BASIC CHEMISTRYBASIC CHEMISTRY

Why study Chemistry in Biology?

Biology - study of LIFE! Chemistry - part of chemistry

deals with chemical compounds…. And chemical compounds are important to living things.

Ex: glucose- C6H12O6

water - H2O salt - NaCl

Composition of Matter

Matter - Everything in universe is composed of matter Matter is anything

that occupies space or has massMass – quantity of matter an object has

Weight – pull of gravity on an object

ElementsElements Pure

substances that cannot be broken down chemically into simpler kinds of matter

More than 100 elements (92 naturally occurring)

Each element unique chemical symbol

Consists of 1-2 letters First letter is always capitalized

99% of the mass of an organism is composed of 6 elements (SPONCH)

sulfur (S), phosphorus (P), oxygen (O), nitrogen (N), carbon (C), hydrogen (H) Remaining 1% is composed of trace

elements required by an organism in minute amounts.

Iron (Fe) Iodine (I) Copper (Cu) Zinc (Zn)

AtomsAtoms The simplest

particle of an element that retains all the properties of that element

Our understanding of the structure of atoms based on scientific models, not observation

The ProtonsThe Protons Contain a positive charge Located in the nucleus of an atom # of protons known as the atomic #. Number of protons balanced by an

equal number of negatively charged electrons

The NeutronsThe Neutrons Are neutral Located in the nucleus of an atom

The ElectronsThe Electrons Negatively charged high

energy particles with little or no mass

Travel at very high speeds at various distances (energy levels) from the nucleus

Determine the reactivity of an element.

The NucleusThe Nucleus Central core Consists of

positive charged protons and neutral neutrons

Positively charged

Contains most of the mass of the atom

Atomic Number ALWAYS equal

to the # of protons.

Most of the time is = the # of e- (unless it has become an ion)

Is ALWAYS constant!!! This # identifies the element.

Atomic Mass The atomic mass of an atom is found by

adding the number of protons & neutrons in an atom (p+n)

Ex:

Isotopes

Sometimes the number of NEUTRONS can vary among atoms when they are in the form of an isotope.

Isotope Example: Carbon

**Important in Biology: radioactive tracers for kidney function

Practice: 11 Na Atomic # = _____ 23 p = ___ e- = ___

Atomic mass = _____

Element Identification Au Mercury Pb Mn Ar Neon Si Ag Al Lithium Mg Bromine Be Boron Cl He F Sodium K Ni

CompoundsCompounds

Most elements do not exist by themselves

Readily combine with other elements in a fixed ratio

A compound is a substance made up of atoms of two or more elements The proportion of

atoms are always fixed

Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound

Chemical Formulas - Chemical Formulas - ReviewReview

Subscript after a symbol tell the number of atoms of each element

H20 has 2 atoms of hydrogen & 1 atom of oxygen

Coefficients before a formula tell the number of molecules

3O2 represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen

Atoms in compounds are held together by chemical bonds. The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their outermost energy level - called valence electrons

Chemical Bonds

The chemical bonds that are important to Biology are covalent, ionic, and hydrogen bonds.

Covalent Bonds Formed by the sharing

one or more pairs of valence electrons of two atoms.

Strongest type of bond Impt to living things Found in Biomolecules Resulting substance is

stable, and is referred to as a molecule.

Ionic Bonds Formed between two atoms when one

atom loses an electron, and the other atom gains an electron.

This giving & receiving results in charged particles known as ions - they have an uneven # of protons and electrons.

Positive Ions - Cations “t” Atoms that lose

electrons are called cations and are “+”

Negative Ions - Anions Atoms that gain electrons are

called anions and are “-”

Hydrogen Bonds

Occurs when H+ (which is already bonded to an electronegative atom) is ATTRACTED to another electronegative atom.

Very weak bond Occurs between molecules, not

elements. Important in DNA. Weak attraction - does NOT involve

sharing or transferring of electrons.

DNA

Water