Catalyst

1. Catalyst • A quantitative observation involves numbers and measurement. A qualitative observation is descriptive. Classify these observations: • There are 550 students at OHS. • The sky is blue. • My car is old. • The door is 2.2 m tall. • Classify the following matter as either a pure substance or a mixture: 1. Gold 2. Dirt 3. Hydrogen 4. Salt Water

2. Objectives • I can draw a diagram of an atom and label the subatomic particles. • I can define atomic number and mass number and explain their relationship to subatomic particles. • I can use the periodic table to identify elements and their subatomic structure.

3. Agenda • Catalyst • Videos about atoms! • Introduction to Atomic Structure • White Board Practice: Atom “I Spy” • Edible Atoms Lab • Exit Slip

4. Introduction to the Elements • http://www.youtube.com/watch?v=bw5TE5o7JtE&feature=related • http://www.youtube.com/watch?v=zGM-wSKFBpo • http://scaleofuniverse.com/

5. …but first, a short history lesson and the story of Mr. Rutherford, who had a little too much time… Atoms and Their Structure

6. History Democritus (460 BC) • The idea of an atomic theory is more than 2000 years old. • Ancient Greece: • Democritus: Atoms are the Smallest indivisible particles • Plato & Aristotle: there is not an ultimately indivisible particle Plato (428 BC) Aristotle (384 BC)

7. 1680 - Isaac Newton & 1800’s - John Dalton Proposes atomic theory based on three scientific laws about the properties of matter. Atoms Explain Gas Properties

8. Evolution of the Atom Model

9. Flourescent Screen Lead block Uranium Gold Foil

10. What he expected

12. What he observed

13. + Assumptions: • Atom is mostly empty. • Small dense, positive piece at center. • Rays deflected by center.

14. +

15. The ATOM • Two regions: • Nucleus- dense center • Electron cloud- empty space where you might find an electron

16. Characteristics of the Nucleus • The nucleus is the dense, central portion of the atom. • The nucleus is made up of protons and neutrons. • The nucleus has all of the positive charge, nearly all of the mass, but only a very small fraction of the volume of the atom.

17. Proton (+) • Charge: Positive • Location: Nucleus • Mass: 1 atomic mass unit

18. Neutron (0) • Charge: no charge • Location: nucleus • Mass: 1 atomic mass unit

19. Electron (-) • Charge: Negative • Location: electron clouds (orbitals) • Mass: 0.00005 amu (so small don’t even worry about it)

20. Subatomic particles

21. POP QUIZ! • What did the cashier say to the neutron as it reached for its wallet? • …You’re free of charge!

22. Might wanna know this… • Number of protons determine an atom’s identity • # of protons= atomic social security number, it’s different for each element. • Mass Number = the number of protons + neutrons. • The mass in the nucleus. • When the atom is neutral (no net charge), the number of protons = number of electrons

23. Atomic Number and Mass…

24. A fun way to remember… • APEMAN • Atomic number = • Proton number and • Electron number. • Mass number – • Atomic number = • Neutron number.

25. What’s the difference? Tellurium: ~127 amu Iodine: ~127 amu Density4.93 g/cm3 Melting point 114 °C Boiling point 184 °C • Density 6.24 g/cm3 • Melting Point 449.51 °C • Boiling Point 988 °C

26. One proton

27. The NUCLEUS • Composed of protons (+) and neutrons (neutral) • Atomic number = Number of protons (always the smaller whole number!) • Mass number = Number of protons + neutrons (always the bigger number and always a decimal!)

28. “I Spy…” Elements Edition “I spy an element with an atomic number of… • 25.” • 109.” • 72.” • 87.” • 1.” • 6.” • 98.” • 74.”

29. “I Spy…” Elements Edition “I spy an element with an atomic mass of… • 83.798.” • 226.” • 40.078.” • 4.00.” • 9.01.” • 39.098.” • 261.” • 55.845.”

30. Rapid Fire! Charge of a proton? Charge of an electron? Charge of a neutron? Mass of a proton? Mass of an electron? Mass of a neutron? Location of proton? Location of neutron? Location of electron?

31. Sometimes, atoms of the same element have different numbers of neutrons. Atoms of the same element with different numbers of neutrons are called isotopes.

32. Find that isotope! • Which of the following are isotopes of the same element? • 6 protons, 6 neutrons, 6 electrons • 7 protons, 6 neutrons, 7 electrons • 6 protons, 8 neutrons, 6 electrons • 7 protons, 6 neutrons, 8 electrons • Answer: (A) and (C) – this is Carbon - 12 and Carbon - 14.

33. Sometimes, atoms of the same element have different numbers of electrons. • Atoms of the same element with different numbers of electrons are called ions. • When the number of protons and electrons is different, the atom becomes charged.

34. Name that ion! • 13 protons, 14 neutrons, 10 electrons • 1 proton and no electrons • 53 protons, 73 neutrons, 54 electrons • 16 protons, 16 neutrons, 18 electrons • 4 protons, 5 neutrons, 2 electrons

35. Positive or Negative? • Positively charged ions have more protons than electrons • Ex: Ca2+ (calcium ion) has 20 protons and 18 electrons • 20 – 18 = 2 • Negatively charged ions have more electrons than protons • Ex: Br- (bromine ion) has 35 protons and 36 electrons • 35 – 36 = -1

36. Agenda • Catalyst • Periodic Table Song • Introduction to Atomic Structure • Atom “I Spy” • Edible Atoms Lab • Review Elements Project

37. Atomic Structures are Represented by Symbols The atomic number always appears on the lower left side of the symbol. Mass numbers are written on the upper left side of the symbol. The charge on an ion is shown on the right side of the symbol. Cl- Na+ Mg2+ Al3+ F- O2-

38. Edible Atoms Lab • You will be working with the person sitting next to you. • Use your white board as a place mat. • You and your partner will receive a bag of cereal to use in this activity. • There is no extra cereal. Do not eat the cereal until you have finished the activity. • Earn Class Points by keeping the cereal on your place mat. • When you have finished all nine diagrams, raise your hand to get a stamp!