Chapter 2: Chemical Bonds and Reactions
activation energy
The collision energy needed to break the chemical bonds of reactants.
ionic bond
The force of attraction that holds ions with opposite charges together.
reduction
The gain of electrons; the reduced substance gains energy during the process
oxidation
The loss of electrons; process releases energy
electronegativity
The power of an atom to attract electrons to itself.
reactant
The starting substances of a chemical bond
cohesion
The tendency of like particles to stay together
polar covalent bond
Two atoms share electrons unequally; one atom attracts electrons more strongly than the other.
single covalent bond
Two atoms share one electron pair.
double covalent bond
Two atoms share two electron pairs
octet rule
Two or more atoms can interact in ways that produce chemically stable arrangements of 8 valence electrons for each atom; explains why atoms will interact in predictable ways.
surface tension
A measure of the difficulty of stretching or breaking the surface of a liquid.
anion
A negatively charged ion
endergonic reaction
Absorbs more energy than it releases
temperature
An increase causes particles to move around more rapidly; increasing the likelihood that atoms will collide.
catalyst
Chemical compounds that speed up chemical reactions by lowering the activation energy needed for a reaction to occur; also helps orient the colliding particles. Most important in the body are enzymes.
reversible reaction
Chemical reaction where the products can revert to the original reactants. ie: AB breaks down into A+B; A+B can combine to form AB.
valence shell
Contains electrons, the number of which determine if an atom will form a chemical bond with another atom. Containing 8 electrons is chemically stable and unlikely to bond with other atoms.
product
Ending substances of a chemical bond
law of conservation of energy
Energy cannot be created or destroyed; it may be converted from one form to another.
concentration
More particles of matter in a confined space; increases the likelihood that atoms will collide.
chemical reaction
Occurs when new bonds form or old bonds break between atoms. The total mass of the reactants = the total mass of the products.
exergonic reaction
Releases more energy than it absorbs
triple covalent bond
Two atoms share three electron pairs
covalent bond
Two or more atoms sharing electrons instead of gaining or losing electrons; may form between same or different elements; most common chemical bond in the body forming most of the body's structures.
non polar covalent bond
When two atoms share electrons equally; one atom does not attract electrons more strongly than the other one. Always occurs between two identical atoms.
synthesis reaction
When two or more atoms, ions or molecules combine to form new and larger molecules; collectively referred to as anabolism; usually endergonic.
cation
A positively charged ion
oxidation-reduction reaction
Always parallel; when one substance is oxidized, another is reduced at the same time.
electrolyte
An ionic compound that breaks apart into positive and negative ions.
exchange reaction
Body reactions that consist of both synthesis and decomposition.
hydrogen bond
Result from the attraction of oppositely charged parts of molecules instead of sharing electrons; weak compared to ionic and covalent bonds; cannot bind atoms into molecules
investment
Energy needed to start a chemical reaction
chemical bonds
Forces that hold together the atoms of a molecule or compound.
chemical energy
Form of potential energy that is stored in the bonds of molecules and compounds.
decomposition reaction
Split up large molecules into smaller atoms, ions or molecules; collectively referred to as catabolism; usually exergonic.