Presentation on theme: "Elements! Elements! Elements!"— Presentation transcript:
1Elements! Elements! Elements! The AtomElements! Elements! Elements!
2ObjectivesAtomic StructureThe Atomic Theory and HistoryAtomic Math
3Element QuizzesIn order to strengthen your familiarity with elements, you will be required to take element quizzes.
4Element Wanted PosterTo demonstrate you knowledge of the concepts we will cover this six weeks. You will be expected to create a poster containing information about an element in the form of a WANTED poster.
6Atomic Structure Atoms are the building blocks of matter. Atoms make up elements – in fact everything is made of atoms!There are 92 elements that occur naturally on Earth and about a dozen more that are man-made.All the elements can be found on the Periodic Table of the Elements.Atoms are mostly empty space.
7There are two regions in the atom: NucleusMost of the massHas a positive chargeElectron CloudMost of volume/spaceHas a negative charge
8Each region has specific subatomic particles NucleusProtons p+Have a positive chargeMass = 1 amuDiscovered by E. RutherfordNeutrons n0Have a neutral or no chargeDiscovered by J. ChadwickElectron CloudElectrons e-Have a negative chargeMass = 0 amuDiscovered by J.J. Thomson
9Let’s Check for Understanding What are the two regions of the atom?Which one is most of the mass of the atom?Which one is most of the volume?What are the subatomic particles and where are they found?
11Democritus and “atomos” Democritus was an ancient Greek philosopher (he lived around 400 B.C.) who believed that matter could not be divided into smaller and smaller pieces forever and ever. He called the smallest pieces of matter “atomos” which means “indivisible” or “unbreakable.”
12John DaltonA nineteenth century scientist who also believed that matter was made up of atoms. He coined the term “atom” from the Greek word “atomos.”.
13In this first modern atomic theory he stated: 1. Atoms are small, indivisible particles that are the building blocks of matter. (He viewed them as solid spheres.)2. Atoms can be physically mixed together to form mixtures.3. Atoms cannot be changed into another element through chemical reactions.
14In this first modern atomic theory he stated: 4. Atoms can be combined or rearranged in whole number ratios to form compounds through chemical reactions.5. All atoms of a particular element are exactly the same; atoms of different elements are different
15Check for Understanding What did Democritus believe?Who expanded on Democritus’ beliefs and how?Name the points of the Modern Atomic Theory.
17The Periodic Table of Elements Let’s ReviewFrom previous slides you have learned that all elements/atoms are listed on what?The Periodic Table of Elements
18H 1.008 Hydrogen 1 Atomic Number Element Symbol Atomic Mass Element Name
19H 1.008 Hydrogen 1 Atomic Number The whole number on the chart Equivalent to the number of protons and electrons if there is no charge.
20Atomic MassThe decimal number on the chart.Average number of different masses of naturally occurring isotopes of an element.Units: may be in grams or atomic mass units (amu)amu = defined as exactly 1/12th the mass of a carbon-12 atom1H1.008Hydrogen
211H1.008HydrogenMass NumberThe atomic mass rounded to the nearest whole number.Equivalent to the number of protons plus the number of neutrons.
22Atomic Math Overview # of p+ = Atomic Number # of n = Mass Number - # of p0# of e- (no charge) = # of p+
23X Elemental Symbols A Z A- Mass Number Z- Atomic Number X- Element SymbolXZ
24Fe Try this one on your own 56 26 Element Protons Neutrons Iron ElectronsAtomic #Mass #Charge56Fe263026262656
25How many protons and neutrons are in one atom of 37Li? How many protons and neutrons are in one atom of 74184W?3 protons and 4 neutrons74 protons and 110 neutrons
27IsotopesAtoms that have the same number of protons and electrons but different numbers of neutronsIsotopes have different mass numbers because of the differing numbers of neutrons
28Isotope names are the atom name and mass number hyphenated Isotopes with practical uses:carbon-14 ~ archaeological carbon datingamericium-241 ~ smoke alarmscobalt-60 ~ treatment of cancer
29IsotopesIn nature, most elements occurs as a mixture of two or more isotopes.Each isotope of an element has a fixed mass and a natural percent abundance.Example: Carbon has two isotopes. Both have 6 protonscarbon-12: six neutrons (C-12)carbon-13: seven neutrons (C-13)
30Isotopes & Atomic MassAtomic mass of an element is a weighted average of the masses of its isotopes.You can calculate atomic mass based on relative abundance. You will need the :mass of each isotopenatural percent abundance of each isotope
31Calculating Atomic Mass To calculate the atomic mass of an element:Multiply the atomic mass of each isotope by its abundance expressed as a decimalAdd the results for all isotopes
32ExampleMagnesium occurs in nature in three isotopic forms: atomic massMg-24 (78.70% abundance) amuMg-25 (10.13% abundance) amuMg-26 (11.17% abundance) amuCalculate the atomic mass of magnesium for these data.
33Calculation: For Mg-24: 23.985 amu x 0.7870 = 18.88 amu atomic mass = amu
35Ions Atoms are electrically neutral: # protons (+) = # electrons (-) Atoms may lose or gain electrons when they react with atoms of other substances. They become electrically charged particles called ions.
36Two Types of Ions Cations Anions Loss of electrons Now has more protons than electronsAnionsGain of electronsNow has more electrons than protons*Denoted by charge in upper right of symbol.
37X Atomic Math A Y Z A- Mass Number Z- Atomic Number Y- Charge X- Element SymbolAYXZ
38Denoting Ion Charges Ion charges – the sign follows after the number To calculate ion charges: # protons - #electronsExample: An atom of lithium loses 2 electrons (lithium normally has 3 e-). It now is an ion with 2 more protons than electrons. (Ion charge: 3 protons – 1 electron = 2+) Overall, this lithium ion has a positive 2 charge. Write this using the elemental symbol:Li2+We can now add the atomic number and mass number to the symbol:73Li2+
39Atomic Math Breakdown # of p+ = Atomic Number Cheat Chart# of p+ = Atomic Number# of n = Mass Number - # of p# of e- (no charge) = # of p+# of e- (w/ charge) = # of p+ - charge
40Fe Atomic Math 56 3+ 26 Element Protons Neutrons Iron Electrons Mass #Charge563+Fe263026232656+3
42Fe Try this one on your own 56 2+ 26 Element Protons Neutrons Iron ElectronsAtomic #Mass #Charge562+Fe263026242656+2
43How many protons, neutrons, and electrons are in one atom of 37Li1+? How many protons, neutrons, and electrons are in one atom of 74184W3+?3 protons 4 neutrons 2 electrons74 protons 110 neutrons 71 electrons
44Make up your own problem for each format used. Then give it to your neighbor or Ms. Adams to try