1 / 66

Elements of Chemistry

Elements of Chemistry. The Central Science. Science is useful to our lives. It answers questions like… What is the ocean made of? How does gasoline serve as a fuel? How does your body use food to move?. Chemistry. Chemistry - the study of matter and the transformation it can undergo

diane
Download Presentation

Elements of Chemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Elements of Chemistry The Central Science

  2. Science is useful to our lives • It answers questions like… • What is the ocean made of? • How does gasoline serve as a fuel? • How does your body use food to move?

  3. Chemistry • Chemistry - the study of matter and the transformation it can undergo • Matter is anything that occupies space • Therefore chemistry is very broad!

  4. Chemistry as the Central Science • Chemistry touches all other sciences • Builds up from physics – the principles of physics are applied to the atom • Foundation for biology of living things • Foundation for Earth Sciences

  5. Scientific Research • Activity aimed at discovering and interpreting new knowledge • Two types: • Basic • Applied

  6. Basic Research • Leads to greater understanding of how the natural world operates • Foundation of knowledge leads to useful applications

  7. Applied Research • Developing applications from our understanding of the natural world • Chemists focus on applied research • Medicine • Food • Water • Shelter

  8. Past Century Advances have Impacted the Environment • We have harmed the environment by emptying waste into rivers, burying it underground and venting it into the air • Now involved in extensive efforts to clean it up! • For example: CFC’s

  9. Chemists have learned how to produce aspirin using petroleum as a starting material. • Is this basic or applied research? • Applied

  10. Atoms • Everything around us is made up of atoms • They are the smallest units of matter! • One grain of sand has 125 million trillion atoms!!!!

  11. Molecules • Atoms link together to form larger, but still incredibly small units of matter called molecules • Example: Two hydrogen atoms and one oxygen atom link together to form one molecule of water • One cup of water has over 1,000,000,000,000,000,000,000,000 molecules of water!!! (that’s a trillion trillion!)

  12. Levels of Magnification • Macroscopic • Can be seen, measured and handled • Microscopic • Seen only with a microscope • Used in biology

  13. Submicroscopic • Realm of atoms and molecules • Focus of chemistry • Chemistry studies all levels of magnification, but emphasizes on the submicroscopic

  14. Phases of Matter • Solid, liquid, and gaseous phases are distinguished by how the submicroscopic particles are held together

  15. SolidS • In solids, the attraction is so strong that the particles are together in some fixed 3D arrangement • Atoms / molecules are still moving, but only with Brownian motion • Perpetual jiggling from collisions between particles

  16. LiquidS (There is a mistake in your note here. Fix it to read as follows…) • Add heat to a solid until a certain temperature; increased vibrations disrupt the fixed arrangement • Gives rise to the liquid’s fluid mobility

  17. Gases • Further heating of a liquid increases particle movement until the attractions are unable to hold them together • Molecules separate, forming gas • Gases occupy much more space (volume) than solids or liquids • They can be squeezed into smaller volumes using pressure (aerosol cans)

  18. Physical Properties • The look or feel of a substance • Ex: Color, hardness, density, texture, phase • They can change when conditions change • If this happens, the substance’s composition does not change • Ex: When ice melts, it’s still H20

  19. Physical Change • Change in the physical property, but not the chemical composition • Rip • Phase change

  20. Is the melting of gold a physical change? • YES!!! Melting, the gold does not change the composition

  21. Chemical Properties • Chemical properties describe how one substance reacts with others or how a substance transforms

  22. New substance formed by the reaction of these chemicals with one another • CH4 + O2 > CO2 + 2H2O • Baking soda + vinegar > carbon dioxide + water • You eat food > build body tissue (you grow!)

  23. Cu + H2O + O2 > patina

  24. These transformations involve a change in the way atoms and molecules are bonded to one another • Chemical bond - the attraction between two atoms that hold them together in a molecule

  25. Example • Methane (CH4) = carbon with 4 hydrogen atoms attached • Oxygen (O2) = two oxygen atoms attached • When methane and oxygen react to produce carbon dioxide and water, they form new bonds with different partners • CH4 + 2 O2 CO2 + 2 H2O

  26. What are Bonds? • Covalent Bonds • Share electrons in their outermost electron shell • Valence electrons • Bonds between nonmetals and other nonmetals • Ex: O2 and H2O

  27. Ionic Bonds • Charged atoms / molecules attract (Ions) • Opposites attract • Loose or gain a valence electron in the outermost electron shell • Metal + Nonmetal • Ex: NaCl, KBr, CaCl2

  28. Chemical Change • Any change in a substance that involves a rearrangement of the way its atoms are bonded • Beginning materials are said to be reactants • They will react with each other to form new compounds

  29. Example • Copper reacts with silver nitrate to produce copper nitrate and silver • Methane reacts with oxygen to produce carbon dioxide and water

  30. Chemical Change = Chemical Reaction • Chemical reaction – new materials are formed by a change in the way atoms are bonded together

  31. Physical Change vs. Chemical Change SIMILARITIES: • Change in physical appearance and energy • Water looks different than ice • Physical change • Rust looks different than metal • Chemical change

  32. Physical Change vs. Chemical Change • SAME material, only new conditions • Typically less energy • Restore original conditions restores original appearance • No new chemical identity • Formation of a NEW material • Unique set of physical properties • Cannot restore original appearance without another chemical change Physical Change Chemical Change

  33. Example • Growth of 1 inch in a year. • Chemical or physical change? • CHEMICAL!!! Body is changing food into body tissue

  34. Elements • An element is made of only one type of atom! • Element is used in reference to an entire macroscopic or microscopic sample • Atom is used in reference to the submicroscopic particles in a sample • Elements are made of atoms; NOT vise versa

  35. Elemental Formula • Tells how many atoms are bound together in an element • Elements with basic units are individual atoms = Write the chemical symbol • For example: Au, Cu, Pb, K

  36. Elemental Formula (continued) • Elements in which basic units are two or more atoms bonded together = Chemical symbol + subscript • For example: All the –gens (oxygen O2, hydrogen H2 and nitrogen N2) • and all the –ines (fluorine F2, chlorine Cl2, bromine Br2, iodine I2, astatine At2) • and Sulfur S8

  37. Why is gold’s symbol not G? • Named a long time ago and given a Latin name (Aurum, Au) • Why is lead’s symbol not L? • Named a long time ago and given the Latin name plumbum (Pb)

  38. Oxygen we breathe (O2) is converted to ozone (O3) in the presence of an electric spark. • Is this a physical or chemical change? • Chemical

  39. 21. 5Elements Combine to form Compounds • Atoms from different elements bond to one another to form compounds • NaCl – table salt • NH3 – ammonia • CO2 – carbon dioxide • CO – carbon monoxide • H2O - water

  40. Chemical Formula • Write symbols for the number of each element in the compound • Elements closer to the left side of the periodic table are written first • If there is only one atom, no subscript is needed • The number 1 is always understood

  41. Examples • Sodium chloride = NaCl • One sodium for every chlorine • Calcium chloride = CaCl2 • One calcium for every two chlorines • Aluminum chloride = AlCl3 • One aluminum for every three chlorines

  42. Compound vs. Elemental Properties • Compounds have physical and chemical properties that are different than their elemental properties • Sulfur vs. Sulfur dioxide

  43. Example • Sodium chloride (table salt) is different than elemental sodium and chlorine • Sodium – soft metal, reacts violently with water • Chlorine – yellow-green gas, toxic • NaCl – translucent, brittle, colorless crystal, non-toxic essential to human life

  44. H2S is one of the smelliest compounds –the smell of ROTTEN EGGS is due to the hydrogen sulfide they release. • Do think elemental sulfur, S8, is just as smelly? • NO!!! Compounds are different than elements they are made from

  45. Chemical Formula • Remember -- Different elements combine to make new compounds with different properties • And if the same elements combine in different ratios – THIS MAKES DIFFERENT COMPOUNDS!!! • For Example: O2 –oxygen; needed by animals to breathe • O3 –ozone; which is poisonous to breathe

  46. 21.6 Chemical Reactions are represented by chemical equations • In chemical reactions, atoms rearrange to create one or more new compounds • This can be summed up in a written chemical equation

  47. 21.6 Chemical Equations • Reacting substances (reactants) are to the left of the arrow • Newly formed substances (products) are to the right of the arrow • REACTANTS PRODUCTS

  48. Chemical Equations • Reactants and Products are represented by their elemental or chemical formulas • Phases are shown with subscripts: • (s) for solid, (l) for liquid, (g) for gas • H2O(s), H2O(l), H2O(g) • Compounds dissolved in water are known as aqueous • NaCl(aq)

  49. Coefficients • Numbers placed in front of the reactants or products to show the ratio of combination or formation • Represent number of individual atoms or molecules • If NO coefficient, it is understood to be 1 • CH4 + 2O2 > CO2 + 2H2O

More Related