C H E M I S T RY , M ATT E R A N D L I F E

CHAPTER 2

ELEMENTS

• Table 2-1 reviews all of the important elements you should be familiar with.

• Most important to living things (and this class) are:• CHNOPS

ATOMS

• Elements are different kinds of atoms. They are unique because of the number of PROTONS they contain.

• All atoms are made of PROTONS, NEUTRONS and ELECTRONS

ELECTRON AND BONDING

Since electrons circle the nucleus they are the particles that are involved in creating chemical bonds.

The outermost electrons are located in the outermost energy level, which typically wants to be filled with 8 electrons.

If an atom only has 5 electrons in its outermost energy level, it will want to find 3 more electrons to share.

MOLECULES AND COMPOUNDS

• A molecule is formed when two or more atoms are bonded together.

• A compound is a special type of molecule that is made of two or more different elements. (example: H2O, CO2)

WATER

• Most abundant compound in body• Critical in all physiologic processes in body

tissues• Deficiency (dehydration) can threaten health• Universal solvent• Stable liquid at ordinary temperatures• Participates in chemical reactions in body

MIXTURES

• Solution components• Indistinguishable from one another• Evenly distributed throughout (homogeneous)

• Suspension components• Separate from solvent• Settle out (heterogeneous or non-uniform)

• Colloid components• Separate from solvent• Evenly distributed throughout

CHEMICAL BONDS

• Electrons transferred between atoms form ionic bonds.• Electrolytes— ionic bonds

form compounds that release ions when they are in solution• Influence homeostasis (stable

condition of normal organism)• Conduct electronic current

COVALENT BONDS

A chemical bond in which atoms share electrons• Non-polar covalent bond• Polar covalent bond

ACIDS, BASES AND SALTS

Compounds are chemical substances with specific properties•Acid can donate hydrogen ion (H+) •Base (alkali) can accept hydrogen ion (H+)•Salt is formed by a reaction between an acid and a base

THE PH SCALE

• Represents relative concentrations of hydrogen and hydroxide ions in a solution

• Scale from 0 (most acidic) to 14 (most basic)

• Each unit represents a 10-fold change

• Body fluids usually 7.35-7.45 pH

BUFFERS

• Chemicals that prevent sharp changes in hydrogen ion concentration and maintain relatively constant pH in body fluids

• Blood is a good chemical buffer

ISOTOPES AND RADIOACTIVITY

Elements can exist in several forms (isotopes).• Same number of protons and electrons• Different number of neutrons• Different atomic weights• May be stable or unstable (radioactive)

USES OF RADIOACTIVITY

Radioisotopes are the rays given off by some radioactive elements.•Can penetrate and destroy cancer cells•Can aid in diagnosis

• X-rays• Tracers

CHEMISTRY IN LIVING THINGS

Living matter contains 26 of 92 natural elements.• 96% of body weight—four elements• 4% of body weight—nine elements• 0.1% of body weight—13 elements

ORGANIC COMPOUNDS

Chemical compounds that characterize living things• Contain carbon, hydrogen, and oxygen• Carbohydrates• Lipids• Proteins

CARBOHYDRATES

• Polysaccharides are broken down into monosaccharides to form glucose- which is broken down for and used for fuel

• Glycogen is stored in liver and skeletal muscles• Glycogenesis- making glycogen from glucose• Glycogenolysis- breaking down glycogen to make

glucose

LIPIDS

• Fatty Acids can be saturated or unsaturated• Unsaturated can be omega-3 or omega-4 fatty

acids• Important health implications

Fatty acids and glycerol are the preferred fuel source for many tissues

PROTEINS

• Most abundant macromolecule in the body• Contain CHON• Made of amino acids• 20 amino acids• Essential vs nonessential

MAJOR FUNCTIONS OF PROTEIN

• Support– Structural Protein

• Movement– Contractile Protein

• Transport– Transport (carrier)

• Buffering– Regulation of pH

• Metabolic Regulation– Enzymes

• Coordination and

Control– Hormones

• Defense– Antibodies

Enzymes are catalysts•Proteins that are not changed or used up in a reaction• Specific to a substrate• Limited by their saturation• Regulated by chemicals and hormones• Can be denatured by changes in temperature or pH