What is the periodic table?
The Periodic Table
• Created by Dmitri Mendeleev
• Considered one of the greatest discoveries in
science
• Structures and properties of elements are
periodic – occurring repeatedly or at regular
intervals
Current Table
• 117 elements
• First 94 naturally occur
• Remaining 23 not found naturally on Earth
– Can be artificially created
– Americium – smoke detectors
• Left to right – metals, metalloids, nonmetals
• Nearly 80% are metals – shiny, bendable,
conductors of heat, electricity
• Nonmetals – dull, brittle, poor conductors
• Metalloids – between metal and nonmetal
How to Read the Table
• Chemical name
• Chemical symbol – abbreviation
– Can be based on its Latin name
• Atomic number – number of protons, top number
of square
– Increase in order from left to right, top to bottom
• Atomic weight – number of protons + neutrons,
number at bottom of square
– Number of neutrons = atomic weight – atomic
number
Periods and Groups
• Periods – a row in the periodic table
– Same number of atomic shells (cluster of orbitals)
– 1 to 7 (number of atomic shells)
• First shell closest to nucleus
• Shells layer like an onion
• Groups – column in the periodic table
– Same number of outer-shell electrons
– Tells how the element will combine with other
elements
Day 1
• 1. the number of protons, neutrons, and
electrons in an atom of an element
• 2. how electrons are arranged in orbitals
• 3. which elements are likely to react and
combine with each other
Day 2
•
•
•
•
A 1. shiny
2. can bend without breaking
3. good conductors of electricity
B 1. boron, silicon, germanium, arsenic,
antimony, tellurium, polonium, astatine
• 2. aluminum
• 3. hydrogen
Day 3
•
•
•
•
1. Cl, 17, 18, 17
2. Ca, 20, 20, 20
3. Fe, 26, 30, 26
4. Pb, 82, 125, 82
Day 4
•
•
•
•
A 1. 3
2. Mg, Al, Si, P, S, Cl, Ar
3. H, Li, K, Rb, Cs, Fr
B. The number of outer-shell electrons
determines how an element will combine with
other elements.