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Chemistry 11 – Early models of the atom 1 Structure of the Atom Democritus • Developed the idea of ___________ • Thought “things” were made of atoms that have different ___________ Aristotle • Matter is made of different amounts of: ___________,___________,___________, and___________ John Dalton • ompnd • JJ Thomson • Elements are made up of very ______________________ atoms. An element is made up of a group of ___________atoms. A particular combination of specific types of atoms creates ______________________. Chemical reactions involve the re-shuffling of the atoms in a compound to make new compounds. Atoms contain ___________. • ______________________________________ • atoms • . e- ______________________________________ ______________________________________ __________________. Plum pudding • “______________________” Model (Draw in the box) model e - e e ' e - - Chemistry 11 – Atomic Theory Study Guide 1 Subatomic Particles: Electrons, Protons, and Neutrons For Rutherford-Bohr Model: He neutral • • + , t electron - + 2 > U neutron pt 2 , - e ) proton A ) } # Pt nucleus ¥32 etts Atomic # = 2 = Ptt # n 4 # Definitions: Positively charged subatomic particle found in nucleus. • Proton: ______________________________________________________________________ subatomic particle found in nucleus. • Neutron:Neutral _____________________________________________________________________ • Electron:Negatively _____________________________________________________________________ charged very light subatomic particle. Mass Electron Symbol Charge Mass (amu) = = # Proton pt e- Neutron n + - 0 1 lightest but Atomic Number and Mass Number Look at K for example: Atomic Number _________________ Atomic Mass _________________ ↳ = # # Ptt # Different up most space _________________ Symbol pt # takes 19 K Potassium 39.098 _________________ Name n from Mass # # = Ptt # n Definition: Atomic Number: # of p+ in the nucleus Of an element is the _______________________________________________ of its atoms. No two elements have the _______ Same atomic number. This number defines an ________________. Element Increases by ______ as you go through the periodic table (refer to periodic table) One . • Number of protons = _________________________________ # of e- (in neutral atoms) Therefore, for K: 19 protons = ______ 19 electrons in a neutral atom. Chemistry 11 – Atomic Theory Study Guide 2 So how do we fill the electrons in the shells? • We follow the rule that certain shells can hold a certain number of electrons. 2 1st shell: ___ e8 e2nd shell: ___ 3rd shell: ___ 8 e th 4 shell: ____ 18 e …etc. We will only focus on the first 20 elements for now! Bohr Diagram for K: . . K neutral . ÷. : atomic lqpt . . i. # = 19 = # pt # e- = Ions: Energy Removed from an atom if enough ____________ • Electrons can be ______________ is applied to it. For example, • • Na atom sodium atom 11 protons 11 electrons Na+ sodium ion 11 protons 10 electrons → remove e- Full and stable outermost (valence) shell. Ions usually form as a result of atoms having _________________________________________. +ve charged ions have ______ electrons Gained Lost electrons, while –ve charged ions have __________ Leaton Bohr Diagram for Na+: . . : . llpt . . - For . l anion Nat atomic # 11 = # = # e- pt 1=10 =11 How do we find out the number of neutrons in an atom? the on not appear Integer ( Does Definition: ctable ) Mass number: p = Sum of # of p+ and n in the nucleus. __________________________________________________________________. - Can increase by more than one when going from __________________________________________________________________. one element to the next one. Chemistry 11 – Atomic Theory Study Guide • By convention, Mass number ________ Atomic number _________ = = .fr#ic # Of pttn # ↳ Example using K: 3 39 Pt - 19K Different # n = taYwa#ys5 greater mass 20 How many neutrons are present in an atom of K that has mass number = 39? mass number = number of protons + number of neutrons number of neutrons = Mass # - #p+ = 39 19 = 20 - Isotopes • Neutron (remember Not all atoms of the same element contain the same number of ___________ number of protons determines the identity of elements, NOT the number of neutrons). Definition: Isotopes: Atoms of the same element having different mass (or different # of n) _______________________________________________________________________ Example: Carbon, C has three naturally occurring isotopes: C-12, C-13, oooC-14 Mass # Summary: When #p+ is changed = form different element Electron Configuration When #e- is changed = form ion (anion or cation) When #n is changed = form isotope Definition: Electron Configuration: • _______________________________________________________________________ _______________________________________________________________________ 4 types of shells: • s orbitals can hold ___ e• p orbitals can hold ___ e• d orbitals can hold ___ e• f orbitals can hold ___ e- Chemistry 11 – Isotope Calculation Study Guide ! Isotope Calculation Complete the following table: !" !! !" !! or C-12 # of p+ 6 or C-13 !" !! 6 6 66 12 13 - # of e 6 6 12-6-6 # of n + Atomic # (# of p ) + Mass # (# p + n) 13-6=7 6 Atomic mass rltrom or C-14 14-6=8 6 14 tabTe2°0 periodic Why is the mass number of element different from the atomic mass? The mass number is a whole number which represents sum of # of p+ and n but atomic mass is usually a decimal number which represents the molar mass of the element. same as atomic Has a unit - g/mol mass Definition: Weighted average of masses of all isotopes of an element. Molar mass: ________________________________________________________________________ e.g., Molar mass of Cl is ____________. 35.591mA Where did this number come from? • Scientific data tells us that there are two isotopes of chlorine Cl-35 and Cl-37. 75.77% of the element is Cl-35 and 24.23% of it is Cl-37. fsigma !"#$%!!!"##! = ! = take sum = find total !"#$%&'(!!"!!"#$#%& !!!(!"##!#!) 75.77400-350%-1.230104037 0.7577×351+(0.2423×37)=35.4814161 =( MMC d) 35.51¥ = e.g., What is the molar mass of boron, given that there are: • 18.8% of B-10 MMCB • Rest is all B-11 188×10 )=(. )t(.812×11 ) µ 100010-18.8010 = 10.81$ = 81.2010 e.g., What is the molar mass of magnesium, given that there are: • 78.99% of Mg-24 = • 10.00% of Mg-25 MMC Mg ) • Rest is all Mg-26 ! H = (1101×26) + (7899×24)+(1000×25) -24,3M¥ = ! 10.81€ 100010-78.99010-10.0040=11.01010 24.32/0/21 Quiz Atomic Theory Quiz 1 Review includes Molar calculation mass -→ ffaxsts 1. Complete the following table to summarize properties of subatomic particles. Subatomic Location Relative mass Charge particle Nucleus proton 1836 +1 Nucleus neutron 1837 Neutral Electron cloud electron 1 -1 2. Summarize the contribution of each scientist on atomic theory Scientists Contribution John Dalton Defined how an element is made up of a same type of particles known as atoms. Compound is made up of multiple types of atoms. JJ Thomson Contributed to the discovery of electrons and developed plum pudding model. Ernest Rutherford Through gold foil experiment, discovered the presence of concentrated positive charge in the core of an atom. (Proton and nucleus) Electrons circulate around the nucleus of an atom within a specific electron shell. Niels Bohr Erwin Schrodinger Electrons are found within electron clouds but their exact location can never be known. 3. Complete the following table. The first two rows are completed as examples. Isotope Protons Neutrons Electrons Mass # Charge 6 6 6 12 Neutral 17 18 18 35 -1 86 222 Neutral 14 10 27 +3 74 54 !" !C [ !" !"Cl ] 28262 [ Efste ] 800 ] ' 22286 86 Rn [ BAD [ " '→ 27-14 = -2 ' !" !"Mo [ jEHs]⇒ Y = 13 52 136 52+1,426 8 16-8=8 10 16 42 96-42=54 42 96 108 26=5 ,Tf°g 105 265 -2 -2 Neutral +3 Atomic number = # of protons Mass # = # of p + # of n (Mass # is different from atomic mass. Atomic mass is the average mass of all isotopes.) Number of e depends on the charge of the isotope. # p = # e for neutral isotopes. # p > # e for cations. # p < # e for anions. ! Chemistry 11 – Atomic Theory Study Guide Electron Configuration Introduction Inquiry Activity Column Element - #e Row Block Number within the , letter , superscript Electron configuration block 1s22s1 Li 3 2 S 1 Be 4 2 S 2 1s22s2 N 7 2 1s22s22p3 F 9 2 p 3 P 15 3 Mn 25 Br 35 4 P 3 Y 39 P * 4 p * 5 1s22s22p5 5 d 1s22s22p63s23p3 1s22s22p63s23p64s23d5 5 1s22s22p63s23p64s23d104p5 5 d 1s22s22p63s23p64s23d104p65s24d1 1 Questions: Z superscript 1. How is the # of e- for an element related to the number found in its electron configuration? = # - e 2. How is the location of the element (row) related to the number found in its electron Row Row # s final in number 3. How is the location of the element (block) related to the number found in its electron configuration? = configuration? = Block final letter 4. How is the location of the element (column) related to the number found in its electron = final superscript 5. The numbers in front of letters represent ________________________. row configuration? Column = 6. The letters represent ________________________. block - 7. The superscripts represent ________________________. # e ← ROW -> → 1522522136352 3p6 452 552-449 → → 1 23 4 5 I 67 }d'04p6 - 8 =3 9 10 -7 → column I e- configuration