The Periodic Table Chapter 5

Dmitri Mendeleev Russian chemist Created first adopted periodic table in the 1860’s

Mendeleev's Table Arranged elements in order of increasing mass Divided columns -elements with similar properties were in the same column Left gaps in the table for future discoveries

Atomic Mass Unit Average mass of an element and all of its isotopes Uses weighted averages All based around the standard of Carbon-12 Can change as new isotopes are discovered

Changes to Mendeleev's Table Periodic Law Elements are arranged by increasing atomic number since they NEVER change

Columns Referred to as groups or families Elements in the same column (1A etc.) behave in the same way Each column has same number of Valance electrons

Rows Called periods 7 total Period 1 is the top row and period 7 is the bottom row The number of the period = energy levels (rings)

Colors on the Table The colors indicate different types of elements Table can be broken down into 3 sections Metals Non-metals Metalloids

Non-Metals 17 elements Poor conductors of heat and electricity Many are gases at room temp If solid, brittle Right side of table plus H

Non-Metals Some non-metals are very reactive Fluorine**, Chlorine, Oxygen Most reactive nonmetals are in column 7 Some are NOT reactive at all All of column 8

Metalloids Have properties of both metals and non-metals Semiconductors Ability of conductor varies at temperature Location - 5,14,32,51,84 to the right

Metals Good conductors Solids (except for Hg) Mostly malleable Some are reactive some are not Most reactive are in column 1 Location – Left side of the periodic table

Variations Across a Period Left to Right: Elements become less metallic and more nonmetallic Right to Left: Elements become more reactive for metals Left to Right: Elements become more reactive for nonmetals

Groups Column 1A or IA (H-Fr) Alkali metals 1 valence e- Highly reactive Increase reactivity as you go down the family So reactive that they are hard to store

Column 2A or IIA Be-Ra Alkaline Earth Metals 2 valence e- Called Alkaline Earth Metals because they are materials often found in the Earth.

Column 3A or IIIA B-Tl Boron Family 3 valence e- Aluminum is the most abundant metal on earth

Column 4A or IVA C – Pb Carbon Family 4 valance e- Carbon is the most abundant element in your body

Column 5A or VA N – Bi Nitrogen Family 5 valence e- N and P are used in fertilizers (help plants grow)

Column 6A or VIA O-Po Oxygen Family 6 valence e- Oxygen is most abundant element in the earth’s crust

Column 7A or VIIA F-At Halogens 7 valence e Most reactive nonmetals All have similar chemical properties, not physical properties

Column 8A or VIIIA He-Rn Noble Gases Will not react with other elements 8 valence e- Used in neon signs and with elements that react with water

Transition Metals All the middle (1B – 8B) Form compounds with distinctive colors Separate 2 rows Called Rare Earth Metals Very similar to each other