Basic Chemistry Unit 3 Hobbs 1. Bell Ringer: Thursday, Because of the Doppler Effect, when the source of the sound is coming toward you, you will hear a.the sound gets quieter b.a decrease in pitch c.an increase in pitch d.no change in sound 2. Bell Ringer: Friday, Name the energy transformations within this system. Weekly Review 3 DUE TODAY 3. Bell Ringer: Monday, What are three things you find in an element square? a.atomic number, mass number, chemical symbol b.mass number, chemical symbol, weighted average c.atomic number, chemical symbol, isotope d.avogadros number, symbol, mass number THIS THURSDAY IS ZOMBIE DAY!!! 4. Bell Ringer: Tuesday, Cobalt- # of protons # of neutrons 3033 # of electrons TOMORROW IS ZOMBIE DAY!!! 5. Bell Ringer: Wednesday, What determines the identity of the element? A. protons B. neutrons C. electrons D. quarks TOMORROW IS ZOMBIE DAY!!! MIDTERM Scantron Hints Calculator Pencil Scratch Paper Turn into MY desk once you are done!!! STUDY FOR OTHER MIDTERMS once you are done!! NO TALKING UNTIL EVERYONE IS DONE!! 6. Bell Ringer: Thursday, Phosphorous-31 # of protons # of neutrons # of electrons 7. Bell Ringer: Friday, Draw the Bohr Model for Aluminum. 8. Bell Ringer: Monday, Which is the smallest piece of matter that still retains the property of the element? A. atom B. quark C. neutron D. proton Thursday is CAMO DAY! Complete the following Bohr Modelsby yourself no talking Be Al-28 Mg 2+ 9. Bell Ringer: Tuesday, A chemical symbol represents the ____ of an element. A. Element nameC. Group B. ReactionD. Structure Thursday is CAMO DAY! Bohr Model Check Draw the following N Ca 2+ S-34 10. Bell Ringer: Wednesday, Mg +2 -what is the element? -# of protons -# of neutrons -#of electrons TOMORROW is CAMO DAY! SPS 1 Quiz Today Coloring Periodic Table Change gray light blue Change pink purple Change purple brown (transition metals) 12. Bell Ringer: Tuesday, An atom that has lost or gained electrons is a(n) a. isotopec. ion b. noble gasd. nucleus THURSDAY is TIE DAY 11. Bell Ringer: Thursday, How many electrons are needed in the outer energy levels of most atoms for the atom to be chemically stable? a. 2b. 4 c. 6d. 8 11.Bell Ringer: Name one of the families on The Periodic Table. 12. Bell Ringer: Wednesday, Hydrogen is grouped with the alkali metals because it ____. a.is a gas b.is a metal c.is a solid d.has 1 valence electron THURSDAY is TIE DAY 12. Bell Ringer: Tuesday, What type of radiation has no mass or charge and is an energetic form of light? A. alphaB. beta C. gammaD. nuclear 14. Bell Ringer: Thursday, Thorium-234 has a half-life of 24 days. If you started with a 100-g sample of thorium-234, how much would remain after 48 days? Pick an element from or the back page of the book and create an element square for that element with all of its correct information. Agenda: Finish U2 test (MC and WP) Launch U3/Pre-Test Unit 3 Notes Practice Elements Vocabulary Atoms: Smallest particle of an element that has all the properties of matter: Protons- particles in the nucleus with positive charge Electrons- particles orbiting around nucleus with negative charge Neutrons- particles in the nucleus with no charge Elements: Simplest form of a pure substance Compounds: Two or more elements chemically combined to form a new substance Sub-Atomic Particles Part of AtomChargeLocationMass/Size Electron- negativeoutside nucleus.0006 amu (too little to count) Proton+ positiveinside nucleus 1 amu Neutronno chargeinside nucleus 1 amu Cobalt- # of protons # of neutrons 3033 # of electrons Argon-42Argon-46 # of protons 18 # of neutrons # of electrons # of protons 19 # of neutrons 4244 # of electrons Radon- 224 Radon- 230 # of protons 86 # of neutrons # of electrons Ions Ion - an atom that has lost or gained electrons Two types of IONS Cation An atom or a molecule which is positively charged, so it has more number of protons than electrons. Anion - An atom or a molecule which is negatively charged, so it has more number of electrons than protons. An atom that has a charge is an ION Ions (extended sub-atomic particles) Cation An atom or a molecule which is positively charged, i.e. has more number of protons than electrons. Anion - An atom or a molecule which is negatively charged, i.e. has more number of electrons than protons. Periodic Table Using the Periodic Table Atomic Number Equal to # protons = # electrons Periodic Table is arranged by this number Symbol Shorthand for the element Note 2 nd letter is always lowercase Atomic Mass Number Total AVERAGE mass of Protons + Neutrons + Electrons 17 Cl 35.5 Atomic Mass Fractions? Look at Chlorine (atomic number 17) Atomic mass of 35.5? I dont get it! Where does the 35.5 come from? 0.5 protons? 0.5 neutrons? No Atomic Mass = average number of protons and neutrons in nature Bohr Models 1.Bohr models are used to predict reactivity in elements. 2.Reactivity refers to how likely an element is to form a compound with another element. 3.When looking at Bohr models, we look at its valence electrons (the electrons on the last energy level) to determine reactivity. Bohr Models 1.Draw the nucleus. 2.Write the number of neutrons and the number of protons in the nucleus. 3.Draw the first energy level. 4.Draw the electrons in the energy levels according to the guidelines. Make sure you draw the electrons in pairs. 5.Keep track of how many electrons are put in each level and the number of electrons left to use. Isotopes An isotope is a variation of an element (same protons) but can have diff. # of neutrons An isotope is a variation of an element (same protons) but can have diff. # of neutrons Isotopes are identified by their mass numbers Isotopes are identified by their mass numbers Written with element name and mass number OR chemical symbol and mass number Written with element name and mass number OR chemical symbol and mass number Ex: carbon (atomic mass = ) Ex: carbon (atomic mass = ) Carbon (14) and carbon (12) exist in nature Isotopes Reading Essentials Books if finished with both practice sheets! Pages Respond to all questions under headings and the AFTER YOU READ DO NOT CREATE FOLDABLE! Guided Practice In order to draw Bohr models of these elements, you must first determine the number of protons, neutrons, and electrons. Once you have found this information, follow the directions to draw your model. 6 C Carbon Protons: ____Neutrons: _____Electrons: ______ How many energy shells will this have? ____ How many valence (outer) electrons does this element have? ____ Bohr Model: Valence Electrons Electron Energy Levels Electrons are arranged in Shells around nucleus in predictable locations Fill seats closest to nucleus first (concert best seats) Seats available Shell #12 electrons Shell #28 electrons Shell #38 electrons Shell #4 18 electrons Shell #5 32 electrons Shell #650 electrons Ex. Carbon has 6 total electrons so Two electrons on first energy level Four electrons on second energy level Question: Could we fit more electrons on the second energy level if there were more electrons in carbon? Ions An atom usually has a neutral charge. That means it has the same number of protons as electrons Remember, a proton has a positive charge and an electron has a negative charge ION an atom that has lost or gained one or more electrons and has become charged either positively or negatively Ions - Cations When an atom LOSES electrons, it becomes more POSITIVE Why? If you are getting rid of negative particles (electrons) but your number of positive particles (protons) are staying the same. In other words, you are subtracting negative numbers Ions-Cations What would the charge be if: The neutral form of Gold (Au) lost 4 of its 79 electrons. It now has 79 protons and 75 electrons The neutral form of Mg lost 2 of its 12 electrons. It now has 12 protons and 10 electrons. Ions-Anions When an atom GAINS electrons it becomes more NEGATIVE Why? Electrons have a negative charge, so the more you have, the more negative you become Ions Ions are represented by placing a superscript charge number next to the atomic symbol. Ex. O -2 = oxygen with a negative 2 charge K + = potassium with a positive 1 charge N -3 = nitrogen with a negative 3 charge And so on Ions Mg +2 Ions Ca +2 Ions K +1 Ions Cl -1 Atomic Structure 17 Cl 35.5 Total Mass of Nucleus = 18 neutrons Element Name Chlorine Total # of protons and electrons (in a neutral atom) 17 protons in nucleus 17 electrons orbiting nucleus Notice: electrons follow energy level rules (Round Atomic Mass) Valence Electrons An electron on the outermost energy shell of an atom Important to understand because this is a key factor in how atoms will BOND with each other Important to understand because this is a key factor in how atoms will BOND with each other Octet rule stable atom will have 8 electrons in that outer shell Octet rule stable atom will have 8 electrons in that outer shell Practice Valence # of Practice Valence # of Chlorine? Neon? Nitrogen? Oxygen? Types of Chemical Bonds Ionic- Two elements bond by transferring electrons to create ions that attract together (+ is attracted to - after an electron is transferred) Covalent- Two elements bond by sharing electrons (strongest bond type) Metallic- Two metals bond and form a common electron cloud. This is a cluster of shared electrons (weakest bond type) Polarity Some electrons are not shared evenly in covalent bonds. One end, or pole, of the molecule has a partial negative charge while the opposite pole has a partial positive charge. Poles attract opposite charges polar substances dissolve in water Nonpolar substances do not dissolve in water Hydrogen Bonds Hydrogen bonded to O, N, or F has a partial positive charge. These hydrogens attract the negative pole of nearby molecules. This forms a hydrogen bond. Trends Use the paper as your instructions Use Chapter 19 as a guide for placement of where and how many The Periodic Table The periodic table organizes the elements in a particular way. A great deal of information about an element can be gathered from its position in the periodic table. For example, you can predict with reasonable good accuracy the physical and chemical properties of the element. You can also predict what other elements a particular element will react with chemically. The Periodic Table Properties of Metals Metals are good conductors of heat and electricity. Metals are shiny Metals are ductile (can be stretched into thin wires). Metals are malleable (can be pounded into thin sheets). A chemical property of metal is its reaction with water which results in corrosion. Properties of Non-Metals Non-metals are poor conductors of heat and electricity. Non-metals are not ductile or malleable. Solid non-metals are brittle and break easily. They are dull. Many non-metals are gases. Properties of Metalloids Metalloids (metal-like) have properties of both metals and non-metals. They are solids that can be shiny or dull. They conduct heat and electricity better than non-metals but not as well as metals. They are ductile and malleable. FamiliesPeriods Columns of elements are called groups or families Elements in each family have similar but not identical properties. For example, sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals. All elements in a family have the same number of valence electrons. Each horizontal row of elements is called a period. The elements in a period are not alike in properties. In fact, the properties, change greatly across any given row. The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas. Valence Electrons Valence electrons are the electrons in the outer energy level of an atom. These are the electrons that are transferred or shared when atoms bond together. All elements in a family have the same number of valence electrons. Alkali Metals Atoms of the alkali metals have single electron in their outermost level, in other words, 1 valence electron. They are shiny, have the consistency of clay, and are easily cut with a knife. They are the most reactive metals. They react violently with water. Alkali metals are never found as free elements in nature. They are always bonded with another element. Alkaline Earth Metals They are never found uncombined in nature They have two valence electrons Alkaline earth metals include magnesium and calcium, among others. Halogen Family Halogens have 7 valence electrons, which explains why they are the most active non-metals. They are never found free in nature. They are diatomic. They react with alkali metals to form salts. Noble Gases Noble Gases are colorless gases that are extremely un-reactive. One important property of the noble gases is their inactivity. They are inactive because their outermost energy level is full. Because they do not readily combine with other elements to form compounds, the noble gases are called inert. Atomic Radius Radius is the distance from the center of the nucleus to the edge of the electron cloud. Moving down a group, ATOMIC RADIUS INCREASES Moving left to right across the periodic table ATOMIC RADIUS DECREASES Each atom has another energy level, so the atoms get bigger. Since electrons are being added to distant shells away from the nucleus the valence electrons are SHIELED by the inner shell electrons. Reactivity What makes an element reactive? An incomplete valence electron level. All atoms (except hydrogen) want to have 8 electrons in their very outermost energy level. (This is called the octet rule). Atoms bond until this level is complete. Atoms with few valence electrons lose them during bonding forming cations (overall positive charge) Atoms with 6, 7, or 8 valence electrons gain electrons during bonding forming anions (overall negative charge) Reactivity We will be describing elements according to their reactivity. Elements that are reactive bond easily with other elements to make compounds. The most reactive metal is Francium (Fr). The closer a metal is to Fr the more reactive it is. The most reactive nonmetal is Fluorine (F). The closer a nonmetal is to F the more reactive it is. Oxidation Number The oxidation number of an element indicates the number of electrons lost, gained, or shared as a result of chemical bonding. So we are really asking for the charge. Oxidation Number Bonds Metallic Bonds Metal and metal bonded Ionic Bonds Metal and nonmetal bonded to form a compound Metal is giving its valence electron to the nonmetal Example: NaCl Covalent Bonds Nonmetal and nonmetal bonded to form a compound The valence electrons will be shared Example: N 2 O 2 Trends: Atomic Radius Moving left to right across the periodic table ATOMIC RADIUS DECREASES More protons are being added to the nucleus, valence electrons are strongly attracted to the nucleus. Electrons are also being added, but in the same shell at about the same distance so there is not much of a shielding effect. Trends: Atomic Radius Moving down a group, ATOMIC RADIUS INCREASES Each atom has another energy level, so the atoms get bigger. Since electrons are being added to distant shells away from the nucleus the valence electrons are SHIELED by the inner shell electrons. Trends Today: First you will complete the Element Wanted Ad Project, you will sign up for elements. Then you will complete the Periodic Table Search There are clues around the room to help you complete the Periodic Table Search Each person will complete there OWN answer sheet so that doesnt mean traveling around the room to look for answers. The last and final phase of today is a Periodic Trends Assessment. All matter is made up of elements (e.g. carbon, hydrogen, etc.). The smallest part of an element is called an atom. Atom of different elements contain different numbers of protons. The Atom X A Z Mass number Atomic number Element symbol = number of protons + number of neutrons = number of protons X A Z A = number of protons + number of neutrons Z = number of protons A Z = number of neutrons Number of neutrons = Mass Number Atomic Number U U There are many types of uranium: A Z Number of protons Number of neutrons A Z Number of protons Number of neutrons Most of the isotopes which occur naturally are stable. A few naturally occurring isotopes and all of the man-made isotopes are unstable. Unstable isotopes can become stable by releasing different types of particles. This process is called radioactive decay and the elements which undergo this process are called radioisotopes/radionuclides. Radioactive decay results in the emission of either: an alpha particle ( ), a beta particle ( ), or a gamma ray( ). Radioactive Decay Radioactivity: Alpha two protons and two neutrons charge +2e can travel a few inches through air can be stopped by a sheet of paper, clothing. X A Z Y A - 4 Z He 4 2 Alpha Decay unstable atom more stable atom alpha particle Radioactivity/Transmutation Practice X A Z Y A - 4 Z He 4 2 Ra Rn He 4 2 Rn He Po He 4 2 Rn Y A Z He 4 2 Radioactivity: Beta Beta rays are made of electrons traveling at nearly the speed of light. Beta rays are negatively charged and can penetrate a centimeter of aluminum. electrons ejected from the nucleus when neutrons decay Beta particles have the same charge and mass as "normal" electrons. Can be stopped by aluminum foil or a block of wood. X A Z Y A Z b 0 Beta Decay Po Rn b 0 Radioactivity Gamma rays are the most powerful of the three. The gamma rays have no mass and no charge they are a true ray or wave. Gamma rays are electro-magnetic waves and are similar to X-rays. Gamma rays are not made of any particles, they are pure energy and that is why they can penetrate more matter than other types of radiations. Some gamma rays can penetrate up to a meter of concrete. Radioactivity: Gamma Gamma radiation electromagnetic energy that is released. Gamma rays are electromagnetic waves. They have no mass. Gamma radiation has no charge. Most Penetrating, can be stopped by 1m thick concrete or a several cm thick sheet of lead. Radiation Based on the fact that high-energy gamma rays cause damage to biological molecules Tumor cells are more susceptible than normal cells Example: cobalt-60 Gamma radiation can cure cancer, but can also cause cancer Chapter 17 Review Page Write question and YOUR answer!!! Ticket Out the Door Explain the differences between alpha, beta, and gamma decay. If there were a radiation leak in the room, how would you shield yourself (what would you use as protection?) Half Life Half-life time required for half of the original sample of radioactive nuclides to decay