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Atoms, Molecules and Ions

Atoms, Molecules and Ions

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Atoms, Molecules and Ions

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  1. Atoms, Molecules and Ions Chapter 2

  2. Dalton’s Atom • What are the main components of Dalton’s theory? • Elements are composed of atoms, which are specific to that element • Compounds are made up of more than one element • Atoms (matter) cannot be created or destroyed

  3. Atomic Structure • What is an atom? • A basic unit of an element that can react with itself or other elements • All atoms of a given element are absolutely identical in every way

  4. Atomic Structure • What are the different subatomic particles? • Electrons • e- • Protons • p+ • Neutrons • n0 • Protons and neutrons can be broken down into quarks • String Theory?

  5. Subatomic • What are the important characteristics of electrons? • What is the nucleus? • Location: • Outside the nucleus • Charge: • -1 • Mass: • 9.109 × 10-31 kg • Allow elements to chemically bond and react • An incredibly dense center of an atom

  6. Subatomic • What are the important characteristics of • …protons? • …neutrons? • Location: • In the nucleus • Charge: • +1 • Mass: • 1.673 × 10-27 kg • Location: • In the nucleus • Charge: • 0 • Mass: • 1.675 × 10-27 kg

  7. Atomic number • If an element has 12 protons, what is the atomic number (Z) of that element? • 12, atomic number (Z) is how many protons are in the nucleus • Z also tells us how many electrons there are if the atom is neutral • Elements are defined and organized based on their atomic number

  8. Atomic Mass and Number • What does the mass number (A) tell you? • How can we determine the number of neutrons using Z and A? • The total mass of the atom • We assume that electrons have no mass • Neutrons = A – Z (round down)

  9. Atomic Mass and Number

  10. Atomic Mass and Number • Can the number of subatomic particles change without changing the element? • Electrons: Yes • Called ions • Neutrons: Yes • Called isotopes • Protons: No • Different Z = different element

  11. Atomic Mass and Number • How are isotopes of the same element similar and different? • Different number of neutrons and masses • Similar reactivity

  12. Atomic Mass and Number • How are ions of the same element different from each other? • Different number of electrons • Charged +/- • Affects how an element bonds

  13. Atomic Mass and Number Practice

  14. Atomic Mass and Number Practice • Write the appropriate symbol for each of the following isotopes: • Z = 64, A = 186 • Z = 80, A = 201 • Z = 27, A = 59 • Z = 54, A = 130

  15. The Periodic Table Of Elements Song

  16. Person who gives out tickets to traffic court. • Half a dime. • What they do with dead people. • What all that glitters is not. • What you do to cattle that get away. • What a horse has to be if he won’t go for water. • Lone Ranger’s horse. • A really “pressing” thing. • What most lectures are. • Twice a half-nium. • Prisoner who sniffed laughing gas. • Soldier from Troy who only fights after dark. • What a doctor should do for his patients (2 available answers). • What I do is none of your _______________! • What the police do to drug houses? • How we refer to the guy who had his stomach removed. • What the Lone Ranger did to his horse.

  17. The Periodic Table • How is the periodic table arranged? • Increasing atomic number • Similar chemical and physical properties • Horizontal rows/periods • Vertical columns or families/groups

  18. The Periodic Table • What is the difference between metals, metalloids and nonmetals? • Metals – good conductor of heat and electricity • Nonmetals – poor conductor of heat and electricity • Metalloids (semimetals) – contains characteristics of both metals and nonmetals • “staircase”

  19. The Periodic Table • What are some of the group names? • 1 – Alkali metals (except H) • 2 – Alkaline earth metals • 3 –12 - Transition metals • 13 – Boron family • 14 – Carbon family • 15 – Nitrogen family • 16 – Oxygen family • 17 – Halogens (Halides) • 18 – Noble gases

  20. Element 119?

  21. Molecules • What is the difference between monatomic, diatomic and polyatomic? • Monatomic – only one atom • Noble gases are monatomic atoms • Diatomic – contain only two atoms • Ex. H2 or CO • Polyatomic - contains more than two atoms • Ex. H2O and O3

  22. Molecules • What substances can we call molecules? • Any diatomic or polyatomic combination of atoms • Be careful, a molecule can be an element or a compound • Cl2 vs. O3 vs. H2O

  23. Ions • How can we indicate a change in the number of electrons? • Assign charges • Charged atoms are called ions • Positive ion – cation • Negative ion – anion • Electrons have a charge of -1, so be careful when you +/-

  24. Molecules and Ions • What is the connection between molecules and ions? • Monatomic ion – a charged atom • Polyatomic ion – a charged molecule • Need to be able to recognize the common polyatomic ions (pg. 55) • Ex. OH1- and CN1-

  25. Molecules and Ions • How do we determine charge? • Determine the # of electrons in the neutral state • Determine how many electrons are present • Do the math and assign the charge, this is called the oxidation state(an element may have more than one) Note: Table 8 in your data booklet has the common oxidation states of each element

  26. Molecules and Ions • If an ion of Sodium (Na) has 10 electrons, what is the charge? • If an ion of Nitrogen (N) has 10 electrons, what is the charge? • Lost 1 electron • Na1+ • Cation • Gained 3 electrons • N3- • Anion

  27. Molecules and Ions • Determine whether electrons were gained or lost and how many remain: • Mg2+ • Fe3+ • C4- • I7- • Ar0 • Mg2+ lost 2, 10 remain • Fe3+ lost 3, 23 remain • C4- gained 4, 10 remain • I7- gained 7, 60 remain • Ar0, gained/lost none, 18 remain

  28. Chemical Formulas • What does a chemical (molecular) formula tell you? • What elements the chemical contains • How many atoms of each element there are • How the atoms are arranged (sort of) • The masses of the elements within the compound

  29. Chemical Formulas • What is the formula for 2 dihydrogen monoxide molecules? • 2H2O • 2 hydrogen/molecule • 1 oxygen/molecule • Subscript denotes how much of that element • Coefficient denotes how many of that molecule

  30. Chemical Formulas • How can we change a formula into an empirical formula? • What is the empirical formula of Fe4O6 and NH3 ? • Reduce the ratio of atoms to the smallest possible • Ex. Hydrogen Peroxide – H2O2 • 1:1 Ratio • Empirical – HO • Fe2O3 • NH3 (smallest ratio)

  31. Chemical Formulas • How do we make sure that a chemical formula is neutral (no charge)? • The net charge of the ions in the molecule must equal zero • If the charges are different we use the subscripts to balance them

  32. Chemical Formulas • What is the chemical formula for sodium chloride? • Na and Cl • Na1+ and Cl1- • “swap and drop” means swap the charges and drop them to subscripts • Na1Cl1, but we do not write the 1’s • NaCl

  33. Chemical Formulas • What is the formula for magnesium bromide? • Mg and Br • Mg2+ and Br1- • “swap and drop” • Mg1Br2, but we do not write the 1 • MgBr2

  34. Chemical Formulas • What happens when we have a polyatomic ion? • What is the formula for potassium cyanide? (use table 2.3) • Treat the polyatomic as one piece with one charge • K and CN • K1+ and CN1- • “swap and drop” • KCN

  35. Chemical Formulas • What are the formulas of the following chemicals: • Potassium Iodide • Aluminum chloride • Magnesium hydroxide • Sodium hydrogen carbonate • KI • AlCl3 • Mg(OH)2 • NaHCO3

  36. Chemical Formulas • What are the oxidation states of each element in the following: Reverse swap and drop! • KOH • Al2O3 • FeCl3 • BeO • K1+ and OH1- • Al 3+ and O2- • Fe3+ and Cl1- • Be2+ and O2- • NOTE: There are rare times when “swap and drop” does not work, so always check your oxidation states to make sure that they make sense!

  37. Naming Compounds • What scientific word do we use for naming? • What is the difference between organic and inorganic compounds? • Nomenclature • Organics contain mainly hydrogen and carbon whereas inorganics do not • Have different naming systems

  38. Naming Compounds • What four categories can we divide inorganics into? • What is the composition of an ionic compound and what suffix do we use? • Ionic, Molecular, Acids and Bases and Hydrates • Made up of positive and negative ions • Usually between a metal and a non-metal • Suffix:-ide • Sodium Chloride

  39. Naming compounds • What are the two ways we name ionic compounds that have more than one oxidation state? • 1 – By their Latin root words • Ex. Iron • Ferrous • Ferric • 2 – Using roman numerals • Ex. Iron • Iron(II) or Fe(II) • Iron(III) or Fe (III)

  40. Naming compounds • How are molecular compounds different from ionic ones? • Molecular compounds are usually made up of only non-metals • Ionic compounds are made up of metals and non-metals

  41. Naming compounds • What prefixes and suffixes are used by molecular compounds? • Write the name of the first element • Add the suffix “ide” on the end of the second • Add the appropriate prefix on the element (Table 2.4) • Ex. Carbon Dioxide

  42. Naming compounds • What is the naming exception for molecular compounds? • When carbon and hydrogen are involved: • Methane (CH4) • Butane (C4H10) • Specially named substances with hydrogen: • Water (H2O) • Ammonia (NH3)

  43. Naming compounds • What are acids and how do we name them? • A substance that produces hydrogen ions when dissolved in water • Add the prefix “hydro” and the suffix “ic acid” to the non-hydrogen element

  44. Naming compounds • What are oxoacids and how do we name them? • Acids that contain hydrogen, oxygen and another element • Take the central atom and add the suffix “ic acid” • HNO3 – Nitric acid • HClO3 – Chloric acid

  45. Naming compounds

  46. Naming compounds • What are bases and how do we name them? • A substance that produces hydroxide ions (OH-) when dissolved in water • Name of the element with the word hydroxide added to the end • NaOH - Sodium Hydroxide • Ba(OH)2 – Barium Hydroxide

  47. Naming Compounds • What are hydrates and how do we name them? • Compounds that have water molecules attached to them • Name the compound and indicate the # of water molecules using the Greek prefixes and the suffix “hydrate” • Ex. Barium chloride dihydrate • BaCl2 * 2H2O • The prefix word anhydrous means that the compound has no water compounds attached

  48. Naming Practice Answers: Potassium hypochlorite Silver carbonate Nitrous acid Potassium permanganate Cesium chlorate Potassium ammonium sulfate Iron (II) oxide Iron (III) oxide Titanium (IV) chloride Sodium hydride Lithium nitride Sodium oxide Sodium peroxide