Elements and Compounds

Learning Target Today we will classify matter as Elements Elements Compounds Compounds Or mixtures Or mixtures

Bellwork: List 5 ways your friends can distinguish you in a crowd (physical properties)

Elements A pure substance A pure substance Can not be separated into simpler substances by physical or chemical means Can not be separated into simpler substances by physical or chemical means

Elements 92 naturally occurring elements 92 naturally occurring elements Copper Copper Oxygen Oxygen Several man made elements Several man made elements Einstienium Einstienium Californium Californium

Elements are not naturally abundant Hydrogen makes up 75% of the mass of the universe Hydrogen makes up 75% of the mass of the universe

Elements are not naturally abundant Silicon and Oxygen together make up 75% of the mass of the Earth’s crust Silicon and Oxygen together make up 75% of the mass of the Earth’s crust

Elements are not naturally abundant Oxygen, Carbon, and Hydrogen make up 90% of the mass of a human body Oxygen, Carbon, and Hydrogen make up 90% of the mass of a human body

Periodic Table Organizes elements into a grid: Organizes elements into a grid: Periods (horizontal rows) Periods (horizontal rows) Families or Groups (vertical columns) Families or Groups (vertical columns) Elements in the same group have similar properties. Elements in the same group have similar properties.

Atoms Atom – The smallest unit of an element that maintains the properties of that element

Compound A substance made from two or more elements that are chemically bonded A substance made from two or more elements that are chemically bonded Compounds consist of molecules

Compounds There are over 1 million known chemical compounds There are over 1 million known chemical compounds Some naturally occurring Some naturally occurring Some synthetic (man made) Some synthetic (man made) More discovered or synthesized each year! More discovered or synthesized each year!

Molecules Molecules are the smallest particles a compound can be divided into without changing it’s chemical properties. (without changing what it is)

Chemical Alphabet Give me a word… Give me a word… A word is made of letters A word is made of letters Letters can not be broken into anything smaller that have meaning. Letters can not be broken into anything smaller that have meaning. Think of atoms as letters Think of molecules as words. Atoms are the pieces that make up molecules.

Each atom has it’s own symbol

Chemical Alphabet A molecule is made of atoms A molecule is made of atoms Each atom has it’s own symbol Each atom has it’s own symbol Atoms can not be broken into anything smaller that have meaning. Atoms can not be broken into anything smaller that have meaning.

H = Hydrogen O = Oxygen 2 H atom + O atom combine  1 water molecule  1 water molecule H2OH2OH2OH2O

C = Carbon O = Oxygen 1 C atom + 2 O atoms combine  1 Carbon Dioxide molecule  1 Carbon Dioxide molecule CO 2

Element or Compound? Gold (Au) Gold (Au) Sugar (C 6 H 12 O 6 ) Sugar (C 6 H 12 O 6 ) Nitrogen (N 2 ) Nitrogen (N 2 ) Sand (Si-O 2 ) Sand (Si-O 2 ) Silicone Dioxide Silicone Dioxide Table Salt (Na-Cl) Table Salt (Na-Cl) Sodium Chloride Sodium Chloride Iron (Fe) Iron (Fe) Oxygen (O 2 ) Oxygen (O 2 ) Rust (Fe 2 O 3) Rust (Fe 2 O 3) Iron Oxide Copper (Cu) Copper (Cu) Chlorine (Cl 2 ) Chlorine (Cl 2 )

Pure Substances Elements and compounds are Pure Substances. Elements and compounds are Pure Substances. Pure substances have fixed composition and definite properties. Pure substances have fixed composition and definite properties. Ex: Water Ex: Table Salt

Pure Substances NaCl  Na + Cl… pretty harmless NaCl  Na + Cl… pretty harmless Sodium metal explodes in water!Gas masks to protect from poisonous Chlorine gas

The Point…. A compound has very different properties from the elements it is made of Both are pure substances!