To remain valid, models and theories must:

Note Taking Guide: Episode 301 Model: A idea used to explain facts in. Theory: An of facts and. To remain valid, models and theories must: all known enable to make correct Democritus: proposed the of an word comes from the word which means or indivisible Aristotle the of the said could be Dalton s theory proposed that atoms: are of are of the are of are in, ratios to form J.J. Thomson credited with of : a blow to atom proposed the model of the : charged embedded in a ball of 3.1

Rutherford s Gold-foil Experiment: aimed at passed a particles were particles even Conclusions of Rutherford's experiment: of the is charged The Chemistry Quiz CR1. CR2. 1. 2. 3. 4. 5. 3.2

Worksheet: Development of Atomic Theory True-False: place a "+" in the blank if the statement is true, and a "O" in the blank if the statement is false. 1. Dalton's atomic theory stated: a. atoms are indivisible. b. all atoms of the same element are alike. c. atoms unite in small, whole number ratios to form compounds. 2. The Greek philosopher Democritus was one of the first to suggest the existence of atoms. 3. The word "atom" means invisible. 4. A theory is an explanation of observable facts and phenomena. 5. Aristotle supported the idea of the atom. 6. From the "gold-foil" experiment it was concluded that the atom is mostly empty space. Short Answer and Fill in the Blanks: 1. What must models and theories do in order to remain valid? a. b. 2. The "gold-foil" experiment had the following results: of the alpha particles were deflected, of the alpha particles were reflected, and of the alpha particles passed through the gold foil. 3.3

Note Taking Guide: Episode 302 Nucleons- in the of Atomic Number- of in the of an Neutral atom- # of (+) = # of (-) Isotope- of an that have of. Isotopes of Hydrogen Hydrogen-1 proton and neutrons Hydrogen-2 proton and neutrons Hydrogen-3 proton and neutrons Mass Number- number of and in an. Example: Carbon-14 Neon-20 Particle Charge Mass Location Proton Neutron Electron Atomic Mass- of the of all the element s 3.4

Subatomic Particles # of protons = # of electrons = # of neutrons = - iron: Fe 26 55.8 protons electrons neutrons oxygen-17: O 8 15. 994 protons electrons neutrons 4 2 He protons electrons neutrons The Chemistry Quiz CR1. CR2. 1. 2. 3. 4. 5. 3.5

Worksheet: Atomic Structure Use your notes from the Atomic Structure program to answer the following questions. 1. The atomic number tells the number of positively charged in the nucleus of an atom. The atom is because this is also the number of charged in the atom. 2. The mass number tells the total number of and in the nucleus of an atom. These particles collectively are called since both are located in the nucleus. 3. Isotopes are atoms of the same element with different numbers of which results in different numbers. 4. Write the hyphen notation of the three isotopes of hydrogen: a. b. c. 5. Fill in the following chart (Hint: Isotopes may have different masses than the periodic table lists!): Symbol Atomic # Mass # # of protons # of electrons # of neutrons Hg 80 201 Mo 42 96 29 29 35 C 14 15 31 Pb 208 82 Na 11 13 3.6

Lab: Atoms and Eggs Datasheet Inside the nucleus of an atom are and. The of an atom is the sum of these two particles. The atomic number is equal to the number of present in the nucleus of the atom, and because the atom is neutral, the atomic number is also the number of outside the nucleus of the atom. Procedure: In this activity an egg will represent the nucleus of an atom and different colors of candy will represent the subatomic particles within the nucleus. Write the description of the candy used to represent the subatomic particles based on your teacher s instructions below: Particle Description The atoms have been numbered. In the data table, write the number of the atom, the number of each subatomic particle present, the mass number, and the nuclear symbol for the element represented by the atom as well as the hyphen notation for that atom. # of Atom # of protons # of neutrons Mass number Nuclear Symbol Hyphen Notation 3.7

Lab: Isotopes Datasheet Name Purpose: A new element has been discovered and it is your responsibility to learn the following about the element: the number of naturally occurring isotopes present in the element the percentage of each isotope present in your sample of the element the atomic mass of the element Procedure: 1. Obtain a sample of the element from your teacher and record its ID number above the chart. 2. Count the total number of atoms in your sample and record in the space labeled as such beside the blank for the ID#. 3. Separate the element into its different isotopes. Assign each isotope a letter to identify it and record this letter in the first column of the chart. 4. Count the number of atoms of each isotope and record in the second column of the chart. 5. Calculate the percentage of each isotope present in your element (# of atoms of isotope/total # of atoms in sample) and record in the last column of the chart. 6. Mass each isotope group of atoms and record in the third column under "Mass of Isotope Group. 7. Calculate the average mass of one atom of that isotope (Mass of Isotope Group/ # of atoms of that isotope) and record under "Average Mass of Isotope Group." ID # Total # of Atoms in Sample Isotope # of atoms in Isotope Group Mass of Isotope Group Average Mass of Isotope Group Percentage of Isotope Group 8. On the back of this worksheet, determine the average atomic mass of your element using this equation: Be sure to show your work! Average atomic mass = (avg. mass of isotope)(%) + (avg. mass of isotope)(%) +... (Remember that % means "per 100". In a calculation, 50% becomes 50/100 or 0.50.) 9. Give your element a name and symbol and record the information here. Remember that this is a new element so you, as a scientist, get to name this element whatever you want! Element Name: Symbol Atomic Mass 3.8

Worksheet: Isotope Problems 1. A student looked up the naturally occurring isotopes of bromine and found the following information: 50.54% of the naturally occurring isotopes of bromine have an atomic mass of 78.92 u while 49.46% of the naturally occurring isotopes of bromine have an atomic mass of 80.92 u. Calculate the average atomic mass of bromine, showing all work: 2. Using the following data, calculate the average atomic mass of magnesium (give your answer to the nearest.01 u) : Show all work! Isotope: 24 12 Mg Percent abundance: 78.70% Isotope: 25 12 Mg Percent abundance: 10.13% Isotope: 26 12 Mg Percent abundance: 11.17% 3. Using the periodic table, What is the average atomic mass of bromine? What is the average atomic mass of magnesium? How do your calculated answers in #1 and #2 compare to those on the periodic table? 3.9

Note Taking Guide: Episode 303 Bohr's Energy Levels Electrons in energy levels: to energy levels: from Ground State: in possible Excited Atom Atom has. state is. soon same amount of. seen as. Wave Description of Light Wavelength ( ): between on waves Frequency ( ): the of passing a given in a given c = c = : speed of Sample problem #1: What is the frequency of light if the wavelength is 6.0 x 10-7 m? 3.10

Sample problem #2: What is the wavelength of light if its frequency is 5.0 x 10 14 Hz? Particle Description of Light exists as called E = The Modern View of Light has a. Light may as a. Light may as a of called or. Spectroscopy lines represent as returns to. lines an. Called the of an. Orbital of where an is to be The Chemistry Quiz CR1. CR2. 1. 2. 3. 4. 5. 3.11

Worksheet: Electrons in Atoms I. Fill in the blanks with the most appropriate term: In Bohr s model of the atom, electrons are in certain levels, with the levels closest to the nucleus of energy than those farther from the nucleus. In the state of the atom, the electrons are in the lowest level possible. When an atom absorbs energy, it is said to be in the state, which is unstable. The atom will soon the same amount of energy absorbed which may be seen as visible light. In the study of, this visible light is seen as the spectrum of an element, which is also called an element s fingerprints. The modern view of light is that it has a nature. In other words, light may behave as a stream of particles called or, or light may behave as a. Modern scientists suggest that the nature of light depends on the experiment! In the wave view of light, the wave equation is often used to determine a wave s frequency or wavelength. The is the distance between corresponding points on adjacent waves while the is the number of waves passing a given point in a given time. The wave equation is: II. Use the wave equation to solve the following: 1. What is the frequency of light with a wavelength of 1.87 x 10-14 m? 2. What is the wavelength of light with a frequency of 5.6 x 10 14 Hz? III. Short Answer: 1. According to Planck s equation, E = hf, what is the relationship between the frequency and the energy of light? 2. According to the wave equation,, what is the relationship between the frequency and wavelength of light? 3.12

Note Taking Guide: Episode 304 Quantum Numbers Used to an in an n Represents energy level of # of in an = Example: What is the maximum number of electrons that can be in the main energy level? l The Describes the within an of orbital possible in = Orbital Shapes designated level 1: level 2: level 3: level 4: How many electrons can each sublevel hold? s = 1 orbital x 2 e - /orbital = e - p = 3 orbitals x 2 e - /orbital = e - d = 5 orbitals x 2 e - /orbital = e - f = 7 orbitals x 2 e - /orbital = e - 3.13

m The describes of in s The describes of in Ground State: energy arrangement of Diagonal Rule Examples hydrogen lithium nitrogen Orbital Notation Examples hydrogen nitrogen 3.14

Hund's Rule: of are each by one before any is occupied by a. Pauli Exclusion Principle: No two in the can have the of. The Chemistry Quiz CR1. CR2. 1. 2. 3. 4. 5. 3.15

Worksheet: Energy Levels, Sublevels, Orbitals Energy Level n E Sublevel (type of orbital) # of Orbitals in Sublevel # of e - in Sublevel Total # of e - in E level (2n 2 ) 1 2 3 4 3.16

Worksheet: The Diagonal Rule To determine the order in which electrons will fill orbitals in an atom, use the diagonal rule below. 1s Start at the top and when you reach the end of one arrow, return to the next, working your way down. 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 3.17

Worksheet: Electron Distributions 1. There are four types of orbitals: s : shaped like a An E level can contain only s orbital, making up the s sublevel. p : shaped like An E level can contain p orbitals, making up the p sublevel. d : shaped like double dumbbells An E level can contain d orbitals, making up the d sublevel. f : too complex to draw or describe An E level can contain f orbitals, making up the f sublevel. 2. Each orbital can hold a maximum of electrons. Since both electrons have a charge, they. What keeps them from flying apart? Each electron on its axis. One spins and the other spins. When charged particles spin, they act like tiny magnets. Since the two electrons spin in directions, one acts like the north pole of a magnet and the other acts like the south pole. This makes the electrons. 3. Since each orbital can hold electrons: The s sublevel can hold electrons. The p sublevel can hold electrons. The d sublevel can hold electrons. The f sublevel can hold electrons. We use this notation to describe an electron: main level 3p 5 # of e- in How are electrons distributed within a sublevel? According to Hund s Rule, each within a sublevel is half-filled before any is. 3.18

We draw orbital diagrams to show the distribution of electrons in a sublevel. Circles are used to represent the individual. are used to represent electrons in the orbital. The first electron in an orbital is represented by a! and the second by a!. A set of four numbers is assigned to each to describe its energy and location within the atom. The quantum numbers use the symbols,,, and. is the principle quantum number and represents the level of the electron. represents the sublevel of the electron, which depends on the type of. Pauli s Exclusion Principle states that within an atom, no two electrons can have the same set of. If two electrons have the same n, l, and m numbers, they are in the same level, the same, and the same. They must then have spins! So, the s quantum numbers must be different. Practice: Write electron distributions and do the orbital notation for the following: 1. P : 2. Ca: Only do the electron distributions for the following: 1. Co: 2. Eu: 3. Tc: 3.19

Worksheet: Electron Distributions Review I. Fill in the blanks: 1. The orbital shaped like a "dumb-bell" is the orbital, while the orbital shaped spherically is the orbital. 2. How many sublevels are present in the third main energy level? 3. What is the maximum number of orbitals in the "d" sublevel? 4. The maximum number of electrons that can occupy an orbital is, provided they have. 5. The maximum number of electrons that can occupy an energy level is represented by the formula. 6. The highly probable location of an electron within the atom is a(n). II. Write the electron configuration for the following: 1. Mg: 2. As: III. In the space below, show the orbital notation for Mg: 3.20

Review Sheet: Unit 3 I. Short Answer and Fill in the Blanks: 1. are a familiar idea used to explain unfamiliar facts observed in nature while a is an explanation of observable facts and phenomena. 2. To remain valid, models and theories must: a. b. 3. The existence of the atom was proposed by the Greek philosopher. The word atom comes from the Greek word atomos which means. 4. was a Greek philosopher who rejected the idea of the atom. 5. was an English schoolmaster who explained the Law of Conservation of Mass, the Law of Definite Proportions, and the Law of Multiple Proportions using an atomic theory. His theory proposed that atoms: a. b. c. d. e. 6. The discovery of the atom s nucleus can be credited to, whose -foil experiment provided experimental detail about the atom s structure. In his experiment, Rutherford aimed particles at a piece of foil. of the particles passed through the foil, but a few were, and some even bounced back (were reflected). He concluded that most of the atom is. He also concluded that the atom has a dense, charged core we call the nucleus. 7. The particles that make up the nucleus of the atom are called and are comprised of the and in an atom. 8. Atoms are because the number of charged protons equals the number of charged electrons. 3.21

9. are atoms of an element that have different numbers of neutrons, and consequently, different atomic. 10. The of an atom is the sum of all the nucleons of an atom. 11. Rutherford s planetary model of the atom faced a major problem. Classical physics predicted that the electron, as it circled the nucleus, would energy so eventually the atom would collapse! 12. Bohr placed e - in levels, assuming that the electron won t lose energy as long as it stays in the allowed level. 13. Bohr suggested that electrons can a quantum or of energy, and then jump to a energy level. This is called the state. This is an unstable state, and the atom soon gives off the same amount of energy absorbed. Some of this energy is in the form of light. 14. The science of studying visible light through the use of a spectroscope is called. The lines identify an element and are called the element s spectrum. 15. The modern view of light is that it has a nature, behaving as both a and a stream of. It simply depends on the experiment! 16. Four are used to describe the location of an electron in an atom. They are,,, and. The principal quantum number,, represents the main level of the electron. The maximum number of electrons in this level is found using the formula:. The second quantum number,, describes the shape. 17. In the electron distribution 1s 2, the 1 represents the level, the s represents the, and the 2 represents the number of in the. 18. Rule states that orbitals of equal energy are each occupied by electron before any orbital is occupied by a electron. 19. The Exclusion Principle states that no two electrons in the atom can have the set of four. 3.22

II. Charts and Problems: Show all work if applicable. 1. Complete the following table: Hyphen Notation Nuclear Symbol Atomic Number Mass Number # of Protons # of Electrons # of Neutrons Carbon - 12 6 40 K 19 5 6 2. The relative abundance of the isotopes of oxygen are: Oxygen-16: 99.760% Oxygen-17: 0.037% Oxygen-18: 0.204% Calculate the average atomic mass of oxygen: 3. In a bright-line spectrum, the wavelength of a particular line is 6.0 x 10-7 m. What is the frequency of this color of light? 4. The maximum number of electrons in a main energy level is calculated using the formula. Therefore, the maximum number of electrons in the 5 th main energy level is: 5. How many sublevels are present in the 4 th main energy level? What are they? 6. The maximum number of electrons that can occupy an orbital is, if they have. 7. Do the electron distribution and the orbital notation for: Li: O: 3.23