CH 101 1st Edition Lecture 3 Outline of Last Lecture I Converting from Grams to Moles to Grams II The Difference between O and O2 III How to Determine the Limiting Reagent in a Chemical Reaction A The Drawing it Out Method B The Math Method IV The Scientific Method A Dalton s Atomic Theory Defining Matter and Energy V Outline of Current Lecture I Coulomb s Laws of Force and Energy II Attracting and Repelling Charges A High Energy versus Low Energy III Subatomic Particles A Isotopes IV Understanding the Periodic Table Current Lecture I II Coulomb s Laws of Force and Energy Coulomb s Law of Force The charge of particle 1 q1 times charge of particle 2 q2 times Coulomb s constant k 8 98x109 over the distance m squared times the dielectric constant e However Coulomb s constant and the dielectric constant are rarely used so Coulomb s law of force is written as F q1q2 r2 According to Coulomb s law of force a force can become stronger if the numerator is increased meaning that the charge of the particles becomes greater or the denominator is decreased meaning that the distance becomes smaller This tells us that a strong force of attraction or repulsion comes from a high charge of the particles and a short distance between them Coulomb s Law of Energy This law has the same equation as Coulomb s Law of Force except the distance isn t squared F q1q2 r Attracting and Repelling Charges These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Opposite charges attract and similar charges repel each other This can be shown through magnets where the north and south poles will hold together but the north pole will not attach to another north pole A High Energy versus Low Energy When charges attract the spontaneous reaction would be that they come together and decrease the distance r between them The energy decreases in a spontaneous reaction therefore attractive forces decrease in energy This tells us that repelling forces must increase in energy A graph of an attractive force versus a repelling force would look like this Repelling Forces Attractive Forces To determine the energy of a molecule use Coulomb s Law of Energy Ex Determine which molecule has the highest energy the most positive energy Molecule 1 q1 2 q2 2 r 1 m Molecule 2 q1 2 q2 3 r 2 m Molecule 3 q1 1 q2 2 r 1 m Now plug these numbers into E q1q2 r Molecule 1 2 2 1 4 Molecule 2 2 3 2 3 Molecule 2 is a repelling force and has the highest energy Molecule 3 1 2 1 2 To determine the force of a molecule use Coulomb s Law of Force This will determine the molecule with the most repulsive force and the molecule with the most attractive force Ex Determine the molecule with the most attractive force the most negative number Molecule 1 q1 2 q2 2 r 1 m Molecule 2 q1 2 q2 3 r 2 m Molecule 3 q1 1 q2 2 r 1 m Now plug these numbers into F q1q2 r2 Molecule 1 2 2 12 4 Molecule 1 has the most attractive force Molecule 2 2 3 22 1 5 Molecule 3 III 1 2 12 2 Subatomic Particles Electron Negatively charged 1 has a mass of 0 0005 amu The number of electrons are equal to the amount of protons unless the molecule is a cation positively charged or an anion negatively charged Cations and anions are both ions of an atom which is created when the number of electrons is not the same as the number of protons Proton Positively charged 1 has a mass of 1 0078 amu Neutron Does not have a charge 0 has a mass of 1 0087 amu Atomic Mass The atomic mass is the sum of the number of protons and neutrons in an element and is the average mass of one mole of that element The atomic mass of oxygen is 16 and there are 8 protons this means that there are 8 neutrons because 16 8 8 Atomic number The atomic number is the number of protons in an element The amount of protons in an element will never change only the number of electrons and neutrons can change The atomic number is always smaller than the atomic mass this is an easy way to know the difference between the two on the periodic table A Isotopes Isotopes are the different masses of an atom of the same element based on the change in the number of neutrons The element iron has four isotopes with the atomic mass of 54 56 57 and 58 To find the number of neutrons in each isotope subtract each by the number of protons in an iron atom which is 26 IV Understanding the Periodic Table Group Groups also called a family on the periodic table are the vertical columns Groups are similar in composition The elements F fluorine and I Iodine are more similar than elements F and O because F and I are in the same family Period Periods on the periodic table are the horizontal rows Potassium is in the same period as Bromine Metals Metals are located in the center and the left side of the periodic table All alkali and alkaline earth metals are metals but not H hydrogen even though it is on the left side of the periodic table Metals are hard and shiny and are typically easy to manipulate Nonmetals Nonmetals are located on the right side of the periodic table They are separated from the metals by the diagonal metalloid elements Halogens and noble gasses are nonmetals Nonmetals are generally gasses such as hydrogen oxygen and helium but there are some solids that are nonmetals like carbon and sulfur Metalloids Metalloids are located on the right hand side of the periodic table between the metals and the nonmetals all of the metalloids include B Si Ge As Sb Te and Po The properties of a metalloid are a mixture between metals and nonmetals Alkali metals Belong in group one in the periodic table the alkali metals are Li Na K Rb Cs and Fr These metals are highly reactive because they only have one electron in their outer shell you know this because they are in row 1 Main Group Elements The main group elements are composed of the elements in groups 1 2 13 14 15 16 17 and 18 This is basically all of the elements except the transition metals The main group of elements helps us to understand how many electron are in their outer shells because there is 1 electron in group one s outer shell 2 in group two s outer shell 3 in group thirteen s outer shell 4 in group fourteen s outer shell and so on Transition Elements These elements are in the center of the periodic table and are under the general category of metals but because they …