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10/16/2014 • Take our your worksheet from yesterday! • Complete your WS on determining the identity of an element before your Bell Ringer. • If you get finished, copy the Bell Ringer into your journal and answer the questions. • TEST tomorrow so look over your notes NOW. Thursday 10/16/2014 Bell Ringer: Write and complete the statements. 1. The identity of an element is determined by _______________. 2. In a neutral atom, the # of protons equals the # of ____________. 3. The # of neutrons can change. Neutrons add ________ to the atom. Thursday 10/16/2014 Bell Ringer: Write and complete the statements. 1. The identity of an element is determined by # of protons in the nucleus. A=P 2. In a neutral atom, the # of protons equals the # of electrons. A=P=E 3. The # of neutrons can change. Neutrons add mass to the atom. Elements are made of only 1 kind of atom, and the atom is identified by the # of protons in the nucleus. Mass • Mass is the amount of matter in something. • The unit of measure for atoms is amu (atomic mass unit) Atomic Mass Unit 1 atomic mass unit = 1.66053886 × 10-27 kg Kg is Kilograms Relative Mass of Subatomic Particles What is a Symbol? Elements and Chemical Symbols Chemical Symbols / Element Names Co Cobalt C Carbon Writing Chemical Symbols 1. First letter is capitalized 2. Second letter is lower case 3. NO period at the end H Cl O Hg Fe Sn C He Does it really matter? Co or CO Co Cobalt-60, extensively used as a tracer and a radiotherapeutic http://members.tripod.com/duebills/27.html Co Alloys for metals used in jet turbines CO Kills 200 People in United States http://www.cpsc.gov/cpscpub/pubs/466.html CO Produced by Incomplete Burning of Fossil Fuels CO carbon oxygen carbon monoxide Colorless Odorless Poisonous gas Think before you write a Element’s Symbol Elements are substances: •That cannot be broken down into other substances •Made of atoms with the same number of protons in the nucleus Elements are listed on the Period Table Use your copy of the Periodic Table of Element Correctly write the symbol for: 1.Carbon 2.Nitrogen 3.Oxygen 4.Iron 5.Chlorine C N O Fe Cl Atomic Number Number of Protons in every Atom of that Element What is the name of the element with the following number of protons? A.2 Helium B.6 Carbon C.8 Oxygen D.11 Sodium E.47 Silver Protons + electrical charge + Neutron No electrical charge Electrons - electrical charge - Neutral Atoms (Atoms without Electric Charge) Have equal numbers of: Protons (+ charges) Electrons (- charges) A=P=E • Atomic # = # Protons = # Electrons • Because the number of positive charges equals the number of negative charges, the atom is neutral (no charge) How many electrons? 1 proton 1 electron 9 protons 9 electrons 99 protons 99 electrons Atomic Mass The atomic mass is listed on the individual element card on the Periodic Table. Isotopes • Not all atoms of the same element have the same number of neutrons. Most Carbon atoms have 6 neutrons, although some have more and some have less. Atoms of the same element with differing numbers of neutrons are called isotopes. The number of neutrons does not change the atom or the element it makes up; it just changes the mass of the atom. Most elements have isotopes. Atomic Mass Number Protons + Neutrons To calculate # of neutrons 1. Round the Mass Number to the nearest whole number Round to 28 Atomic Mass Number Protons + Neutrons Calculate # of neutrons 2. Subtract Atomic Number From Mass Number 28 (Mass #) -14 (Atomic #) 14 Neutrons To find the AVERAGE # of Neutrons in the atom • Round the atomic mass to a whole # • Subtract the # of protons (also the atomic #) • The difference is the average # of neutrons in the nucleus. M–A=N M is the Mass # (atomic mass) A is the atomic # (# of protons) N is the # of neutrons Use the Periodic Table and Math Skills to fill in the blanks Symbol Atomic # Mass # He 2 4 3 7 N # Protons # Neutrons # Electrons 2 3 7 7 # protons is the atomic # protons + neutrons = mass # #electrons = # protons Symbol Atomic # Mass # # Protons # Neutrons # Electrons He 2 4 2 2 2 Li 3 7 3 4 3 N 7 14 7 7 7 •Part 2 Compounds 2 or More Elements Chemically Combined Hydrogen 2-H: 1-O Hydrogen Oxygen Ratio 2:1 H H O H2O 1 is not shown Formulas use element symbols with subscript numbers Water Change the ratio Change the substance Hydrogen 2:2 Peroxide H2O2 Subscript numbers http://www.wonderquest.com/images/2003-08-08-peroxide.jpg No subscripts?? 1Na NaCl Salt 1Cl How many elements? 2 Sugar C6H12O6 How many elements? 3 How many hydrogen atoms? 12 √ Check your understanding 1. The symbol for carbon is – A Ca B c C CA D C 1. The symbol for carbon is – A Ca Incorrect: Symbol for calcium B c Incorrect: st 1 letter is always a capital 1. The symbol for carbon is – C CA D C Incorrect: C is carbon There is no element with the symbol A Correct: Capital C is the symbol for carbon 2. How many protons are in an atom of sodium? A 11 B 12 C 23 D 34 2. How many protons are in an atom of sodium? A 11 Correct: atomic # is 11 B 12 Incorrect: 12 is the number of neutrons 2. How many protons are in an atom of sodium? C 23 Incorrect: 23 is the mass number D Incorrect: 34 No subatomic particle # is found by adding the atomic and mass numbers 3.How many neutrons are there, if the mass number is 1 and the atomic number is 1? A 3 B 2 C 1 D 0 3.How many neutrons are there, if the mass number is 1 and the atomic number is 1? A 3 Incorrect: There may be more or less neutrons than protons B Incorrect: 2 No subatomic particle # is found by adding the atomic and mass numbers 3.How many neutrons are there, if the mass number is 1 and the atomic number is 1? C 1 Incorrect: There is 1 proton & 1 electron D 0 Correct: 1-1 = 0 4.How many electrons are in an atom of Cl? A 17 B 18 C 35 D 0 4.How many electrons are in an atom of Cl? Correct: A 17 There are 17 + charges, so there are17 - charges B 18 Incorrect: 35-17 = number of neutrons 4.How many electrons are in an atom of Cl? C 35 Incorrect: Mass # is the sum of protons & neutrons D 0 Incorrect: All neutral atoms have at least 1 electron 5.Which of the following is a formula? A H B O C H2O D h2o 5.Which of the following is a formula? A H B Incorrect: Symbol for hydrogen O Incorrect: Symbol for oxygen 5.Which of the following is a formula? C H2O Correct: There are 2Elements The ratio is 2:1 Incorrect: D h2o 1st letter is a capital 2 is not written as a subscript 6.How many elements are in baking soda, NaHCO3 ? A 6 B 5 C 4 D 3 6.How many elements are in baking soda, NaHCO3 ? A 6 Incorrect: There are 6 atoms B Incorrect: 5 The lower case “a” is part of the symbol for sodium 6.How many elements are in baking soda,NaHCO3 ? C 4 Correct: 4 elements: sodium, hydrogen, carbon, oxygen Incorrect: D 3 3 is the subscript for oxygen Graphics Microsoft Clip Art Microsoft Office Online http://www.wonderquest.com/images/2003-08-08-peroxide.jpg http://www.cpsc.gov/cpscpub/pubs/466.html agenthttp://members.tripod.com/duebills/27.html http://www.wonderquest.com/images/2003-08-08-peroxide.jpg http://www.tea.state.tx.us/student.assessment/taks/booklets/science/g8e.pdf Isotopes • Not all atoms of the same element have the same number of neutrons. Most Carbon atoms have 6 neutrons, although some have more and some have less. Atoms of the same element with differing numbers of neutrons are called isotopes. The number of neutrons does not change the atom or the element it makes up; it just changes the mass of the atom. Most elements have isotopes. Isotopes • Not all atoms of the same element have the same number of neutrons. Most Carbon atoms have 6 neutrons, although some have more and some have less. Atoms of the same element with differing numbers of neutrons are called isotopes. The number of neutrons does not change the atom or the element it makes up; it just changes the mass of the atom. Most elements have isotopes.