U NIT : A TOMIC S TRUCTURE E SSENTIAL Q UESTIONS : H OW DID THE CONCEPT OF THE ATOM CHANGE OVER TIME ? W HAT COMPONENTS MAKE UP AN ATOM ? H OW ARE ATOMS OF ONE ELEMENT DIFFERENT FROM ATOMS OF ANOTHER ELEMENT ? CCLS: RST 1,2,3,4,7,8,9 WHST 1 A,1 B,1 C,1 D,1 E, 2 A,2 B,2 C,2 D,2 E, 4,5,6,7,8,9,10 Aim: How can there be different varieties of atoms? Do now: What are the subatomic particles and their respective charges?

P ROPERTIES OF S UBATOMIC P ARTICLES ParticleSymbolLocationRelative charge Relative mass (mass of proton = 1 amu) Actual mass (g) Electron Proton+1 Neutron0

P ROPERTIES OF S UBATOMIC P ARTICLES ParticleSymbolLocationRelative charge Relative mass (mass of proton = 1 amu) Actual mass (g) Electrone-e- Outside the nucleus 1/ x Protonp+p+ In the nucleus x Neutronn0n0 In the nucleus x

A TOMS OF E LEMENTS So if every atom has protons, neutrons, and electrons, what makes one element different from another? Look at your Periodic Table. What numbers are different from element to element? How might we identify an element, besides from its name and/or symbol? Atomic Number

A TOMIC N UMBER If a atom of Argon has: An atomic number of 18 An atomic mass of protons 18 electrons 22 neutrons What is the relationship between atomic number and the subatomic particles? An element’s atomic number is the number of protons and number of electrons in an atom of that element. Atomic # = # p + = # e -

A TOMIC M ASS N UMBER If a atom of Argon has: An atomic number of 18 An atomic mass of protons 18 electrons 22 neutrons What is the relationship between atomic mass and the subatomic particles? An element’s atomic mass number is the number of protons and neutrons in the nucleus of an atom of that element. Atomic mass # = # p + + # n 0

A TOMIC M ASS N UMBER If all atoms are comprised of protons, neutrons, and electrons, why aren’t electrons counted in the atomic mass? The relative mass of an electron is so small that its mass is considered negligible. ParticleSymbolLocationRelative charge Relative mass (mass of proton = 1 amu) Actual mass (g) Electrone-e- Outside the nucleus1/ x Protonp+p+ In the nucleus x Neutronn0n0 In the nucleus x

N EUTRAL A TOMS All atoms are neutral!! If an atom of Argon has an atomic number of 18 How many protons does it have? 18 protons What is the charge of each proton? +1 What particle has the opposite charge? Electrons, -1 How many electrons are needed to make this atom neutral? 18 electrons

A TOMIC N UMBER & A TOMIC M ASS N UMBER Elements are identified by their atomic number. An element’s atomic number is the number of protons and electrons in an atom of that element. Atomic # = # p + = # e - Elements are different because they contain different numbers of protons. An element’s atomic mass number is the number of protons and neutrons in the nucleus of an atom of that element. Atomic mass # = # p + + # n 0

A TOMS OF THE F IRST T EN E LEMENTS NameSymbolAtomic number ProtonsNeutronsMass number Electrons HydrogenH11011 Helium4 Lithium7 Beryllium9 Boron11 Carbon12 Nitrogen14 Oxygen16 Fluorine19 Neon20

A TOMS OF THE F IRST T EN E LEMENTS NameSymbolAtomic number ProtonsNeutronsMass number Electrons HydrogenH11011 HeliumHe22242 LithiumLi33473 BerylliumBe44594 BoronB CarbonC NitrogenN OxygenO FluorineF NeonNe

D ISPROVING D ALTON ’ S A TOMIC T HEORY How do our calculations help disprove Dalton’s atomic theory? The atom is not the smallest particle; there are subatomic particles Atoms of different elements may have similarities Boron and Carbon can have the same number of neutrons Fluorine and Neon can have the same number of neutrons

B OHR ’ S M ODEL Describe what Bohr’s model of the atom looks like. Protons and neutrons are in the nucleus Electrons surround the nucleus

B OHR ’ S M ODEL OF A S ODIUM A TOM Sodium, Na Atomic Mass: 23 Atomic Number: #p + : #n 0 : #e - : What is its electron configuration? What is its shorthand notation? 11 p + 12 n

E LECTRON C ONFIGURATION OF E XCITED S TATE What does it mean when an atom goes into excited state? In ground state, Na has an electron configuration of During excited state, any one electron can move to a higher energy level as long as there is room. The total number of electrons remains the same. What are some possible electron configurations for an atom of Na in its excited state?

A SSIGNMENT For your assigned atom: 1. Indicate the #protons, #electrons, and #neutrons 2. Write the shorthand notation for the atom 3. Indicate the electron configuration in ground state 4. Draw the Bohr’s model for this neutral atom in ground state 5. Indicate one possible electron configuration for excited state Find the person(s) with the same element. On a piece of looseleaf, attach your drawings & create a t-chart of similarities and differences.

I SOTOPES What you and your partner(s) have are called isotopes. Based on your comparison, define isotopes. Isotopes are atoms of the same element that have different mass numbers. Same number of protons (because they are the same element) Different number of neutrons (remember that atomic mass = # protons + # neutrons)

U NIT : A TOMIC S TRUCTURE E SSENTIAL Q UESTIONS : H OW DID THE CONCEPT OF THE ATOM CHANGE OVER TIME ? W HAT COMPONENTS MAKE UP AN ATOM ? H OW ARE ATOMS OF ONE ELEMENT DIFFERENT FROM ATOMS OF ANOTHER ELEMENT ? CCLS: RST 1,2,3,4,7,8,9 WHST 1 A,1 B,1 C,1 D,1 E, 2 A,2 B,2 C,2 D,2 E, 4,5,6,7,8,9,10 Aim: Why are the atomic masses on the Periodic Table different from the isotope masses? Do now: How many protons, neutrons, and electrons are in Magnesium-24?

M AGNESISUM -24 *REMINDER* The 2 equations you need are: Atomic # = #p + = #e - Atomic mass = #p + + #n 0 Atomic mass – Atomic number – # protons – # neutrons – # electrons – 12 24

I ONS Ions are electrically charged atoms They become electrically charged because they have gained or lost electrons Magnesium ion, Mg +2 Look for it on your Periodic Table. What is another name for the ionic charge? The atom is no longer neutral. Let’s calculate the number of protons and electrons… That’s the charge! Oxidation State

C HARGED A TOMS – I ONS If an ion of Magnesium has a charge of +2… How many protons does it have? What is the charge of each proton? What particle has the opposite charge? How many electrons are needed to make this atom have a +2 charge? # ParticlesChargeNet Charge TOTAL =+2 12 protons+1+12 ? electrons-1010 electrons

Y OU T RY ! How many protons & electrons are in Si -4 ? What is the net charge of an ion with 8 protons and 10 electrons? (What element is this?) # ParticlesChargeNet Charge TOTAL = protons electrons # ParticlesChargeNet Charge TOTAL = -2 8 protons electrons This is O -2

W EIGHTED A TOMIC M ASS According to your Periodic Table, what is the atomic mass of hydrogen? amu (atomic mass units) If the three isotopes of hydrogen have different atomic masses, where do we derive amu?

W EIGHTED A VERAGES In a Chemistry class: Which category would have the greatest effect on your overall? How would you calculate your overall grade? Your Chemistry Class Weight and Grade % WeightCategoryYour Average 60%Exams85 20%Homework94 20%Lab78

W EIGHTED A VERAGES Because 60% of your grade is comprised of your exam scores, the 85% you received in that category affects your grade the most. Your overall grade is closest to the score you received in the exam category. Your Chemistry Class Weight and Grade % WeightCategoryYour AverageWeighted Average 60%Exams x 85 = 51 20%Homework x 94 = %Lab x 78 = 15.6 Overall Weighted Average (Overall Grade) = = 85.4%

W EIGHTED A TOMIC M ASS Atomic masses are calculated in the same fashion. Which isotope has the highest percent abundance? What mass number will the weighted atomic mass be closest to? Isotopes of Hydrogen Natural percent abundance IsotopeMass (amu) Weighted Average %Hydrogen % abundance x isotope mass 0.015%Hydrogen % abundance x isotope mass NegligibleHydrogen % abundance x isotope mass

CHECK YOURSELF  Is the calculated weighted average atomic mass close to what we see on the Periodic Table?  Is the calculated weighted average atomic mass closest to the isotope with highest percent abundance? Isotopes of Hydrogen Natural percent abundance IsotopeMass (amu) Weighted Average %Hydrogen x = %Hydrogen x = NegligibleHydrogen Overall Weighted Average = = amu

P RACTICE Calculate the average atomic mass for O and N. Isotopes of Oxygen Natural % abundance IsotopeMass (amu) Weighted Average %Oxygen %Oxygen %Oxygen Isotopes of Nitrogen Natural % abundance IsotopeMass (amu) Weighted Average 99.63%Nitrogen %Nitrogen

P RACTICE Calculate the average atomic mass for O and N. Isotopes of Oxygen Natural % abundance IsotopeMass (amu) Weighted Average %Oxygen x = %Oxygen x = %Oxygen x = Average Atomic Mass = = amu Isotopes of Nitrogen Natural % abundance IsotopeMass (amu) Weighted Average 99.63%Nitrogen x = %Nitrogen x = Average Atomic Mass = = amu