The Chemistry of Life

What is stuff made of ? Matter is the “stuff” that makes up everything in the universe Matter is made up of Elements An Element is something that can not be broken down into smaller substances

Elements 112 known elements 90 of those are naturally occurring 22 are synthetic (made in a lab) 25 are essential for life Only 4 make up 96% OF ALL LIFE ON EARTH Carbon ( C ) Hydrogen (H) Oxygen (O) Nitrogen (N)

Elements

Parts of the atom Nucleus Electron Cloud Middle of the atom Contains the Protons(+) and Neutrons(0) Has a positive charge Electron Cloud The part of the atom outside the nucleus The region where the electrons are in an atom

Parts of the Atom

Electrons in atoms Electrons are arranged into energy levels around the nucleus The number of levels depend on the number of electrons an atom has The 1st level can hold a maximum of 2 electrons The 2nd level can hold a maximum of 8 electrons The 3rd level can hold a maximum of 18 electrons

Properties of an atom Most atoms by themselves are neutral Ions The # of Protons equals the # of Electrons Ions Atoms that do not have equal (+) and (-) More electrons will have a negative charge More protons will have a positive charge

Isotopes Isotopes are atoms of elements that have the same number of protons and electrons but different numbers of neutrons They are useful to scientist for Dating of fossils

Atom Vocabulary Atomic Number Mass Number Average Atomic Mass The number of protons an atom contains Mass Number The total number of protons and neutrons an atom contains Mass Number –Atomic No. = # of neutrons Average Atomic Mass The average mass of the element and its isotopes