CHEMICAL BASIS OF LIFE
Molecules and Compounds
Molecule
- 2 or more atoms chemically combine
Basic Chemistry - Example: water (H2O)
Chemistry – concerned with atomic composition, structure Compound
of substances, and reactions they undergo - chemical combination of 2 or more different types of
Matter - anything that occupies space and has mass atoms
(solid, liquid, or gas) - Example: NaCl
Mass - amount of matter in an object Dissociation – separation of ions in an ionic compound by
polar water molecules
Weight - gravitational force acting on object
Electrolytes – dissociated ions
Elements and Atoms
Element - simplest form of matter
Chemical reactions occur when there is a formation or
Example: C, H, O, N, Ca, K, Na, Cl
breaking of chemical bonds between atoms, ions,
molecules, or compounds
Atom - smallest particle of an element
- contains protons, electrons,
and neutrons Reactants: substances that enter into the reaction
Atomic Structure Products: substances that result from the reaction
Proton - positive charged particle (inside)
Types of Chemical Reactions
Neutron - neutral charged particle (inside Synthesis reaction
• build a new molecule
Electron - negative charged particle (outside) • energy-requiring
• Example: ADP + P → ATP
Atomic number - the number of protons in each atom Decomposition reaction
• break down molecule
Mass number - the number of protons + neutrons • energy-releasing
• Example: ATP → ADP + P
Electrons and Chemical Bonding Exchange reaction
Chemical bonds - occur when outermost electrons are • combination of synthesis and decomposition
transferred or shared between atoms reactions
• Example: AB + CD → AC + BD
Types of chemical bonds • Example: HCl + NaOH → NaCl + H2O
• Ionic
• Covalent Reversible reactions occur when the reaction can run in
• Hydrogen the opposite direction, so that the products are converted
back to the original reactants.
Ionic bond - attraction between two oppositely charged CO2 + H2O ⇄ H+ + HCO3
ions
Ion: a charged atom formed because of a donation Equilibrium: when the rate of product formation equals the
or gain of an electron rate of reactant formation
Example: NaCl
Energy
Covalent bond - occurs when atoms share one or more
pairs of electrons - Energy is the capacity to do work
Example: hydrogen molecule (H2) - Work is the moving of matter
1. Polar covalent bonds - unequal sharing of - Kinetic energy is energy in motion
electrons; asymmetrical
- like water, have a positive end and a negative end Potential energy - stored energy
Example: water (H2O)
Chemical energy is a form of potential energy stored in
2. Nonpolar covalent bonds – equally shared,
chemical bonds.
symmetrical
- may require or release energy.
Less reactants that products = need energy
Hydrogen Bond
ADP + Pi + energy from food → ATP
- weaker bond
More reactants than products = release energy
- no exchange of electrons is involved
ATP → ADP + Pi + energy
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Molecules and Compounds
Molecule
- 2 or more atoms chemically combine
Basic Chemistry - Example: water (H2O)
Chemistry – concerned with atomic composition, structure Compound
of substances, and reactions they undergo - chemical combination of 2 or more different types of
Matter - anything that occupies space and has mass atoms
(solid, liquid, or gas) - Example: NaCl
Mass - amount of matter in an object Dissociation – separation of ions in an ionic compound by
polar water molecules
Weight - gravitational force acting on object
Electrolytes – dissociated ions
Elements and Atoms
Element - simplest form of matter
Chemical reactions occur when there is a formation or
Example: C, H, O, N, Ca, K, Na, Cl
breaking of chemical bonds between atoms, ions,
molecules, or compounds
Atom - smallest particle of an element
- contains protons, electrons,
and neutrons Reactants: substances that enter into the reaction
Atomic Structure Products: substances that result from the reaction
Proton - positive charged particle (inside)
Types of Chemical Reactions
Neutron - neutral charged particle (inside Synthesis reaction
• build a new molecule
Electron - negative charged particle (outside) • energy-requiring
• Example: ADP + P → ATP
Atomic number - the number of protons in each atom Decomposition reaction
• break down molecule
Mass number - the number of protons + neutrons • energy-releasing
• Example: ATP → ADP + P
Electrons and Chemical Bonding Exchange reaction
Chemical bonds - occur when outermost electrons are • combination of synthesis and decomposition
transferred or shared between atoms reactions
• Example: AB + CD → AC + BD
Types of chemical bonds • Example: HCl + NaOH → NaCl + H2O
• Ionic
• Covalent Reversible reactions occur when the reaction can run in
• Hydrogen the opposite direction, so that the products are converted
back to the original reactants.
Ionic bond - attraction between two oppositely charged CO2 + H2O ⇄ H+ + HCO3
ions
Ion: a charged atom formed because of a donation Equilibrium: when the rate of product formation equals the
or gain of an electron rate of reactant formation
Example: NaCl
Energy
Covalent bond - occurs when atoms share one or more
pairs of electrons - Energy is the capacity to do work
Example: hydrogen molecule (H2) - Work is the moving of matter
1. Polar covalent bonds - unequal sharing of - Kinetic energy is energy in motion
electrons; asymmetrical
- like water, have a positive end and a negative end Potential energy - stored energy
Example: water (H2O)
Chemical energy is a form of potential energy stored in
2. Nonpolar covalent bonds – equally shared,
chemical bonds.
symmetrical
- may require or release energy.
Less reactants that products = need energy
Hydrogen Bond
ADP + Pi + energy from food → ATP
- weaker bond
More reactants than products = release energy
- no exchange of electrons is involved
ATP → ADP + Pi + energy
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