Physical Science / Unit 3: Atoms and the Periodic Table
3.4 Organization of the Periodic Table
Notes
The periodic table arranges elements in order of increasing atomic number.
- Mendeleev built an early version by arranging elements by atomic mass and properties; the modern table uses atomic number.
- Periods are the horizontal rows (7 of them). Groups (families) are the vertical columns (18 of them).
- Elements are sorted into metals (left and middle; shiny, conduct well), nonmetals (right; dull, poor conductors) and metalloids (along the staircase line; in between).
- Periodic law: properties repeat in a pattern as atomic number increases.
Practice
How are the elements arranged in the modern periodic table?
The modern table orders elements by number of protons.
What do we call a vertical column in the periodic table?
Elements in the same group share similar properties.
Silicon is shiny like a metal but is a poor conductor and brittle like a nonmetal. It is probably a:
Metalloids have properties of both metals and nonmetals.
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