Module 4 Review

1. Module 4 Review

2. Module 4 Review

3. Module 4. 01 Atomic Theory Review • *Matter-is anything that has mass and takes up space. • *Element-substances could not be divided into other substances by any means. • *Atom-The smallest unit of an element • subatomic particles –is Protons, neutrons, and electrons • *Proton-subatomic particle that has a positive (+) charge. It has a mass number of 1 and is always located in the nucleus.

4. Module 4. 01 Atomic Theory Review • *Neutron-is a subatomic particle meaning it has no charge. It has a mass of number 1 and is always located in the nucleus. • *Electron-is a subatomic particle with a negative charge (-). It is much smaller than the proton and neutron, and has a mass of number 0. The electron is located cloud that surrounds the nucleus. • *Nucleus-the center of the atom, there is a very small region. The nucleus contains the protons and neutron.

5. Module 4. 01 Atomic Theory Review • *Electron Cloud-the area around the nucleus. This area makes up the majority of the volume of the nucleus. This is also mostly empty space and constantly moving.

6. Examples of Matter

7. Review 4.02 Atomic Model-Dalton’s Theory • * All matter is made of atoms. • *Scientists still hold this to be true. All matter that has been studied and observed seems to be made up of atoms. • *All atoms of a given element are the same. • *We now believe that atoms of the same element have the same number of protons. However, you will learn in later lessons that atoms of the same element may have different numbers of neutrons. Atoms with the same number of protons and different number of neutrons are called isotopes. • *Different elements are made up of different atoms. • *Scientists still hold this statement to be true. Atoms of different elements have different numbers of protons. The number of protons in an atom is used to identify the element.

8. Review 4.02 Atomic Model-Dalton’s Theory • *Atoms cannot be divided into smaller pieces. • *We now know that atoms are made up of subatomic particles: protons, neutrons, and electrons. • *Atoms of different elements combine in whole number ratios to make compounds. • *As you will see in the next few lessons, atoms bond together in whole number ratios to make an almost unlimited amount of different compounds.

9. 4.02 Atomic Model ScientistsThomson • *At the beginning of the 20th Century, Thomson’s atomic model was accepted as the correct representation of the atom. In Thomson’s model, negatively charged electrons were dispersed inside an area of positive charge. The positive and negative charges canceled out each other, resulting in a neutral atom.

10. 4.02 Atomic Model ScientistsRutherford • *Ernest Rutherford • an English scientist, designed an experiment to test Thomson’s atomic model. Rutherford planned to fire heavy, positively charged, fast particles on a very thin metal foil, made of gold. A screen was placed around the gold foil. This foil was sensitive to particles that were fired and would show how the particles were affected by the foil. This set up was like firing a heavy cannon on a tissue paper. Rutherford did not expect the particles to get effected at all.

11. 4.02 Atomic Model Scientists Bohr • *Bohrstated electrons used specific orbits while moving around the nucleus. An electron could jump to a higher orbit if it gained energy or a lower orbit if it lost energy. Bohr’s model meant laws of classical physics did not apply to atoms. Bohr’s model was the beginning of a new field of study, called quantum physics.

12. 4.02 Atomic Model ScientistReview • *Thomson’s model, consisting of negatively charged electrons inside an area of positive charge, was accepted as the correct representation at the beginning of 20th century.

13. 4.02 Atomic Model ScientistReview • *Rutherford proved the atom had a very dense core by his gold foil experiment. Investigating further, scientists discovered that an atom consisted of a nucleus containing protons and neutrons, and electrons that orbit around that nucleus

14. 4.02 Atomic Model ScientistReview • *Latest models state it is not possible to determine exact location of an electron. Therefore, scientists define an electron cloud as the location where an electron is most likely to be found

15. 4.03 Introduction to Periodic Table • *In 1869, Dmitri Mendeleev, a Russian chemist, set out to organize the known elements according to their properties. He noticed that when elements were arranged by increasing mass, there were repeated or periodic patterns in their properties.

16. 4.03 Moseley • *In 1911, the English scientist Henry Moseley discovered something that helped explain why some of the elements were out of order by mass. • *Moseleydiscovered that the periodic pattern was determined by the number of protons in the element’s nucleus, not the mass of the atoms.

17. 4.03 Periodic Table • *His discovery led to the definition of the term atomic number . The atomic number represents the number of protons in an atom of a given element. • *Today, scientists still recognize that the atomic number as the basis of the organization of the periodic table.

18. 4.03 Properties of Metals • *Properties of Metals • *Metalsare good conductors of heat and electricity. • *They are also solids at room temperature. • *Metals are ductile. Ductility is the ability to be drawn into wire. • *Metals are malleable. Malleability is the ability to be rolled into thin sheets. • *Metals also have a distinct shiny look which is called metallic luster.

19. 4.03 Properties of Nonmetals • *As their name suggests, NON-metals exhibit properties that are just the opposite of metals. • *Non-metals are poor conductors of both electricity and heat. • *Non-metals are generally used as insulators. • *At room temperature, non-metals can be either solids or gases. • *Non-metals are not ductile. • *Non-metals are not malleable. • *Non-metals are mainly either opaque or transparent.

20. 4.03 Properties of Metalloids • *The physical properties of metalloids lie between those of metals and non-metals. • *Metalloids are moderate conductors of electricity. • *Metalloids are solid at room temperature. • *Metalloids can be ductile to varying degrees. • *Metalloids can be malleable to varying degrees. • *Metalloids can show a metallic luster in varying degrees

21. 4.03 Semiconductor • *Semi means half or partial. So semiconductors (metalloids) have electrical conductivity half way between those of a conductor and an insulator.

22. 4.04Periodic Table • *The elements are arranged in order of increasing atomic number. • *The elements are grouped in columns with other elements with similar properties.

23. 4.04Protons • Protons • *The positive subatomic particle • *The atomic number is the number of protons in all atoms of the element

24. 4.04 Electrons • *Electrons-The negative subatomic particle • *The number of electrons equals the number of protons in a neutral atom • *This means that the atomic number tells us the number of electrons and protons

25. 4.04 Neutrons • *Neutron- The neutral subatomic particle • *The mass number minus the atomic number tells you the number of neutrons in an atom

26. 4.04 Energy levels • *Each electron is localized to a specific area, the energy level, within the electron cloud. • * Each electron is localized to a specific area, the energy level, within the electron cloud.

27. 4.04 Valence electrons • *These outermost electrons • *The number of valence electrons in the outermost energy level of an element determines if and how the element will react with other elements.

28. 4.04 Examples of Valence Electrons and Energy Level

29. 4.05 Compounds • *A compound is formed when two or more atoms combine together to form a new substance with unique properties.

30. 4.05 Ionic Compound • *An ionic bond is the chemical bond that results from an electrostatic attraction that occurs when metal atoms lose electrons to nonmetal atoms. • *An ionic compound can also be called a salt . Table salt, NaCl, is not the only salt! Ionic compounds have high melting points, are solid at room temperature, and usually dissolve well in water. • *You can identify a compound that contains ionic bonds because it will contain atoms of a metal bonded with atoms of a nonmetal. Examples include NaCl, Al2O3, and CaCl2.

31. 4.05 Ionic Compound

32. 4.05 Covalent Compound • *A covalent bond is a chemical bond that is formed by the sharing of electrons between atoms. • *Covalent compounds are also called molecules. Molecules can be solids, liquids or gases at room temperature. They also have much lower melting points than ionic compounds.

33. 4.05 Covalent Compound • *You can identify a compound that contains covalent bonds because it is made up of only nonmetals. Examples include H2O, CO, CH4, and NH3.

34. 4.05 Covalent Compound

35. 4.06 Properties of Compounds • *Acids • *Have a sour taste.Grapefruit is an example of an acidic fruit. • *React with metals. If you have ever encountered a corroded battery, you have witnessed how acids react with metal. • *Can cause stinging on skin or membranes.Heart burn is an example of stomach acid stinging the lining of the esophagus.

36. 4.06 Properties of Compounds • *An acid is a molecular compound that contains hydrogen and produces hydrogen ions, H+, when it breaks apart in solution. • *HClis hydrochloric acid. When it dissolves in water to make an acidic solution, it breaks apart and gives off H+ particles. • HCl H+ + Cl- • *Other examples of acids include: • Sulfuric acid, H2SO4, which is found in batteries and acid rain • Acetic acid, HC2H3O2, found in vinegar • Citric acid, C6H8O7, found in citrus fruits like lemons and limes • *Everyday items that contain acids include: • Lemons • Oranges • Lettuce • Tomatoes

37. 4.06 Examples of Acids

38. 4.06 Properties of Compounds • *Bases • *Have a bitter taste.Mustard and many medications are bitter because of the bases they contain. • *Feel slippery to the touch.Laundry detergent has a very slippery feel because of its basic ingredients. • *Can be irritating to nose and eyes.*Ammonia is an example of a base that can be very irritating to the nose, eyes, and skin.

39. 4.06 Bases • *A base is a compound that has OH in its formula and produces hydroxide ions, OH-, when it breaks apart in solution. • *NaOHis sodium hydroxide, a base. When it dissolves in water the oxygen and hydrogen atoms break off as OH-particles. • NaOH Na+ + OH- • *Other examples of bases include: • *Potassium hydroxide, KOH, is used in the production of soaps and biodiesel • *Calcium hydroxide, Ca(OH)2, is also known as lime. It is used in the production of plaster, treatment of root canals, and many other industrial uses. • *Everyday items that contain bases include: • Soap • Toothpaste • Ammonia

40. 4.06 Examples of Bases

41. 4.06 Advance pH scale • *An acidic solution has more H+ ions than OH- ions. • *A neutral solution has equal amounts of H+ and OH-. • *A basic solution has fewer H+ ions than OH- ions.

42. 4.06 Advance pH Scale • *The measure of the acidity of a solution is called pH . This measurement is based on the amount of hydrogen ions present. • *If the pH of a solution is less than 7, it is acidic. The lower the pH value is, the more acidic the solution because of the greater amount of H+ ions. • *If the pH of a solution is 7, it is a neutral solution. This means that the concentrations of H+ ions and OH- ions are equal. • *If the pH of a solution is greater than 7, it is basic. The higher the pH value, the more basic and the greater the amount of OH- ions.

43. 4.06 Advance pH Scale • *1.6 pH value - Stomach Fluid • *2.8 pH value - Vinegar • *4.2 pH value - Tomatoes • *5.0 pH value - Coffee • *7.0 pH value - Pure Water • *8.2 pH value - Sea Water • *9.2 pH value - Baking Soda • *11.4 pH value - Household Ammonia • *12.8 pH value - Household Bleach

44. 4.06 Advance pH Scale

45. 4.06 Advance Test Knowledge • *High number of H+ ions - Acid • *Low pH value - Acid • *More H+ than OH- - Acid • *High pH value - Base • *High number of OH- ions - Base • *More OH- than H+ - Base

46. 4.06 Are they a Solution, Compound or Mixture • *Salt - is a compound, and compounds are pure substances. • *Soda Water - is a mixture of gaseous carbon dioxide and liquid water. *Mixture Brass - is an alloy or a mixture of metals. • *Brassis made from mixing the elements copper and zinc. Mixture • *Aluminum Foil - is a pure element, found on the periodic table. Pure Solution • *Granite- is a mixture of different materials that create those neat patterns in the rock. Mixture • *Iron- is a pure element found on the periodic table. Pure Solution • *Steel - is an alloy, a mixture of iron and carbon. Mixture • *Milk- is a mixture of water, fat, and other substances, such as calcium. Mixture

47. 4.07 Difference Between Heterogenous and Homogenous Mixture • *homo-: This part of the word comes from the prefix hom-, which means same. A homogeneous sample is the same throughout the sample. • *–geneousin homogeneous: This part of the word comes from the root gen(os). In this context, it means kind. This helps us understand that a homogeneous substance is of the same kind throughout. It is uniform in its composition. • *hetero-: This part of the word comes from the prefix heter(o)-, which means different or other. A heterogeneous substance is different in various portions of the sample. • *–geneousin heterogeneous: This part of the word comes from the root gen(os). In this context, it means kind. This links with the prefix to tell us that a heterogeneous substance is of a different kind throughout. It is not uniform in its composition.

48. 4.07 Review

49. 4.07 Review Pure Substance or Mixture

50. 4.07 Mixtures, Solutions, and Pure Substances Practice • Classify each of the following as a solution, heterogeneous mixture, element or compound. • *A mixture that is uniform throughout - solution • *Alloys are an example - solution • *Marble is an example - heterogeneous mixture • *Aluminum is an example - element • *Sodium chloride is an example - compound • *A pure substance that can be broken down by chemical means - compound • *Sand and water is an example - heterogeneous mixture • *A pure substance that cannot be broken down - element • *Air is an example - solution • *Carbon is an example - element • *A mixture that is not uniform throughout - heterogeneous mixture • *Carbon monoxide is an example – compound