CHEMISTRY, WATER, AND PHChapter 2

THE BASICS Matter is anything that takes up space and has

__________ The fundamental unit of matter is the _______. Atomic theories The most important constituent parts of an atom

are

Atoms are usually neutral Organization of the atom

electronshell

electron(negative charge)

proton(positive charge)

neutron(no charge)

nucleus

Hydrogen (H) Helium (He)

ELEMENTS

An element is any substance that cannot be reduced to any simpler set of constituent substances through chemical means.

Each element is defined by the number of protons in its nucleus= _______________Difference between iron and gold?

The number of _____________in an atom can vary independently of the number of ________________.

A single element can exist in various forms, called ____________, depending on the number of _____________it possesses.

Mass number = _____________+ ___________________

_____________________is the average mass number of isotopes for one element.

CHEMICAL BONDING

________________: atoms share one or more electrons ________________: atoms lose and accept electrons

from each other Atoms “seek” their ____________energy state. This happens when it has a filled

_____________________. Hydrogen and helium need _____ e- to be “full” Most elements need ____ e- to have filled outer

shells. A molecule

________________________________________________________________________ Water molecule

Atoms of different elements differ in their power to attract electrons= _____________.

With this, a molecule can take on a _____________—a difference in electrical charge at one end compared to the other.

Covalent chemical bonds can be polar or nonpolar. A _________________________exists when shared

electrons are not shared equally among atoms in a molecule

Two atoms will undergo a process of ____________________when the electronegativity differences between them are great enough that one atom loses 1 or more electrons to the other.

_______: atoms whose number of electrons differs from their number of protons.

The charge differences can produce an electrostatic attraction between ions = ______________

When atoms of two or more elements bond together _____________, the result is an ______compound.

____________ bonding links an already covalently bonded hydrogen atom with an electronegative atom.

MOLECULAR SHAPE MATTERS

The three-dimensional molecular shape is important in biology because it determines the capacity molecules have to bind with one another.

Review of molecular models

WHY WATER IS SO IMPORTANT IN BIOLOGY Required/generated by many cellular reactions

Water is a powerful _____________, with the ability to dissolve more compounds in greater amounts than any other liquid.

DENSITY DIFFERENCES

Solid versus liquid densities, important for marine organisms.

_________ is less dense than _________. Bodies of water in colder climates do not freeze

solid in winter. Allows life to flourish under the ice.

SPECIFIC HEAT

Water has a great capacity to absorb and retain heat.

The oceans act as _____________for the Earth, thus stabilizing Earth’s temperature.

Desert

Body temperature

Inland vs shore

COHESION AND SURFACE TENSION

Cohesion: Creates surface tension: water molecules below

the surface are equally attracted in all directions to other water molecules.

At surface, no attraction to air above, so are pulled down and to the side by other water molecules

Important biologically:

HYDROPHILIC AND HYDROPHOBIC

Hydrophobic: A.k.a. Example:

Hydrophilic: A.k.a. Example:

ACIDS AND BASES

An acid ____________H+ when put in aqueous solution.

A base _____________H+ in solution. A base added to an acidic solution makes that

solution ________ acidic. An acid added to a basic solution makes that

solution ________basic. _________________ can act as either an acid or a

base.

PH

pH < 7 is ___________; pH > 7 is _________, pH = 7 is __________

The lower the pH, the more __________the solution; the higher the pH, the more _________the solution

1 pH unit corresponds to a _____________________difference in acidity

pH= pOH = buffers

http://www.youtube.com/watch?v=TfDVLsBXYcM

WHY DO WE CARE ABOUT PH IN BIOLOGY?

Cell membranes

Reaction rates

Asthma

Heart burn/acid reflux

Cardiac arrest

Acidosis

Acid rain