Warm Up 9/24

1. Please get a blank periodic table from the front lab table and 3 different color crayons.

Origin of the Periodic Table

Mendeleev proposed the first arrangement of the periodic table.

Arranged by atomic mass

Found that as he arranged the elements, similar properties repeated themselves.

Mendeleev’s Periodic Table

Origin of the Periodic Table

There were “gaps” in his table, which led other scientists to discover new elements.

Moseley devised the current periodic table

which is based on ATOMIC NUMBER

The Current Periodic Table

Periodic means “repeating” pattern.

The periodic table groups similar elements together (think about sections in the grocery store).

Grouping makes it easier to predict the properties of an element.

Periods

Periods: horizontal rows of elements (7)

Just as the number of protons changes as you move from left to right across the periodic table, so does the number of electrons.

Remember that sentences are written in rows and end with a period.

Groups

Groups: Vertical column of elements on the periodic table (18)

Remember that group is spelled group and groups go up and down.

Elements in the same group have the same number of valence electrons (electrons in the last shell).

Responsible for atomic bonding

Equal to the last digit of the group number

How many valence electrons in this atom? What group would it be in?

Valence electrons

Groups

Valence electrons determine an element’s properties so all elements in the same group have similar properties.

What makes them different then???

Families of Elements

Think of each element as a member of a family that is related to other elements nearby.

Elements are classified as metals, nonmetals or metalloids

Groups are sometimes referred to as families

Metals

Physical Properties: Shiny (luster), good conductors, high density, ductile (can be made into thin wires), malleable (can be hammered into thin sheets) and most are silver

Chemical Properties: Corrosion (wearing away because of a chemical reaction with water), reactivity (bond with other atoms)

Metals

Nonmetals

Physical Properties: No luster, not conductors, brittle, not ductile, low density, and many are gaseous (can be solids or liquids too though)

Chemical Properties: Highly reactive

All, except for hydrogen, are on the right hand side of the periodic table.

Metalloids (Semconductors)

Properties: shiny or dull, conductors (but not as good as metals), ductile and malleable

There are only 6 total

Lanthanides and Actinides

Rare earth elements

Most of the actinides have been synthesized by nuclear scientists (except for uranium and thorium)

Periodic Trends Labeling Directions 1. Label the number of valence electrons at

the top of each group

2. Color the metals one color, the nonmetals one color and the metalloids another.

3. Label the following groups:

• Alkali Metals• Alkaline Earth Metals• Transition Metals • Boron Group• Carbon Group• Nitrogen Group• Oxygen Group• Halogens (only group with all 3 states of matter!)• Noble Gases• Lanthanides• Actinides

Types of Metals

1. Alkali Metals: very reactive

2. Alkaline-Earth Metals: form compounds that are found in our bodies (calcium and magnesium compounds)

3. Transition Metals: the properties gradually change from being more similar to Group 2 to being more like Group 13 (Gold, Silver and Platinum)