Chapter 2: The Chemistry of Life

Matter

• Anything that has mass and occupies space 

Chemistry

• Study of matter and its interactions 

Atom

• Smallest unit of matter that still retains its original properties

• a group of these makes a element

Element

• Substance composed of one or more identical atoms; Cannot be broken down into simpler substances by chemical means

Protons(p+)

• Positively charged particles that reside in the central core, or Atomic Nucleus, of the atom

Neutrons(n0)

Uncharged particles that are slightly larger than protons and also reside in the atomic nucleus

Electrons(e-)

Negatively charged tiny particles that surround the atomic nucleus

Electron Shell( 1st Shell)

closest to the atomic nucleus, can hold 2 electrons

Electron Shell( 2nd Shell)

can hold 8 electrons

Electron Shell( 3rd Shell)

can hold 18 electrons but is satisfied with 8

Atomic Number

Elements that are defined by the number of protons in the atomic nucleus

Chemical Symbols

element abbreviations

4 major elements that make up (96%) of body mass

oxygen(o)=65%,

Carbon (C) = 18%,

Hydrogen (H) = 10%,

Nitrogen (N) = 3%

7 mineral Elements(less than 4%)

Sodium (Na), Potassium (K), Calcium (Ca), Chlorine(Cl), Magnesium (Mg), Phosphorus (P), and Sulfur (S)

13 Trace Elements

Iron (Fe), Copper (Cu), Iodine (I), Zinc (Zn), and others

mass number

The sum of all protons and neutrons in the atomic nucleus (shown top left of element symbol)

Isotope

Atom with the same number of protons (atomic number) but different number of neutrons (mass number)

Radioisotopes

Unstable isotopes that release energy as radiation; Form the basis for nuclear medicine

Mixture

Atoms of 2 or more elements are physically intermixed; The chemical nature of the atoms does not change; The atoms may be physically separated

Molecules

Two or more atoms are combined by chemical means; The molecule has different properties from those of the original atoms; Can only be separated by chemical means

3 basic types of Mixtures

Suspensions- Liquid mixed with a solid; Large solid particles are visible and will settle out of the mixture

Colloids- Liquid mixed with a solid; Small solid particles are not visible so appears opaque; Particles remain dispersed

Solutions- Liquid (usually water) mixed with a solid, liquid, or gas; One substance dissolves (solute) in another (solvent) so appears translucent

Chemical Bonds

An energy relationship, or attractive force, between atoms

Compound

Forms when 2 or more atoms of different elements are chemically bonded

Macromolecules

Very large compounds composed of many atoms

Valence Electrons

Chemical bonds form when valence electrons in the outermost shell, called the Valence Shell, of atoms interact

Octet Rule

an atom is most stable with 8 electrons in the valence shell

Duet Rule

Exceptions for atoms with 5 or fewer electrons, and they are most stable with 2 electrons in the first shell

Ionic Bond

Electrons are transferred between a metal atom and a nonmetal atom

Ion

When an atom gains or loses an electron, it is no longer neutral, it is charged

Cation

Positively charged ion

Anion

Negatively charged ion

Covalent Bond

Electrons are shared between two or more nonmetal atoms; This is the strongest type of chemical bon

Two atoms can share

1 electron= single Bond

2 electrons= double bond

3 electrons= triple bond

Nonpolar Covalent Bond

Electrons are shared equally

Polar Covalent Bond

Electrons are shared unequally

Dipoles

Polar molecules with partially positive and partially negative ends

Hydrogen Bonds

Weak attractions (not bonds) between the partially positive atoms and partially negative atoms in polar covalent molecules

• seen in DNA

Energy

• The capacity to do work; Energy can put matter into motion; Fuels our chemical reactions

Potential energy

Energy that is stored, ready to be released and used to do work

Kinetic energy

energy in motion

Chemical Energy

• Energy in chemical bonds; Electrons are always in motion; Drives cellular processes

Electrical Energy

Generated by movement of charged ions

Mechanical Energy

• Energy directly transferred from one object to another 

Endergonic Reaction

Require one or more forms of energy from another source to proceed; Products will contain more energy than reactants because energy was invested

Exergonic Reactions

• Excess energy stored in the reactants is released during the reaction

Catabolic Reactions

• Larger substances are broken down into smaller ones( breaking down food or damaged cells)

Exchange Reactions-

• Transfer of atoms or electrons between reactants (converting the energy in food into a usable form)

Anabolic Reactions

• Form new chemical bonds (building new compounds such as new cells and tissues)

Catabolic Reactions

• Generally exergonic( AB→A+B)

Exchange Reaction

• Bonds are broken and formed(AB+CD→AD+BC)

Oxidation- reduction(Redox) Reactions

• Involves electron exchange instead of atoms; Exergonic

  • Reactant that loses electrons is Oxidized

  • Reactant that gains electrons is Reduced

Anabolic Reactions-

• Generally endergonic(A+B→AB)

Activation Energy(Ea)

is the energy required to allow strong collisions of the electrons of atoms of reactants in a chemical reaction; Must overcome the repulsion of the electrons of atoms to each other

Concentration

• Increased reactant concentration increases collisions between particles

Temperature

• Increased temperature increases kinetic energy of atoms (limits in physiological systems)

Properties of Reactant

• Size and phase (solid, liquid, or gas) influences reaction rates; Small particles and gas particles have higher kinetic energy 

Presence or Absence of a Catalyst

• Catalysts lower the activation energy of a reaction; Biological catalysts are called Enzymes

Enzymes

Increase the rate at which all types of reactions occur; Nearly all are proteins with the following properties

• Lowers the Activation Energy

Energy

the capacity to do work; Energy can put matter into motion; Fuels our chemical reactions

Potential energy

Energy that is stored, ready to be released and used to do work

Kinetic Energy

Energy in motion

Chemical Energy

Energy in chemical bonds; Electrons are always in motion; Drives cellular processes

Electrical Energy

Generated by movement of charged ions

Mechanical Energy

Energy directly transferred from one object to another

Endergonic Reactions

Require one or more forms of energy from another source to proceed; Products will contain more energy than reactants because energy was invested

Exergonic Reactions

Excess energy stored in the reactants is released during the reaction

Catabolic Reactions

Larger substances are broken down into smaller ones (e.g., breaking down food or damaged cells)

Exchange Reactions

Transfer of atoms or electrons between reactants (e.g., converting the energy in food into a usable form)

Anabolic Reactions

Form new chemical bonds (e.g., building new compounds such as new cells and tissues)

Catabolic Reactions

Generally exergonic(( AB→A+B)

Exchange Reaction

Bonds are broken and formed(AB+CD→AD+BC)

Oxidation reduction(Redox) Reactions

Involves electron exchange instead of atoms; Exergonic( Oxidized= reactant that loses electrons/ Reduced= reactant that gains)

Anabolic Reactions

Generally endergonic(A+B→AB)

Activation Energy(Ea)

the energy required to allow strong collisions of the electrons of atoms of reactants in a chemical reaction; Must overcome the repulsion of the electrons of atoms to each other

Concentration

Increased reactant concentration increases collisions between particles

Temperature

Increased temperature increases kinetic energy of atoms (limits in physiological systems)

Properties of Reactants

Size and phase (solid, liquid, or gas) influences reaction rates; Small particles and gas particles have higher kinetic energy

Presence or Absence of a Catalyst

Catalysts lower the activation energy of a reaction; Biological catalysts are called Enzymes

Enzymes

Lowers the Activation Energy

Enzyme Properties

Highly specific, contains the Active Site, doesn't alter chemical reaction, and not permanently altered

Biochemistry

the chemistry of life

Inorganic Compounds

Do not contain carbon bonded to hydrogen; Important inorganic compounds in the body include water, acids, bases, and salts

Organic Compounds

Do contain carbon bonded to hydrogen