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Biochemistry. Particles of Matter. An element is a substance made of only one type of atom A compound is made of more than one type of atom (ex. CO 2 , H 2 O) An atom is the smallest part of an element that has the same properties as the element A molecule is the smallest
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Particles of Matter • An element is a substance made of only one type of atom • A compound is made of more than one type of atom (ex. CO2, H2O) • An atom is the smallest part of an element that has the same properties as the element • A molecule is the smallest part of a compound that has the same properties as the compound
Structure of an Atom - charge Nucleus Protons And Neutrons + charge electrons 0 charge _
Sub-Atomic Particles • Protons and neutrons make up the mass of the atom (atomic mass) • The arrangement of electrons determines the chemical properties of the atom (how it behaves in a chemical reaction)
Isotopes • Atoms of the same element that differ in their number of neutrons • Some isotopes are unstable and give off radiation (radioisotopes)
Radioisotopes Uses of radioisotopes: • Used to treat cancer (radiation kills cancer cells) • Used to date fossils • Used in medical imaging (radioactive tracers)
What is an ION? • An atom or group of atoms with a charge (either + or -) • Ions are involved in thousands of chemical processes in the body
What is an acid? • any substance that forms • hydrogen ions (H+) in a solution Examples of acids: HCl H2SO4 HNO3
What is a base? • any substance that forms hydroxide ions (OH-) in a • solution Examples of bases: NaOH KOH Ca(OH)2
pH Scale • measures the concentration of H+ ions in a solution Pure H2O BASIC ACIDIC 7 0 14 *A change is one on the pH scale represents a 10 fold increase in H+ ions Ex. pH of 3 is 10 times more acidic than pH 4 pH of 3 is 100 times more acidic than pH 5
What is a Buffer? • A buffer is a substance that neutralizes excess acids or bases to keep the pH of a solution constant • Buffers are present in all of the cells and fluids in your body