- Mendeleev
- arranged the elements in order of increasing atomic masses
- found their was a pattern to the properties of the elements, hence, the Periodic Table
- had blank spaces for elements not yet discovered
- accurately predicted the properties of these elements
- Moseley
- arranged the elements in order of increasing atomic numbers
- way we organize the periodic table today
- vertical columns are called groups or families
- each group of elements have similar properties because they have the same outer number of electrons
- horizontal rows are called Periods
- Elements within the same period do not have similar properties
- elements to the left of the stairstep line are metals
Metals- include transition metals , and inner transition metals(lanthanoids and actinoids)
- are solids at room temperature (except Hg)
- have a high luster(are shiny) when clean
- are good conductors of heat and electricity
- are ductile (can be drawn into thin wires)
- are malleable(can be flattened into sheets)
- elements to the right of the stairstep line are nonmetals
Nonmetals- are gases or brittle solids at room temperature (except Br)
- do not conduct heat or electricity well
- elements next to the stairstep line are metalloids
- metalloids have properties of both metals and nonmetals.
- Most modern sources use the 1-18 means of labeling the families (including Glencoe Physical Science)
- Addison-Wesley Chemistry uses the A/B labeling
- representative elements(and group 0) are the group A elements
- group B elements are the transition metals
- Both forms of labeling are in the chemistry book on page 108
- Be familiar with both, as different standardized tests use different versions
No big deal, just check out the periodic table included as a reference first - Arrangements of the elements are the same, just the headings are different
- Check out this interactive Periodic Table on-line!
This one from Chemicool is also worth taking a look at.
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