The Periodic Table

In 1860, grouped elements based on solitaire. Dmitri Mendeleev- In 1860, grouped elements based on solitaire. He arranged elements in increasing mass. Left spaces for new elements to be discovered.

Mendeleev’s Periodic Table DM’s periodic table had blank spaces where no known element would fit. Predicted the existence of undiscovered elements that would one day be found and fall into the blocks. He was correct!

Design of the Table Columns = families or groups. Elements in same family have similar prop. 18 total families, but only 8 main ones. Main Groups 1 2 3 4 5 6 7 8

Alkali Metal Family (Group 1) 1st family of periodic table All have 1 valence e- which they lose. Atom gets overall charge of +1. (Why?) Very reactive.

Alkaline Earth Metal Family (Group 2) 2nd family Have 2 valence e- which they lose. Get charge of +2. Very reactive.

Boron, Carbon, and Nitrogen Families Boron Family Have 3 valence e-. Form +3 charge. Carbon Family Have 4 valence e-. Get charge of +4 or +2. Nitrogen Family Have 5 valence e-. Get charge of -3

Oxygen Family, Halogens, and Noble Gases Have 6 valence e-. Form -2 charge. Halogens Have 7 valence e-. Form -1 charge. Noble Gases Have 8 valence e-. Stable / Unreactive Because their energy levels are full Do not gain or lose e-.

Transition Metals Transition metals Central area of periodic table. Most have 1 or 2 valence e-. Properties similar to each other and to other metals.

Rare Earth Elements At bottom of table. 1st Row = Lanthanide Series Put there to make the table shorter / easier to read. Similar to each other. 1st Row = Lanthanide Series 2nd Row = Actinide Series All actinides are radioactive.

Design of the Table Rows = periods. Elements in a period do not have similar props. Their properties repeat from period to period. There are 7 main periods. 1 2 3 4 5 6 7

Design of the Table Don’t mistake the two rows at the bottom of the table for periods!! They are separated out to make the table shorter and easier to read. They actually belong to the 6th and 7th periods.

Element Key 6 C carbon 12.011 atomic number chemical symbol Every table should have a key to tell you what each thing in an element’s box stands for. 6 atomic number C chemical symbol carbon element name 12.011 atomic mass

Properties of Elements Metals Metalloids Nonmetals

Metals – MOST of the Periodic Table Good conductors of heat and electric current High luster or sheen (shiny) Solids at room temperature (except for Hg) Ductile Malleable MORE REACTIVE ON LEFT

Nonmetals – upper right corner Variation in properties Not metals Mostly gases at room temperature Generally, poor conductors Solids tend to be brittle

Metalloids – the “stairstep” Properties similar to metals and nonmetals Behavior (metal or nonmetal) depends on conditions

Valence Electrons Valence e- Valence # Number of e- in the outer energy level of an atom. Determine the properties of an element. Valence # Bonding ability of the atom How many e- the atom will gain or lose when comb. w/ another atom Related to the charge of the ion Don’t get these two mixed up!

Valence Electrons vs Valence Number An oxygen atom has 6 valence electrons. But its valence number is 2. That’s because oxygen normally only forms 2 bonds with other atoms.

Check for Understanding Is the element at right a metal, metalloid, or non-metal? Answer: Metal How many valence electrons does this element have? Answer: 1 How many electrons will this element gain or lose? Answer: It will lose 1 electron. What is this element’s valence number? What charge will this element have when it gains or loses electrons? Answer: +1 11 Na Sodium 22.99

Check for Understanding Is the element at right a metal, metalloid, or non-metal? Answer: Non-metal How many valence electrons does this element have? Answer: 7 How many electrons will this element gain or lose? Answer: It will gain 1 electron. What is this element’s valence number? Answer: 1 What charge will this element have when it gains or loses electrons? Answer: -1 17 Cl Chlorine 35.45

Check for Understanding Is the element at right a metal, metalloid, or non-metal? Answer: Metal How many valence electrons does this element have? Answer: 3 How many electrons will this element gain or lose? Answer: It will lose 3 electrons. What is this element’s valence number? What charge will this element have when it gains or loses electrons? Answer: +3 13 Al Aluminum 26.98

Check for Understanding Is the element at right a metal, metalloid, or non-metal? Answer: Non-metal How many valence electrons does this element have? Answer: 8 How many electrons will this element gain or lose? Answer: It does not gain or lose electrons. What is this element’s valence number? Answer: 0 What charge will this element have when it gains or loses electrons? Answer: None 36 Kr Krypton 83.80

Check for Understanding Is the element at right a metal, metalloid, or non-metal? Answer: Metalloid How many valence electrons does this element have? Answer: 3 How many electrons will this element gain or lose? Answer: It will lose 3 electrons. What is this element’s valence number? What charge will this element have when it gains or loses electrons? Answer: +3 5 B Boron 10.81