Download Study Guide - Chapter 12 Quiz

Chapter 12 Study Guide - The Periodic Table
Dmitri Mendeleev A.. He arranged elements in order of atomic mass. He noticed that they had similar properties that occurred in a
repeating pattern, every 7 elements
B. He was able to predict the properties of elements not yet found.
Periodic - describes something that occurs or repeats at regular intervals
Henry Moseley - determined the number of protons, the atomic number, in an atom
A. Re-ordered the periodic table according to atomic number
Periodic law - states that the repeating chemical and physical properties of elements change periodically with the atomic
numbers of the elements
Metals - most elements are metals
A. most found to the left of the zigzag line
B. most have few electrons in their outer energy level
C. most are solid at room temperature
Nonmetals
A. found to the right of the zigzag line
B. most have an almost complete set of electrons in the outer level
C. More than half are gases at room temperature
Metalloids - also called semiconductors
A. border the zigzag line
B. about half of a complete set of electrons in the outer energy level
Each element is identified by a chemical symbol
Period - a horizontal row of elements in the periodic table
1. Most reactive elements on far left (alkali metals)
2. Least reactive elements on the far right (noble gases)
Group - a vertical column of elements in the periodic table
1. Elements in a group share chemical properties