Simplest Matter

Elements

Elements

• Element- Matter made of only one kind of atom.– 112 known elements (92 naturally occur on Earth)

• 20 synthetic elements (made by scientists)

Periodic Table

• Chart used to organize and display the elements

• International system understood by scientists everywhere.

Periodic Table

• Elements organized on periodic table by their properties – Rows are called periods

• Elements in a row have same number of energy levels

– Columns are called groups• Elements in a column have similar properties

related to their structure also form similar bonds• (Same Valence Electrons!!!!!!!)

Identifying Characteristics

• Each element is different and has unique properties

• Atomic Number- Tells you the number of protons in the nucleus of each atom of that element.

• Mass Number- Number of protons plus the number of neutrons it contains.

• Atomic Mass- Weighted average mass of the isotope of an element.

• Isotope- Atoms of the same element that have different number of neutrons.

Classification of Elements

• 3 general categories: Metals, nonmetals, and metalloids

• Metals- Generally have a shiny or metallic luster and are good conductors of heat and electricity– All solid at room

temperature except mercury

– Malleable (bent or pounded into various shapes)

– Ductile (drawn into wires without breaking)

Classification of Elements

• Nonmetals- Usually appear dull in appearance and are poor conductors of heat and electricity.– Many are gasses at

room temperature– 97% of body is made

up of various nonmetals

Classification of Elements

• Metalloid- Elements that have characteristics of metals and nonmetals– Solid at room

temperature

Where Do Elements Come From?

• http://www.youtube.com/watch?v=zUDDiWtFtEM