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Unit II: Atoms and The Periodic Table

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1 Unit II: Atoms and The Periodic Table


3 intergalactic elements
EPISODE IIIIIIII PERIODIC HOPE In the dark days before the periodic table many rebel chemists tried in vain to organize the intergalactic elements UNTIL NOW.

4 Dmitri

5 History of the Periodic Table
Check out my original periodic table!


7 Mendeleev’s Periodic Table
Produced a table based on atomic weights but arranged 'periodically' with elements with similar properties under each other.

8 Mendeleev’s Periodic Table
Gaps were left for elements that were unknown at that time and their properties predicted (the elements were gallium, scandium and germanium). The order of elements was re-arranged if their properties dictated it, eg, tellerium is heavier than iodine but comes before it in the Periodic Table.


10 Modern Periodic Table Organized according to mass number rather than atomic masses This solved the “mass discrepancy” issue with certain elements where different isotopic abundances caused masses to be out of order E.g. Ar and K Co and Ni Te and I

11 Periodic Table – Periods

12 Periodic Table - Groups

13 States of Elements Purple = gas (g) Red = liquid (l)
Yellow = solid (s)


15 Periodic Table Some Metals
Alkali Metals

16 Alkali Metals Li, Na, K, Rb, Cs, Fr
These atoms each have one electron in their valence energy level They lose one electron to form a +1 ion Most active metals on the periodic table So reactive that they are never found as free elements

17 Periodic Table Some Metals
Alkaline Earth Metals

18 Alkaline Earth Metals Be, Mg, Ca, Sr, Ba, Ra
The atoms each have two electrons in their valence energy level They lose two electrons to form +2 ion

19 Periodic Table Transition Metals

20 Periodic Table Transition Metals

21 Periodic Table Transition Metals

22 Periodic Table Halogens

23 Halogens F, Cl, Br, I, At The atoms each have seven electrons in their valence energy level They gain one electron to form a -1 ion These elements are the most reactive non-metals


25 Periodic Table Noble Gases

26 Periodic Table Noble Gases
He, Ne, Ar, Kr, Xe, Rn Filled valence energy levels Do not easily combine with other atoms to form compounds Ar – most common noble gases ~ .93% air STABLE – NON REACTIVE



29 Metals shiny and solid at room temperature
Exception Mercury [only liquid] Conduct heat and electricity Tooled into sheets and wires [malleable and ductile]

30 Metals

31 Heavy Metals to any metallic chemical element that is dense and is toxic or poisonous at low concentrations  mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl), and lead (Pb).

32 Non-Metals Generally gases or dull, brittle solids at room temperature
Bromine is the only liquid Conduct heat and electricity poorly

33 Non-Metals

34 Metalloids=Semiconductors
Elements that have properties of both non-metals and metals Eg. B, Si, Ge, As, Sb, Te Important semi-conductors

35 Semiconductors Nonmetal having an electrical conductivity with increasing with temperature Silicon circuits in computers & electronics, solar photovoltaic cells

36 Trends in Metallic Properties
Metallic properties increase going from right to left Metallic properties increase going down the periodic table

37 Metallic properties increases as you move from right to left.
Metallic properties increases as you move down each column.

38 Trends in Metallic Properties

39 Bohr Models Diagram showing the number of protons and electrons in an atom or ion Can also include number of neutrons First Orbit Second Orbit Third Orbit Maximum number of electrons 2 8

40 Bohr Model

41 Bohr Model

42 Bohr Model Patterns Chemical families on the periodic table have the same number of valence electrons

43 Bohr Model Patterns Elements in the same period have the same number of shells Period number indicates the number of electron shells

44 Hebden Do In-Class Activity on Trends on the Periodic Table

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