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Fundamentals of Chemistry – Notes Unit 2 – The atom Remember that:

Fundamentals of Chemistry – Notes Unit 2 – The atom Remember that: An _________________ is a substance that cannot be changed into _________________ substances under normal laboratory conditions. Definition:

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Fundamentals of Chemistry – Notes Unit 2 – The atom Remember that:

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  1. Fundamentals of Chemistry – Notes Unit 2 – The atom Remember that: An _________________ is a substance that cannot be changed into _________________ substances under normal laboratory conditions. Definition: Atom:______________________________________________________________________________ _____________________________________________________________________________________ element simpler The smallest particle of an element that retains The properties of that element

  2. Dalton’s Atomic Theory: 1) All ______________________ are composed of tiny _________________ particles called atoms. (We now know that atoms are actually ___________________.) 2) Atoms of the same element are ____________________. 3) Atoms of different chemicals can physically _______________ together or ________________ combine with other atoms in a ______________________________ (Ex. H2O) to form ______________________. 4) Chemical __________________ occur when atoms are separated, ___________________ or _____________________. Atoms are _________________ changed into atoms of another _________________ as a result of a chemical reaction. elements indivisible divisible identical mix chemically Whole-number ratio compounds reactions rearranged never joined element

  3. Important Info: 1) Atoms are electrically _______________________. (Thus why you don’t shock yourself when you touch something!) 2) ____________________ ____________________ (also known as atom smashers) are used to fracture atoms into dozens of kinds of ____________________ particles. (We will be studying three primary types during this class.) 3) __________________ are negatively charged subatomic particles. 4) Since atoms are electrically neutral, the negative charge carried by an ___________________ is balanced by a positive charge carried by a ___________________. 5) The third type of subatomic particle is the ________________ which carries _____________ charge. neutral Particle accelerators subatomic Electrons electron proton neutron no

  4. Particle Symbol Relative Charge Relative Mass Actual mass (g) e- -1 Electron 1/1840 9.11x10-28 p+ +1 Proton 1 1.67x10-24 n0 neutron 1.67x10-24 0 1 6) ____________________________ and ___________________________ are found located in a small, dense __________________________. 7) Electrons are found surrounding the nucleus in a region known as the __________________________ _________________________. Nucleus Protons neutrons nucleus Electron cloud

  5. Scientist Theories Democritus Dalton Thomson Rutherford Bohr Schrodinger A Little History… Matter is composed of “atoms” which are Indivisible and indestructible Atomic theory; Law of definite Proportions; Law of multiple proportions, law of conservation of mass Discovered the electron by performing Experiments in a cathode-ray tube an atom is composed of mostly empty space and a dense nucleus that contains protons and neutrons rutherford electrons travel in orbits around The nucleus bohr model Quantum mechanical model; based on probability of finding electrons within certain regions around the nucleus of the atom scientists

  6. Atomic theorists continued Model of the atom: Model:________________________Model:________________________  Scientist:_____________________ Scientist:_____________________ Notes:________________________ Notes:________________________ ________________________________ __________________________  ______________________________________________________________  ______________________________________________________________  ______________________________________________________________ electrons electrons Positive charge nucleus Plum-pudding Nuclear Atom Thomson Rutherford Negatively charged electrons are stuck into a lump of positively charged Material like raisins in dough. Electrons surround a dense nucleus and the rest of the atom is empty space. Rutherford

  7. Atomic theorists continued Model of the atom: Model:________________________Model:________________________  Scientist:_____________________ Scientist:_____________________ Notes:________________________ Notes:________________________ ________________________________ __________________________  ______________________________________________________________  ______________________________________________________________  ______________________________________________________________ 90 % Probability of finding Electron here orbit Orbital model Quantum-Mechanical Bohr Schrodinger Electrons are arranged in orbits around the nucleus; each orbit has a fixed energy Mathematically predicts the probability of finding electrons in certain regions around The nucleus quantum mechanicsfreeman

  8. Vocabulary 1) Atomic number:________________________________________________________________ _____________________________________________________________________________________ 2) Mass number:__________________________________________________________________ _____________________________________________________________________________________ 3) Atomic mass unit:______________________________________________________________ _____________________________________________________________________________________ 4) Average Atomic mass:_________________________________________________________ _____________________________________________________________________________________ 5) Isotope:_________________________________________________________________________ _____________________________________________________________________________________ The number of protons in the nucleus of an atom of An element The total number of protons and neutrons in the Nucleus of an atom (amu) A unit of mass equal to 1/12 the mass of a Carbon-12 atom The weighted average of the masses of the isotopes of an element Atoms of the same element that have the same atomic number But different atomic masses due to a different number of neutrons ions and isotopes

  9. Ways to name an atom: Example #1: Gold-197 Name of the element followed by a number which indicates the mass number of the element. The atomic number is not given in this form! Example #2: 197 Symbol for the element with the mass number shown as a Au Superscript (on top) and the atomic number shown as a 79 subscript (on the bottom). You will need to be able to read both forms and be capable of filling out a chart like the one below (watch your headings!!!): Mass number MASS number Atomic number ***On the periodic table, the atomic number is sometimes written above The Element symbol and is ALWAYS a whole number. The average atomic Mass is sometimes written below the element symbol and usually with a Decimal.

  10. ELEMENT ATOMIC NUMBER MASS NUMBER NUMBER OF PROTONS NUMBER OF ELECTRONS NUMBER OF NEUTRONS Silver 47 61 Copper 64 29 Tin 50 69 Helium 4 2 Boron 11 6 47 108 47 29 29 35 50 119 50 2 2 2 5 5 5 REMEMBER: # of electrons = # of protons = Atomic # # of protons + # of neutrons = mass number Mass number – atomic number = # of neutrons

  11. Average atomic mass calculations: F.Y.I.: Percent Abundance: the percentage of one specific isotope of an element found in nature % abundance = amount of one particular isotope ------------------------------------ total amount of all isotopes

  12. Isotope Mass Percent Abundance potassium-39 38.964 amu 93.12 % potassium-41 40.962 amu 6.88 % 1. Calculate the average atomic mass of potassium using the following data: 38.964 x 0.9312 = 36.28 amu + 40.962 x 0.0688 = 2.82 amu ______________ 39.10 amu

  13. Isotope Mass Percent Abundance magnesium-24 23.985 amu 78.70 % magnesium-25 24.986 amu 10.13 % magnesium-26 25.983 amu 11.17 % 2. Calculate the average atomic mass of magnesium using the following data: 18.88 amu 23.985 x 0.7870 = 2.531 amu 24.986 x 0.1013 = + 2.902 amu 25.983 x 0.1117 = ______________ 24.31 amu

  14. Electron Configurations An ________________________ is a method of diagramming the location of each electron in an atom based on the amount of ______________ that each electron has. So WHAT! Why is this important? Electron configuration energy

  15. Chemical properties of atoms are related to the arrangement of electrons! Remember that electrons are found in the ___________________________ of an atom. Electrons clouds are divided into major _____________ ________________ that are denoted by what are known as the ____________ ________________ ______________ n = 1, 2, 3, 4 etc. (Remember that quantum means ___________________). An energy level of at atom is defined as the region around the nucleus of an atom where an electron is likely to be moving. Each energy level in the electron cloud of an atom is then divided up into ___________________ _________________. Where are electrons found in sublevels? ________________________atomic emissons Electron cloud energy levels principal Quantum numbers Smallest amount of energy emitted or absorbed sublevels energy Atomic orbitals

  16. There are four types of sublevels: 1. The “s” Sublevel ·       Each energy level has an s sublevel. ·       s sublevels have one orbital and can hold a maximum of two electrons. ·       s sublevels have a spherical shape 2. The “p” Sublevel ·       Each energy level after the first energy level has a p sublevel. ·       p sublevels have three orbitals and can hold a maximum of six electrons. ·       p orbitals have a dumbbell shape (hourglass).

  17. 3. The “d” Sublevel ·       Each energy level after the second energy level has a d sublevel. ·       d sublevels have five orbitals and can hold a maximum of ten electrons. ·       Four of the d orbitals have a cloverleaf shape (4-leaves) and the fifth orbital looks like a dumbbell with a doughnut. 4. The “f” Sublevel ·       Each energy level after the third energy level has an f sublevel. ·       f sublevels have seven orbitals and can hold a maximum of fourteen electrons. ·       The f orbitals have shapes similar to flowers with eight petals.

  18. So how are electron configurations written? Following these rules: Aufbau:_________________________________________________________ _______________________________________________________________ Pauli Exclusion:__________________________________________________ _______________________________________________________________ Hund’s Rule:_____________________________________________________ _______________________________________________________________ Confused yet??? Try this out: Let’s build a pyramid! (If you think your teacher is crazy at this point, you are indeed correct, but that has nothing to do with this pyramid.) Electrons enter orbitals with the lowest energy first An atomic orbital can be occupied by 2 electrons At most; the 2 electrons must be spinning in opposite directions symbols When there are multiple orbitals to fill, one electron Will enter each orbital before a second electron is added

  19. The first energy level (n=1) has only an s sublevel. The second energy level (n=2) has an s and a p sublevel. The third energy level (n=3) has an s, p and d sublevel. The fourth and fifth energy levels (n=4, n=5) have s, p, d and f sublevels. 4f 5f 3d 4d 5d 6d 2p 3p 4p 5p 6p 7p 1s 2s 3s 4s 5s 6s 7s 8s

  20. Remember that each orbital can only hold two electrons! How many electrons can each sublevel hold? s = _________________ p = _________________ d = _________________ f = _________________ 2 6 10 14

  21. Electrons would fill as follows: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s Fill each of these sublevels until the total number of electrons equals the atomic number of the atom. For example: Helium (atomic number = 2) ________________ Li (atomic number = 3) _____________________ Be (atomic number = 4) ______________________ Si (atomic number = 14) ______________________ 1s2 1s2 2s1 1s2 2s2 1s2 2s2 2p6 3s2 3p2

  22. Lewis Dot Structures  Lewis Dot Structures are used to symbolically represent the electrons in the highest occupied __________ ___________ of an ___________ of an element. These electrons are known as _______________ _____________. Lewis Dot Structures are written as follows: 1)Write the element symbol: (Example: Fluorine) energy level atom valence electrons F

  23. 2) Determine the number of electrons in the outermost energy level (s and p orbitals both if applicable).   Fluorine: Atomic Number = Electrons in outer most energy level = Total number of valence electrons = 9 = 1s22s22p5 Energy level 2 = 2s22p5 7

  24. 1)Place the same number of dots as valence electrons in a filling order as follows: F . . . . . . . Electron #8 a) Top b) right OR: 12 o’clock 3 o’clock 6 o’clock 9 o’clock REPEAT c) Bottom d) left e) top f) right g) Bottom (Fluorine has only 7 electrons, electron #8 would fill To the left) H) left

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