an attractive force that links two atoms together in a molecule
form when atoms gain or lose one or more electrons to achieve stability; formed as the result of the electrical attraction between ions bearing opposite charges
an electrically charged particle that forms when an atom gains or loses one or more electrons
positively charged ions; Na+ has a charge of +1 because it has one less electron than it has protons
Negatively charged ions; Cl- has a charge of -1 because it has one more electron than it has protons
forms when two atoms attain stable electron numbers in their outermost shells by sharing one or more pairs of electrons.
Consider two hydrogen atoms coming in close proximity, each with an unpaired electron in its single shell. when the electrons pair up, stability occurs, forming the molecule H2
involves the sharing of a single pair of electrons
H-H or C-H
involves the sharing of four electrons (two pairs); C=C
six shared electrons- are rare, but there is one in nitrogen gas (N = N), which is a major component of the air we breathe.
The attractive force that an atomic nucleus exerts on electrons in a covalent bond
Nonpolar Covalent Bond
if two atoms are close to each other in electronegativity, they will share electrons equally
For ex) two oxygen atoms, each with an electronegativity of 3., will share electrons equally
when hydrogen bonds with oxygen to form water, the electrons involved are ..
Polar Covalent Bond
when electrons are drawn to one nucleus more than the other
bond resulting from the attraction of the negatively charged oxygen atom of one water molecule is attracted to the positively charged hydrogen atoms of other water molecules
hydrogen bonds contribute to the heat capacity of water. Raising the temperature of liquid water takes a lot of heat, because much of the heat energy is used to break the hydrogen bonds that hold the liquid together
Heat of Vaporization
Hydrogen bonding also gives water a high heat of vaporization, means that a lot of heat is required to change water from its liquid to its gaseous state. Evaporation has a cooling effect on the environment.
defined as the capacity of water molecules to resist coming apart from one another when placed under tension
groups of atoms that give important properties to biological molecules; each functional group has specific chemical properties, and when attached to a larger molecule, confer those properties on the larger molecule
large molecules; formed by covalent linkages of smaller molecules (Monomers)
formed from different combinations of 20 amino acids, all of which chemical similarities
can be giant molecules, and are formed by linking together chemically similar suger monnomers (monosaccharides) to form polysaccharides
are formed from four kinds of nucleotide monomers linked together in long chains
also form from large structures from a limited set of smaller molecules, but in this case noncovalent forces maintain the interactions between lipid monomers
In Condensation, the removal of water links monomers together
In hydrolysis, the addition of water breaks a polymer into monomers