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Atoms, Molecules and Ions

Atoms, Molecules and Ions. Chapter 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. Atomic Structure.

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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

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