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Understanding Subatomic Particles and Atomic Structure in Chemistry

This comprehensive guide explores the fundamental concepts of subatomic particles, including protons, neutrons, and electrons, along with their respective properties such as actual mass and charge. It covers essential definitions, such as atomic number, mass number, and isotopes, while explaining how to identify and calculate the composition of atoms. Additionally, the guide distinguishes between ions and neutral atoms, elaborates on the modern periodic table structure, and describes the characteristics of metals, metalloids, and nonmetals. Ideal for students and enthusiasts seeking to deepen their understanding of chemistry.

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Understanding Subatomic Particles and Atomic Structure in Chemistry

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  1. CHEMISTRY!!!!

  2. Subatomic particles Actual mass (g) Relative mass Name Symbol Charge Electron e- -1 1/1840 9.11 x 10-28 Proton p+ +1 1 1.67 x 10-24 Neutron n0 0 1 1.67 x 10-24

  3. Counting the Pieces • Atomic Number = number of protons in the nucleus • # of protons determines kind of atom • The same as the number of electrons in the neutral atom. • Mass Number = the number of protons + neutrons. • These account for most of mass

  4. Counting the Pieces • Protons: equal to atomic number • Neutrons: Mass Number – Atomic Number • Electrons: In a neutral atom equal to atomic number

  5. Symbols • Contain the symbol of the element, the mass number and the atomic number.

  6. Symbols • Contain the symbol of the element, the mass number and the atomic number. Mass number X Atomic number

  7. Symbols • Find the • number of protons • number of neutrons • number of electrons • Atomic number • Mass Number 19 F 9

  8. Symbols • Find the • number of protons • number of neutrons • number of electrons • Atomic number • Mass Number 80 Br 35

  9. Symbols • if an element has an atomic number of 34 and a mass number of 78 what is the • number of protons • number of neutrons • number of electrons • Complete symbol

  10. Symbols • if an element has 91 protons and 140 neutrons what is the • Atomic number • Mass number • number of electrons • Complete symbol

  11. What if Atoms Aren’t Neutral • Ions: charged atoms resulting from the loss or gain of electrons

  12. What if Atoms Aren’t Neutral • Anion: negatively charged ion; result from gaining electrons • Take the number of electrons in a neutral atom and add the absolute value of the charge Identify: Number of Protons Number of Neutrons Number of Electrons 81 1- Br 35

  13. What if Atoms Aren’t Neutral • Cation: positively charged ion; result from the loss of electrons • Take the number of electrons in a neutral atom and subtract the value of the charge Identify: Number of Protons Number of Neutrons Number of Electrons 27 Al 3+ 13

  14. Isotopes • Atoms of the same element can have different numbers of neutrons • Different mass numbers • Called isotopes

  15. Naming Isotopes • We can also put the mass number after the name of the element. • carbon- 12 • carbon -14 • uranium-235

  16. Atomic Mass • How heavy is an atom of oxygen? • There are different kinds of oxygen atoms • We are more concerned with average atomic mass • Average atomic mass is based on abundance of each element in nature. • We don’t use grams because the numbers would be too small

  17. Measuring Atomic Mass • Unit is the Atomic Mass Unit (amu) • It is one twelfth the mass of a carbon-12 atom • Each isotope has its own atomic mass, thus we determine the average from percent abundance

  18. Atomic Mass • Is not a whole number because it is an average. • are the decimal numbers on the periodic table.

  19. Modern Periodic Table • The modern periodic table consists of Rows and Columns • Rows - • Horizontal • Also known as Periods • Numbered 1-7 • Columns - • Vertical • Also known as Groups and Families • Numbered 1-18

  20. Metals • The most common class of elements is Metals • Metals become cations • What is a cation? How are they formed? • Positively charged atom - Lose electrons • Metals are generally solid (except Hg), conductive of heat and electricity, malleable, ductile, and shiny

  21. Alkali Metals • Group 1 elements are known as Alkali Metals • Alkali metals include Li, Na, K, Rb, Cs, Fr • Alkali metals are generally dull, soft, and reactive – rarely found as free elements

  22. Alkaline Earth Metals • Group 2 elements are known as Alkaline Earth Metals • Alkaline earth metals include Be, Mg, Ca, Sr, Ba, and Ra • Alkaline earth metals are harder, denser, and stronger than alkali metals • Less reactive than alkali metals, but still rarely found as free elements

  23. Transition Metals • Elements in groups 3-12 (3B-2B) are known as Transition Metals • Transition metals include Mn, Fe, Ag, Au, Mo, etc. • Lanthanide and Actinide Series elements fill in the f orbitals – known as inner transition elements

  24. Metalloids • Elements that border the staircase on the periodic table are known as Metalloids • Metalloids include: B, Si, Ge, As, Sb, Te, Po, At • Metalloids have properties of both metals and nonmetals

  25. Nonmetals • Nonmetals are found to the right of the staircase on the periodic table • Nonmetals generally become anions • What is an Anion? How are they formed? • Negatively charged atom - Gain electrons • Nonmetals are often gases or dull, brittle solids • Nonmetals generally show poor conductivity, ductility, and malleability

  26. Halogens • Group 17 elements are known as Halogens • Halogens include F, Cl, Br, and I • Halogens are the most reactive nonmetals – often found in compounds

  27. Noble Gases • Elements in group 18 are known as Noble Gases • Noble Gases include He, Ne, Ar, Kr, Xe, Rn • Noble gases are extremely unreactive

  28. Legend

  29. Pure Substances • Cannot be physically separated • Every sample has the same characteristics and they can be used to identify a substance

  30. Elements • Are made up of ONE type of atom • Atoms are the smallest unit of an element that maintains the chemical identity of that element • They can be found on the Periodic Table • Examples: Carbon, Nitrogen, Calcium

  31. Compounds • Can be broken down into simple stable substances • Are made up of two or more types of atoms that are chemically bonded • Examples: Water (H2O), sugar (C12H22O11)

  32. Mixtures • A blend of two or more kinds of matter, each which retains its own identity and properties

  33. Homogeneous Mixtures • Have uniform composition • Also known as SOLUTIONS • Examples: salt water, tea

  34. Solutions • ALLOYS are solid solutions that contain at least 1 metal • They are blended together so that they have more desirable properties • Some alloys you may know are: • Stainless Steel: iron, chromium, and zinc • Brass: zinc and copper • Bronze: tin and copper • Sterling Silver: copper and silver

  35. Heterogeneous Mixtures • Do not have uniform composition • You can see the particles in them • Examples: • Sand on the beach (contains sand, shells, rocks, bugs, etc) • Soil (contains dirt, rocks, worms, etc) • Chicken Soup (contains water, chicken, veggies etc)

  36. Suspensions • A heterogeneous mixture where the solid particles eventually settle out of solution • Examples: • Muddy water • Mixtures of two solids • Paint

  37. Properties of Matter • All pure substances have characteristic properties • Properties are used to distinguish between substances • Properties are also used to separate substances

  38. Physical Properties • A Physical Property is a characteristic that can be observed or measured without changing the composition of the substance • Physical properties describe the substance itself • Examples • Physical State • Color • Mass, shape, length • Magnetic properties

  39. Chemical Properties • A Chemical Propertyindicates how a substance will react with another • Chemical properties cannot be determined without changing the identity of the substance • Examples: • Iron Rusting • Silver Tarnishing

  40. Physical Changes • A Physical Change is a change in a substance that does not alter the substance’s identity • Examples: • Grinding • Cutting • Melting • Boiling

  41. Chemical Changes • A change in which one or more substances are converted into different substances is called a Chemical Change • Signs of a Chemical Change: • Color Change • Gas is Released • Temperature Change • Precipitate – Solid falls out of solution • Substance Disappears

  42. Electrons • Electrons fill in an atom in energy levels • Electrons occupy the LOWEST available energy level • Energy Levels hold limited amounts of electrons • 1st Level – 2 electrons • 2nd Level – 8 electrons • 3rd Level – 18 electrons • 4th Level – 32 electrons

  43. Chlorine (Cl) P = 17 N = 18 E = 17

  44. Nitrogen (N) P = 7 N = 7 E = 7

  45. Aluminum (Al) P = 13 N = 14 E = 13

  46. Valence Electrons • Electrons in outermost shell that determine chemical behavior • Maximum of 8 valence electrons • Atoms with same valence electrons will act similarly • Group 1 elements? • 1 valence electron • Group 17 elements? • 7 valence electrons

  47. How Atoms Combine • Two or more atoms that are chemically combined make up a compound • The combination results in a chemical bond, a force which holds elements together in a compound

  48. Covalent Bonds • Covalent Bonds are formed when atoms in a compound share electrons • Molecule – two or more atoms held together by a covalent bond • Usually occurs between nonmetals

  49. Covalent Bonding in Water

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