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Crazy Clue-What Element am I?. What do dogs do with their bones? Storage space for cars Half of a dime. Lone Ranger’s Horse Male member of the Ganese tribe A prison inmate that does stand up comedy. Superman’s weakness What do you do to your clothes when they are winkled?
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Crazy Clue-What Element am I? • What do dogs do with their bones? • Storage space for cars • Half of a dime. • Lone Ranger’s Horse • Male member of the Ganese tribe • A prison inmate that does stand up comedy. • Superman’s weakness • What do you do to your clothes when they are winkled? • What do you do to your clothes when they are ripped? • If someone ate all the cookies on your plate, you would cry, “They _______.”
Elements- Pure substances that are all made of the same type of atom • Represented by chemical symbol • Most are solids at Room Temp. • Earth’s crust made of 92 naturally occurring elements • Building blocks of matter
John Dalton’s RecommendedChemical Symbols Alum molecule
How symbols were determined: • 1. Use first letter of Name of element • 2. Where conflicts, First letter plus one additional letter (only capitalize first letter) • 3. Still conflicts, select symbol from Latin Name
W = wolfram (tungsten)Cu = cuprum (copper)Au = aurum (gold)Fe = ferrum (iron)Pb = plumbum (lead)Hg = hydragyrum (mercury)K = kalium (potassium)Ag = argentum (silver)Na = natrium (sodium)Sn = stannum (tin)Sb = stibium (antimony)
Atom • Smallest piece of matter that still has the properties of the element • All elements made of atoms
Atomic Structure Protons - (p+) • Positive charge • Found in nucleus • Mass of 1 amu
amu • (atomic mass unit)** Unit of measurement for atomic particles which is 1/12th the mass of a carbon atom containing 6 protons and 6 neutrons
Neutrons – (no) • No charge • Found in nucleus • Mass of 1 amu
Electrons– (e-) • Negative charge • Surround the nucleus, electron cloud • No significant mass
“Sub-Subatomic Particles”: • Quarks – smaller particles that make up protons and neutrons • Leptons – smaller particles that make up electrons
Atomic Number • The number of protons in an atom • Number of protons also identifies the element • Whole number on Periodic table • No 2 elements have the same atomic number • Atomic #10? • Neon • Atomic #9 ? • Fluorine
Number of electrons? If the atom is neutral: Positives = negatives # of protons = # of electrons Atomic # = # of electrons
How many Protons and electrons? • Carbon? • 6 protons, 6 electrons • Sodium? • 11 protons, 11 electrons • Iron? • 26 protons, 26 electrons
Mass Number • What has mass in atom? • Protons and neutrons • the sum of the number of protons and neutrons in an atom • # neutrons = Mass # - Atomic # (protons) • Is a whole number for that atom.
How many p+, n0, e-? • Lithium –7? 3 p, 4 n, 3 e • Aluminum –27? 13 p, 14 n, 13 e • 40K? 19 p, 21 n, 19 e • 80Br? 35 p, 45 n, 35 e
Isotopes • Atoms of the same element with different numbers of neutrons • Same atomic # but different mass #
3 isotopes of Hydrogen Protium Deuterium Tritium
Isotopes: • Different Isotopes have different properties • Carbon – 12 Carbon – 14 • Some are unstable/radioactive
Use for Radioactive Isotopes: • Radioactive Dating • Such as Carbon-14 dating • Tracers in Medicine I-123 (thyroid imaging) • Radiation Therapy for Cancer • Irradiation of foodCobalt-60 • Smoke Detectors Americium-241
Charged atom Different number of protons and electrons No longer neutral Ions
Average atomic mass On periodic table • The weighted average mass of an element’s isotopes • Using Hydrogen • Is closest to the element’s most abundant isotope’s mass number • (if you round the number) • Ex. Lithium – 6.941 • Lithium – 7 is most abundant
Electron Energy Levels / Orbits • each of the 7 energy level can hold a maximum number of electrons
Each energy level is a different distance from the nucleus • Atoms only have the number of energy levels that are needed for its electrons • Levels closest to the nucleus have lower amounts of energy
Rules for filling energy levels (atomic # 1-18) – Think of Stadium Seating!! • 1. electrons are placed in lowest level first • 2. when level 1 is full then use level 2 • 3. fill each shell to capacity until you get to 3rd level (then these rules don’t apply)
Drawing Bohr Models Oxygen Sodium Neon
Dmitri Mendeleev Late 1800 devised the 1st periodic table • Based on elements atomic mass number • at the time only about 63 known elements • left spaces in table for elements yet to be discovered • There were some problems with his table
By arranging the elements in order of increasing atomic weight he discovered that there existed a periodicity of the elemental properties. He used this periodicity to create a table in which that elements with similar properties were vertically aligned with each other. In making such alignments Mendeleev was able to determine that several, as yet unidentified, elements should exist (the elements with masses 44, 68 and 72 are examples). He went on to make predictions about the properties of these missing elements which aided in their discovery. The discovery of scandium (44), gallium (68) and germanium (72) and examination of their properities (which were very similar to those predicted by Mendeleev) provided evidence for the validity of the periodic table.
Henry Moseley (1913) arranged elements by atomic number rather than atomic mass
Modern Table – by increasing atomic # • Vertical Columns “groups or families” • 18 groups • Have similar properties • Elements have the same number of electrons in outer energy level • Calledvalence electron #
Horizontal Rows • “periods or series” • - 7 periods • - don’t share similar properties • - all elements in the same period have the same number of electron energy levels
Electron Configurations: • 1.Within energy levels are orbitals or smaller mini orbits • “s” Spherically shaped (2 e-)
Each orbital has a certain number of sub-orbitals that can each hold up to 2 electrons (that spin opposite each other) • -Rules for filling sub-orbitals: • 1. - “s” ALWAYS fills first in any energy level • 2. - If it has a “p” then fills after the “s” • 3. If it has a “d” orbital, it is always skipped in favor of the next levels “s” • 4. -Then after “s” is filled, go back to the “d” one energy level lower
6 10 2 6 2 6 2 2
The Periodic Table Contains all the known elements