BASIC 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- C 6 H 12 O 6 water - H 2 O salt - NaCl

Composition of Matter Matter - Everything in universe is composed of matter Matter is anything that occupies space or has mass Mass – quantity of matter an object has Weight – pull of gravity on an object

Elements 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)

Atoms 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 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 Neutrons Are neutral Located in the nucleus of an atom

The 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 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 # = _____ 23p = ___ e - = ___ Atomic mass = _____

Element Identification Au MercuryPb Mn Ar NeonSi Ag Al LithiumMg Bromine Be BoronCl He F SodiumK Ni

Compounds 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 - Review Subscript after a symbol tell the number of atoms of each element H 2 0 has 2 atoms of hydrogen & 1 atom of oxygen Coefficients before a formula tell the number of molecules 3O 2 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