Presentation on theme: "The Atom and the Periodic Table"— Presentation transcript:
1The Atom and the Periodic Table FromThe Atom and the Periodic Table
2AtomsEverything in the Universe is made of stuff (also known as matter).The building blocks are the same, whether we are looking at Stars or Starbursts.
3Atoms Matter is made up of Atoms. Atoms are the smallest particle of an element.They are so small that:1 sheet of paper = 10,000 atoms thick1 drop of water has 2 trillion atoms of oxygen and 4 trillion atoms of hydrogen.The three parts of an atom are:ProtonsNeutronsElectrons
4Atoms – Protons There are three types of particles that make up atoms The first type of particle is called the PROTON.Protons are found in the nucleus of an atom.Protons have a positive (+) charge.Protons have a mass of 1 a.m.u.
5Atoms - Neutrons Another particle is the NEUTRON. Neutrons are also found in the nucleus of an atom.Neutrons have no charge. We call this neutral.Neutrons have a mass of 1 a.m.u.Neutrons act like the glue that holds the nucleus together.
6Atoms - ElectronsElectrons are the third type of particle inside of an atom.They are very small, and exist outside of the nucleus in the electrons clouds or shells.Electrons have a negative charge (-) and have almost no mass at all.
7Subatomic = smaller than an atom Atomic StructureAtoms are made up of three subatomic particles:Live where?Have mass?What charge?ProtonsNeutronsElectronsIn nucleus1 a.m.u+In nucleus1 a.m.unoneOutside nucleusNo, negligible-
9Elements Substances made of only one type of atom Identified by atomic number (protons!!!)Can not be broken down into simpler substances
10Element Symbols Shorthand name of the element Most are based on the Latin nameEx: Gold = AuThe symbol is either:One capital letter-ex: Carbon = CTwo letters…one capitol, one lower case-ex: Krypton = Kr
11H Mg Pb Atomic Number Top Number indicates Atomic Number Atomic Number = Number of ProtonsHydrogen:Atomic Number 1 = 1 protonMagnesium:Atomic Number 12 = 12 protonsLead:Atomic Number 82 = 82 ProtonsIF YOU CHANGE THE NUMBER OF PROTONS OF AN ATOM, YOU CHANGE ITS IDENTITY!!!!!!!!1H12Mg82Pb
12H Mg Pb Atomic Mass Bottom Number indicates Atomic Mass Atomic Mass = Total Mass (Number of Protons + Number of Neutrons)Hydrogen:1 (Protons + Neutrons)Magnesium:24 (Protons + Neutrons)Lead:207 (Protons + Neutrons)If we take the Atomic Mass and subtract the Atomic Number, we can figure out the number of neutrons.Pb –(Atomic Mass)207–(Atomic Number)82=125H1Mg24Pb207
13Atomic Structure (cont.) Atomic MassAverage mass of an element, based on amount of each isotope found in natureNot a whole number because it is an averageAtomic numberNumber of protons in an elementAlso, number of electrons when it is neutral (has no charge)7N14.011
14Atomic Structure (cont.) For a lithium (Li) atom:What is the atomic number?3How many protons?3How many electrons since it is neutral?What is the atomic mass?3How many neutrons?6.941 rounded to 7Usually 4
15Atomic Structure (cont.) Practice Problem #1For a sodium atom:What is the atomic number?How many protons?How many electrons since it is neutral?What is the atomic weight?How many neutrons?11111122.99 rounded to 23Usually 12
16Atomic Structure (cont.) Practice Problem #2For a boron atom:What is the atomic number?How many protons?How many electrons since it is neutral?What is the atomic weight?How many neutrons?55510.81 rounded to 11Often 6
17Atomic Structure (cont.) HeliumAtomic Number:2Protons:Electrons:Atomic Mass:4.003Atomic Mass rounded to:4Neutrons:
18IsotopesIs an atom of a given element that has different numbers of neutrons and a different mass number.It has gained or lost neutronsExamples: Carbon—12Carbon—14Mass
20Radioisotopes Is an isotope with an unstable nucleus Examples: uranium, PlutoniumIsotopes of all elements above #83 are radioactive producing radioisotopesEx. U-238 is naturally occuringU-235 is a radioisotope
21Writing Isotope Symbols Hyphen Notation- is the element symbol with the atomic mass hyphenated.Example C-12 and C-14
22Writing Isotope Symbols continued Atomic Symbol Notation:Atomic MassChemical Symbol of ElementAtomic # =# protons
23The Periodic Table Organized by trends and patterns “periodic” means repeatingThis allows you to make predictions about the atoms’ behavior based on where they are on the table
24Periods The elements are arranged on the periodic table of elements Going horizontal across the table are the PERIODS (Left to right)Period # = # of valence shellsStarting from the left, the periods go from metals metalloids nonmetals
26Periodic Table - History Dimitry Mendeleev was a Russian (actually Siberian) scientist that lived in the late 19th Century.
27Periodic Table - History When Mendeleev arranged them by Atomic Mass, he was able to predict the properties of elements that had not yet been discovered.This is the basis of the Periodic Table that we use today.
28Periodic Table - History Now the Periodic Table that we use is arranged by Atomic Number instead of Mass.Henry Moseley reordered the Periodic Table by Atomic Number
29Groups and FamiliesThe columns on the periodic table are called groups and families.The groups are the numbers; the families are the namesThey are organized by the number of valence electrons
30Metals Lose electrons to form positive ions Ductile & Malleable What do these words mean?Good conductors of heat and electricityMOST are solid at room temperature
31Nonmetals Gain electrons to form negative ions Brittle Good insulators Found as solid, liquid, or gas at room temp
32Metalloids (semi-metals) Found directly on either side of side-step lineExcept Al (this is a metal!!!)Properties of both metals and nonmetalsLess conductive than metals, but poorer insulators than nonmetalsElectrons held more tightly than metals, but can be freed with heat
33Alkali Metals Group 1A Only one valence electron VERY reactive!!!! Hydrogen is NOT included+1 charge
34Alkaline Earth Metals Group 2A Two valence electrons Not as reactive as the alkali metalsNamed because of where they are found on Earth+2 charge
35Bottom Rows are also known as the Rare Earth Metals!!! Transition MetalsFound in the middle of the tableIn the “B Groups”Can change their number of valence electronsBottom Rows are also known as the Rare Earth Metals!!!
36Halogens Group 7A Seven valence electrons VERY reactive!!!! They react with alkali metals to form salts-1 charge
37Noble Gases Group 8A 8 valence electrons—outer energy level is full Very UNREACTIVE—what do they need to be 0 charge
40Electron CloudsThe different layers of clouds hold different numbers of electrons1st cloud = 22nd cloud = 83rd cloud = 8These cloud layers conveniently match the rows on the periodic table:1st row = 2 elements2nd row = 8 elements3rd row =8 elements…And then it gets complicated
41Electron Clouds (cont.) To draw the electron clouds:Figure out how many total electronsFill in the electrons starting with the first cloudSulfur has:16 electrons
42Electron Clouds (cont.) Practice ProblemDraw the electron clouds for an Al atomThis is WAY too much work…there must be a simpler way!
43Lewis Dot StructuresA smart man named Gilbert Newton Lewis figured out an easier way!For Lewis Dot Structures draw only the important electrons…are called the outer, or valence, electronsJust draw the outer electronsaround the atomic symbolS
44Lewis Dot Structures (cont.) Practice Problem #4Draw Lewis Dot Structures for:A Calcium atomA Chlorine atomAn Oxygen atomCaClO
45Octet RuleNoble gases are what all elements aspire to be like electronicallyThese elements have 8 electrons in highest energy level8 is GREAT
46Lewis Dot Structures (cont.) All elements want to be full of electrons:So they gain or lose electrons until they are fullThis gives the atom a chargeNegative charge if they gain electronsPositive charge if they lose electronsCharged atoms are called ions: cations if they are positive and anions if they are negative
47Atomic Number Continued Also equal to number of electrons if the atom has no chargeIf the Element has a positive chargeTake the atomic number and Subtract the charge to find # of electronsK(Atomic Number)19-(Charge)1=18 ElectronsCa?If the element has a negative chargeTake the atomic number and Add the charge to find the number of electronsCl17++1K+2Ca-1Cl
48Ions How many valence electrons in Li? Is it easier to gain or lose to become full?How many will it gain or lose?What charge will it become?1lose1+1
49Ions How many valence electrons in O? Is it easier to gain or lose to become full?How many will it gain or lose?What charge will it become?6gain2-2
50Ions Magnesium-24 +2 Sulfur-33 -2 Phosphorus-34 -3 Name Symbol Atomic #Mass #ProtonsNeutronsElectronsChargeMagnesium-24+2Sulfur-33-2Phosphorus-34-3
51Atomic Tables Rules Name Symbol Atomic Number Mass Number Comes from Periodic Table WITH Mass NumberSymbolComes from Periodic TableAtomic NumberTop Number, Same as number of ProtonsMass NumberEqual to Number of Protons + Number of Neutrons(Usually Bottom Number of Periodic Table Rounded)
52Atomic Tables Continued ProtonsEqual to Atomic Number (Top)Neutrons= Mass Number – Number of ProtonsElectronsIf No ChargeEqual to Number of ProtonsIf Has a Positive ChargeSubtract Charge from Number of ProtonsIf Has a Negative ChargeAdd Charge to Number of Protons
53Practice Problems 10 30 26 Na 23 +1 16 -2 Nitrogen-15 Neon-20 Ne 10 10 NameSymbolAtomic NumberMass NumberProtonsNeutronsElectronsCharge103026Na23+116-2Nitrogen-15Neon-20Ne10101020Iron-56Fe26562611Sodium-23111210Sulfur-32S321618158-3N77