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. 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

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Structure of an Atom

Nucleus

ProtonsAndNeutrons

electrons

- charge

_

+ charge

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)

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Isotopes

• Atoms of the same element that differ in their number of neutrons

• Some isotopes are unstable and give off radiation (radioisotopes)

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Radioisotopes

Uses of radioisotopes: • Used to treat cancer

(radiation kills cancer cells)

• Used to date fossils• Used in medical

imaging (radioactive tracers)

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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

Acids, Bases, and Buffers

What is an acid?-any substance that forms hydrogen ions (H+) in a solution

Examples of acids:HClH2SO4

HNO3

What is a base?-any substance that forms hydroxide ions (OH-) in a solution

Examples of bases:NaOHKOHCa(OH)2

pH Scale-measures the concentration of H+ ions in a solution

0 14

7ACIDIC BASIC

*A change is one on the pH scale represents a 10 fold increase in H+ ionsEx. pH of 3 is 10 times more acidic than pH 4 pH of 3 is 100 times more acidic than pH 5

PureH2O

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