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Science AHSGE II-3 The Periodic Table. Element- Any substance that can not be broken down into simpler forms Listed in squares w/basic items: Atomic number-

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Presentation on theme: "Science AHSGE II-3 The Periodic Table. Element- Any substance that can not be broken down into simpler forms Listed in squares w/basic items: Atomic number-"— Presentation transcript:

1 Science AHSGE II-3 The Periodic Table

2 Element- Any substance that can not be broken down into simpler forms Listed in squares w/basic items: Atomic number- # of protons (electrons as well- in a neutral atom); the smaller number Atomic Mass (Weight)- # of protons and neutrons in an atom; the larger number (sometimes a decimal) Neutrons= atomic mass – atomic number Atomic symbol- Letter(s) used to identify element Dmitri Mendeleev- First arranged by increasing atomic weight Henry Moseley- Correctly arranged by increasing atomic number

3 Atoms The simplest substances on Earth Nucleus- Center containing protons (positive charge) and neutrons (no charge) Electron cloud- Area surrounding nucleus where electrons (negative charge) are found in energy/electron levels/shells/orbits

4 The Periodic Table Horizontal rows= Periods (7) Share the same number of electron levels Reactivity decreases as you move left to right across a period Vertical columns= Groups or families (18) Share common physical and chemical characteristics Same number of valence electrons (electrons in the outermost level) HINT: The roman numeral in front of the A Reactivity increases as you go down the column Hydrogen does not belong to any family

5 The Periodic Table 3 main groups of elements: 1. Metals- On the left and middle of periodic table High hardness- Resists scratching Highly conductive- Allows for energy transfer Have luster- shiny 2. Metalloids- Along the zig-zag line Characteristics of metals and nonmetals 3. Non-metals- On the right side Brittle solids or gases Low conductivity No luster

6 Families IA- Alkali metals; one valence electron IIA- Alkaline Earth Metals; two valence electrons IIIB- IIB – Transition Metals IIIA- Boron group; three valence electrons IVA- Carbon group; four valence electrons VA- Nitrogen group; five valence electrons VIA- Oxygen group/Chalcogens; six valence electrons VIIA- Halogens/Halides; seven valence electrons VIIIA- Noble Gases; eight valence electrons

7 The Bohr Diagram A diagram of all electron shells in the electron cloud The first electron shell holds two electrons All other electron shells hold eight electrons Try these: 1. Lithium 2. Chlorine 3. Krypton 4. Nitrogen Which one of these does not work?

8 Lewis Dot Structure Diagram representing the valence electrons of an element Atomic symbol surrounded by dots on four sides Eight valence electrons total Put one dot per side and then double up Try these: 1. Xenon 2. Cesium 3. Gallium 4. Nitrogen

9 The Octet Rule and Ions All atoms, except for hydrogen and helium, require eight electrons in the outermost shell to become stable Noble gases are not reactive; already stable Ions- Atoms whose valence electrons have been gained or lost to reach this stability (charged particle) Gain electrons to reach eight- negative charge Lose electrons to drop back to shell behind that is already full- positive charge

10 Octet Examples Give the ionic charge for each of the following: (write the symbol with the charge) 1. Phosphorous 2. Potassium 3. Tellurium 4. Magnesium 5. Oxygen


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