Aim : How can there be different varieties of atoms?

1. Unit: Atomic StructureEssential Questions: How did the concept of the atom change over time?What components make up an atom?How are atoms of one element different from atoms of another element?CCLS:RST 1,2,3,4,7,8,9WHST 1a,1b,1c,1d,1e, 2a,2b,2c,2d,2e, 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?

2. Properties of Subatomic Particles

3. Properties of Subatomic Particles

4. Atoms of Elements • 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

5. Atomic Number • If a atom of Argon has: • An atomic number of 18 • An atomic mass of 40 • 18 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-

6. Atomic Mass Number • If a atom of Argon has: • An atomic number of 18 • An atomic mass of 40 • 18 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+ + # n0

7. Atomic Mass Number • 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.

8. Neutral Atoms • 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

9. Atomic Number & Atomic Mass Number • 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+ + # n0

10. Atoms of the First Ten Elements

11. Atoms of the First Ten Elements

12. Disproving Dalton’s Atomic Theory • 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

13. Bohr’s Model • Describe what Bohr’s model of the atom looks like. • Protons and neutrons are in the nucleus • Electrons surround the nucleus

14. Bohr’s Model of a Sodium Atom • Sodium, Na • Atomic Mass: 23 • Atomic Number: • #p+: • #n0: • #e-: • What is its electron configuration? • What is its shorthand notation? 11 11 12 11 2-8-1 11 p+ 12 n0 2 8 1

15. Electron Configuration of Excited State • What does it mean when an atom goes into excited state? • In ground state, Na has an electron configuration of 2-8-1 • 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? • 2-7-2 • 1-8-2 • 2-8-0-1

16. Assignment • For your assigned atom: • Indicate the #protons, #electrons, and #neutrons • Write the shorthand notation for the atom • Indicate the electron configuration in ground state • Draw the Bohr’s model for this neutral atom in ground state • 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.

17. Isotopes • 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)

18. Unit: Atomic StructureEssential Questions: How did the concept of the atom change over time?What components make up an atom?How are atoms of one element different from atoms of another element?CCLS:RST 1,2,3,4,7,8,9WHST 1a,1b,1c,1d,1e, 2a,2b,2c,2d,2e, 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?

19. Magnesisum-24 • *REMINDER* The 2 equations you need are: • Atomic # = #p+ = #e- • Atomic mass = #p+ + #n0 • Atomic mass – • Atomic number – • # protons – • # neutrons – • # electrons – 24 12 12 12 12

20. Ions • 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

21. Charged Atoms – Ions • 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? 12 protons +1 +12 10 electrons ? electrons -1 -10

22. You Try! • 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?) +1 +14 14 protons 18 electrons -1 -18 -4 +1 +8 8 protons 10 electrons -1 -10 -2 This is O-2

23. Weighted Atomic Mass • According to your Periodic Table, what is the atomic mass of hydrogen? • 1.00794 amu (atomic mass units) • If the three isotopes of hydrogen have different atomic masses, where do we derive 1.00794 amu?

24. Weighted Averages • In a Chemistry class: • Which category would have the greatest effect on your overall? • How would you calculate your overall grade?

25. Weighted Averages • 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.

26. Weighted Atomic Mass • 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?

27. 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?

28. Practice • Calculate the average atomic mass for O and N.

29. Practice • Calculate the average atomic mass for O and N.