/multimages/16/neutral2a.png Neutralization Reaction:
   
A buffer is an important chemical that keeps pH within normal limits by picking up excess of the chemicals that causes acidic conditions. In living things, the pH of body fluids is maintained within a narrow range, or else health suffers, e.g., Acidosis (increased acidity in the blood and other body tissue). The normal pH of blood is about 7.4, just slightly basic. Buffers help keep the pH within normal limits because they take up excess hydrogen ions or hydroxide ions.   Acid rain Acid deposition, in the form of rain, snow, for, or ash, occurs because certain gas pollutants enter the atmosphere from burning of fossil fuels. The pollutants, N02 (nitrogen dioxide) and SO3 (sulphur trioxide) combine with water vapor in the atmosphere to form acids, HNO3 (nitric acid) and H2SO4 (sulfuric acid), that eventually return to Earth. Acid deposition has drastically affected forests and lakes in northern Europe, Canada, and the northeastern United States because their soils are naturally acidic. Acid deposition reduces agricultural yields and corrodes marble, metal, and stonework.    Nitrogen dioxide concentrations as measured from satellite 2002-2004. Source: http://en.wikipedia.org/wiki/Air_pollution#mediaviewer/File:Global_air_pollution_map.png (For further reading about this problem, see the ecology chapters in your textbook, or use Google.) Matter is made of atoms and all matter consists of various combinations of 92 elements. Living things consists primarily of eight of these elements -- oxygen, carbon, hydrogen, nitrogen, , calcium, phosphorus, potassium and sulfur -- with oxygen, carbon and hydrogen the three most common. A biology student needs to understand some basic chemistry -- the subatomic, atomic, molecular, and macromolecular levels of biological organization, in order to understand the variety of processes unique to life (see previous chapter). The next chapter discusses the important carbon atom, how it combines covalently (forms covalent bonds via sharing of electrons) with other elements in our cells to form unique molecules -- important for life -- called organic molecules, or macromolecules.
STAY TUNED. Links to the self-review quiz will soon be uploaded...
ACTIVITY: Figure Drawings: Atomic Structure The figure on the screen is of Carbon. Draw the figure on the paper and label the parts  The Carbon Atom. Used for educational purposes. Source: http://www.geojeff.org/images/carbon-atom.jpg |
