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.