Unit 1 Lesson 1 The Chemistry of Biology

Proton, Electron, and Neutron Proton – positive particles that make up part of the nucleus of an atom Neutron – neutral particles that make up part of the nucleus of an atom Electron – negative particles that encircle the nucleus. Responsible for bonding The number of protons always equals the number of electrons in a neutral atom.

Periodic Table of Elements Atomic Number Standard Abbreviation Name Atomic Weight The number of protons and electrons The number of protons and neutrons

Atomic Weight 1 proton = 1 measure of weight 1 neutron = 1 measure of weight 1 electron = 0 measure of weight So… #protons + # neutrons = atomic weight To find the number of neutrons: Atomic weight – # protons (atomic #)= # neutrons

Drawing Diagrams Bohr Diagrams Hydrogen Carbon Oxygen Electron Dot Diagrams

Bonding Atoms try to fill their outside energy level (valence level). They do this by either gaining or giving away electrons. Atoms also do this by bonding with other atoms. Atoms that want to give away electrons will bond with atoms that want to gain electrons. Example: NaCl Na has 11 electrons, 1 in its valence shell and wants to give 1 away Cl has 17 electrons, 7 in its valence shell and wants to gain 1 electron

Types of Bonds 1. Ionic Bonds - actually give away the electron to its partner. 2. Covalent Bonds – the two atoms share the electrons. By sharing electrons both atoms will have full valence shells 3. Polar Covalent Bonds – atoms share the electrons unequally. One atom is much bigger that the other and holds the electron closer giving a slight negative charge to that end of the molecule 4. Hydrogen Bonds – polar covalent bonds create molecules that are mini magnets. The slight positive H of one molecule is attracted to the slightly negative O of another molecule. This creates a weak bond we call Hydrogen bonds

Examples of Bonds Ionic Bonds Covalent Bonds Polar Covalent Bonds Hydrogen Bonds

Energy There are two types of energy 1. Kinetic Energy – actually doing something 2. Potential Energy – the ability to do work Energy is stored in bonds (potential energy) when bonds are broken, energy is released (kinetic energy) when bonds are formed, energy is required.

Chemical Reactions Chemical reaction where atoms are joined together or split apart are represented by symbols in equation form. Example: If carbon is burned in the presence of oxygen, it will combine with oxygen to form carbon dioxide. C + O 2  CO 2 What this means is that 1 atom of carbon + 1 molecule of oxygen react or yield to form 1 molecule of CO 2.

Parts of a Chemical Equation 2H 2 + O 2  2H 2 O All the atoms on the left side of the arrow are called the reactants (they react together). The atoms on the right side of the arrow are the products (they are produced). The numbers in front of the letters represent the number of molecules, while the subscripts or smaller numbers are the base and to the right stand for the number of atoms in that particular molecule.