Chapter Two

Matter  Living things are made up of matter! Example: Water, Fats, Proteins 6 elements most common to living things Carbon Hydrogen Oxygen Nitrogen Phosphorus Sulfur

Organic The 6 essential elements to life do not exist by themselves! They combine with other elements to form compounds. These compounds are called organic compounds!

Size Matters!  Smallest to Largest Subatomic Particles  Atoms  Elements  Compounds & Molecules  Matter

Subatomic Particles NameLocationChargeMassImportance

Subatomic Particles NameLocationChargeMassImportance Proton Neutron Electron

Subatomic Particles NameLocationChargeMassImportance ProtonNucleus – center of the atom Positive 11 amuIdentifies the atom # of protons = atomic number Neutron Electron

Subatomic Particles NameLocationChargeMassImportance ProtonNucleus – center of the atom Positive 11 amuIdentifies the atom # of protons = atomic number NeutronNucleusNo charge1 amuHelp determine the mass of an atom Mass = P + N Electron

NameLocationChargeMassImportance Proton Neutron ElectronAround the outside of the nucleus – electron cloud Negative 10 Do not contribute to the weight of an atom. Determine how the atom will behave

More on Electrons…  In a neutral atom (no charge) Electrons = Protons ○ How do we know how many protons an atom will have?  Electrons exist in different energy levels or shells. The first shell can hold a max. of 2 electrons. The 2 nd shell can hold a max of 8 electrons. The 3 rd shell can also hold a max of 8.

Atom Model  Write the elements symbol & # of protons in the middle.  Draw the first energy shell – 2 electrons  Draw 2 nd energy shell – add leftover electrons up to 8  Draw 3 rd shell if nec.  Ex:

More Atom Models SodiumChlorine

Reactivity  If the outer shell is full = not reactive The atom is stable!  If the outer shell is not full = The atom is not stable! Gain or Lose Electrons to fill its outer shell. Ion! Forming an Ion!

Ions  Atom with a charge  Charge = # protons - # electrons  Gain Electrons – atom is negative (anion)  More electrons (-) than protons (+)  Lose Electrons – atom is positive (cation)  More protons (+) than electrons (-)