CHEMISTRY

Elements

An element is a substance that cannot be broken down into simpler substances by chemical means

Examples of elements: Hydrogen, Oxygen, Gold, Neon

Everything is made of elements

There are 118 elements

All elements are arranged in the Periodic Table

The Periodic Table

The periodic table was created by Dmitri Mendeleev in 1868

There were only 63 known elements at this time

Mendeleev is known as the father of the Periodic Table

Elements are arranged from left to right and top to bottom in order of increasing atomic number.

Order general coincides with increasing atomic mass

The different rows of elements are called periods

The rows going across are called periods

The columns going up and down are called groups

There are 10 groups on the periodic table

The groups are: Alkai metals, Alkaline earth metals, transition metals, basic metals, semi-metal, lanthanides, actinides, non-metals, halogens, and noble gases

Alkali Metals

Located in Group IA Include lithium,

sodium, potassium, rubidium, cesium, and francium

Highly reactive Lower densities

Alkaline Earth Metals

Located in group II Include Magnesium,

Beryllium, Calcium, Strontium, Barium, and Radium

Transition Metals

Located in groups IB to VIIIB

Very hard High melting points High boiling points Malleable Conducts electricity

Basic Metals

Most of the elements on the periodic table are metals

Shiny solids Solid at room

temperature Conducts electricity

and temperature

Metalloids or Semimetals

Includes: boron, silicon, germanium, arsenic, antimony, and tellurium

The boiling and melting points vary widely

Good semiconductors

Non-Metals

Located on the upper right side of the periodic table

Poor thermal conductors

Poor electrical conductors

Solid non-metals are generally brittle

They lack metallic luster

Halogens

Group VIIA of the periodic table

Halogens are fluorine, chlorine, bromine, iodine, astatine, and unuseptium.

Highly reactive, especially with alkali metals and alkaline earth metals

Noble Gases

Group VIII of periodic table

Sometimes called Group O

Non-reactive Low boiling point All gases at room

temperature

Lanthanides

Rare earth metals Form during the

fission of uranium and plutonium

Silvery-white metals Relatively soft Very reactive

Actinides

All are radioactive Metals tarnish readily

in air Very dense metals React with boiling

water Combine with most

nonmetals