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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 3. Hydrogen 2. Dirt 4. Salt Water 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. Catalyst Videos about atoms! Introduction to Atomic Structure White Board Practice: Atom “I Spy” Edible Atoms Lab Exit Slip http://www.youtube.com/watch?v=bw5TE 5o7JtE&feature=related http://www.youtube.com/watch?v=zGMwSKFBpo http://scaleofuniverse.com/ …but first, a short history lesson and the story of Mr. Rutherford, who had a little too much time… 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) Atoms Explain Gas Properties Proposes atomic theory based on three scientific laws about the properties of matter. Lead block Uranium Flourescent Screen Gold Foil What he expected What he observed Assumptions: Atom is mostly empty. Small dense, positive piece at center. Rays deflected by center. + + Two regions: Nucleus- dense center Electron cloud- empty space where you might find an electron 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. Charge: Positive Location: Nucleus Mass: 1 atomic mass unit Charge: no charge Location: nucleus Mass: 1 atomic mass unit Charge: Negative Location: electron clouds (orbitals) Mass: 0.00005 amu (so small don’t even worry about it) Name Location Electron (e-) Orbitals -1 Mass (in amu = atomic mass unit) Negligible Proton (p+) Nucleus +1 1 Neutron (no) 0 1 Nucleus Charge What did the cashier say to the neutron as it reached for its wallet? …You’re free of charge! 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 APEMAN Atomic number = Proton number and Electron number. Mass number – Atomic number = Neutron number. IODINE: ~127 AMU TELLURIUM: ~127 AMU 6.24 g/cm3 Density Melting Point 449.51 °C Boiling Point 988 °C Density4.93 g/cm3 Melting point 114 °C Boiling point 184 °C One proton 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!) “I spy an element with an atomic number of… 25.” 109.” 72.” 87.” 1.” 6.” 98.” 74.” “I spy an element with an atomic mass of… 83.798.” 226.” 40.078.” 4.00.” 9.01.” 39.098.” 261.” 55.845.” 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? Sometimes, atoms of the same element have different numbers of neutrons. Atoms of the same element with different numbers of neutrons are called isotopes. Which of the following are isotopes of the same element? (A) (B) (C) (D) 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. • 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. 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 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 Catalyst Periodic Table Song Introduction to Atomic Structure Atom “I Spy” Edible Atoms Lab Review Elements Project The atomic number always appears on the lower left side of the symbol. H He 1 Li 2 3 Be B 4 5 Mass numbers are written on the upper left side of the symbol. 1 H 2 H 3 He 4 He 6 Li 7 Li 9 Be 10 B 11 B The charge on an ion is shown on the right side of the symbol. Cl- Na+ Mg2+ Al3+ F- O2- 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!