Chapter 2 Basic Chemistry Outline

Transcription

1 Chapter 2 Basic Chemistry Outline 1.0 COMPOSITION OF MATTER 1.1 Atom 1.2 Elements 1.21 Isotopes 1.22 Radioisotopes 1.3 Compounds 1.31 Compounds Formed by Ionic Bonding 1.32 Compounds Formed by Covalent Bonding 1.4 Chemical Reaction 2.0 ENERGY 2.1 Forms of Energy 2.2 Energy and Chemical Reactions 3.0 MIXTURES 3.1 Solution 3.2 Suspension 3.3 Colloids 3.4 Acids and Bases 2.41 Acids 2.42 Bases 2.43 ph Scale

2 Chapter 3 Basic Chemistry Lecture Notes 1.0 COMPOSITION OF MATTER -everything is made of matter -matter >> is anything that occupies space and has mass. 1.1 Atoms -atom is the fundamental unit of matter -all matter is made of atoms -atoms are composed of a nucleus, protons, neutrons, and electrons, -the nucleus is a very dense area located in the center of the atom -the nucleus contains the protons and neutrons -the proton has a positive charge + -the neutron has no charge (neutral) -the mass of an atom is concentrated in the nucleus -electron are located outside the nucleus in an electron cloud -electrons have a negative charge - -electrons in the outer most energy level of an atom determines how that atom will behave or react to other atoms 1.2 Elements -there are 92 naturally occurring elements in the world, all the rest are man made -element >>is a pure substance that can not be changed into a simpler substance by ordinary chemical treatment. -elements are made of atoms -the elements that are important in biology are: Name Symbol Type Atomic Number Mass Number # of valence e - # e - needed Hydrogen H gas Carbon C gas non metal Nitrogen N solid non metal Oxygen O gas non metal Sodium Na solid metal Potassium K solid metal Calcium Ca solid metal

3 -Atomic number >> the number of protons in an atom, -also gives the total number of electrons in an atom -mass number >> the sum of the number of protons and the number of neutrons -valence electrons >> the number of electrons in the outer most energy level of an atom -determines how an atom will react to other atoms or can say it determines the chemistry of an atom -atoms are unstable molecules, only the noble gases or inert gases are stable -in order to be stable an atom must have an completed energy level of 2 electron or 8 electrons 1.3 Compounds -a compound >> is two or more elements joined by chemical bonds -how elements combine to form compounds depends on the number and arrangement of the electrons in the outermost energy level called the valence orbital 1.31 Compounds Formed by Ionic Bonding -ionic bonds >>is the transfer of one or more electrons from one atom to another -atoms that give up electrons are called electron donors So they have a + charge -atoms that gain electrons are called electron acceptors So they have a - charge -ions >> atoms that carry positive or negative electric charges -atoms with opposite charges are attracted to each other so the atoms are held together -example: -sodium chloride NaCl Na has 1 valence electron and is willing to give it up in order to be stable +1 + Na or Na Cl has 7 valence electrons and needs 1 more to be stable -1 - Cl or Cl + - Na + Cl ----->> NaCl -magnesium iodide +2 Mg has 2 valence electrons Mg willing to give up 2 - Iodine has 7 valence electrons I needs Mg + I ----->>> MgI 2 must balance the equation +2 - Mg + 2I ----->> MgI 2 -ions are very important to living organisms: cell membrane function,

4 metabolic activity, neural function and more 1.32 Compounds formed by Covalent Bonding -molecule >>are two or more atoms of the same or different kind bonded together by covalent bonds -covalent bonding >> formed when two atoms share one or more pairs of electrons -elements that form covalent bonds the valence number of electrons also tells you how many bonds that element can form -there are three types of covalent bonds -single bond -double bonds -triple bonds -examples: -carbon dioxide -Carbons has 4 valence electrons and needs 4 more to be stable -carbon can form a total of 4 bonds -Oxygen has 6 valence electron and needs 2 more to be stable -oxygen can form a total of two bonds -in order to be stable the shared electrons must total either 2 or 8 -so carbon forms two double bonds to 2 oxygen C + O ---->> CO 2 must balance the equation C + 2O >>CO 2 -the structural formula >> show the arrangement of atoms in a molecule 1.4 Chemical Reactions -chemical reaction >> the process of breaking chemical bonds or forming new bonds -the chemical formula >> shows the number and kind of atom in each compound -examples: O 2 = 2 atoms of oxygen NaCl = 1 atoms of sodium and 1 atom of chlorine H O = 2 atoms of hydrogen and 1 atom of oxygen 2 -a number in front of the chemical formula tells you how many of that compound -examples: 2O 2 = 2 molecules of oxygen 4NaCl = 4 molecules of sodium chloride 6H2O = 6 molecules of water -molecule >> a group of atoms held by covalent bonds -also used when discussing a group of compounds of the same type

5 -chemical equation >> show how reactants change during a chemical reaction -to read a chemical equation C + 2O >> CO 2 Reactant Product -reactant >> the element or compound used in a reaction -product >> the element or compound produce from a reaction 2.0 Energy -living organisms use energy 2.1 Forms of Energy -energy >> the ability to do work -types of energy are: -light energy -heat energy -electrical energy -mechanical energy -chemical energy -law of conservation of energy >> state that energy can be neither created nor destroyed, but it can change forms -energy is classified as either potential or kinetic 2.11 Potential Energy -potential energy >> stored energy -in biology potential energy is locked in chemical bonds 2.12 Kinetic Energy -kinetic energy >> energy of motion -the kinetic energy of molecules determines its state: -solid >> molecules are packed tight and vibrate so has little kinetic energy -liquid >> molecules are not packed tight and can move more freely than a solid so have a greater kinetic energy -gas >> molecules are loosely packed and move freely so have the greatest amount of kinetic energy 2.2 Energy and Chemical Reactions -chemical reactions involve the use and transformation of energy -activation energy >> is the amount of energy required to start a chemical reaction -once a chemical reaction is started there is either a net release of energy or a net abortion of energy -exothermic reaction >> chemical reactions that have a net release of energy -can feel this release as heat -endothermic reactions >> chemical reactions that involve a net abortion of energy

6 -most reactions in the cell are endothermic -cells use and release energy -energy release to quickly can damage a cell -intermediary metabolism >> a series of chemical reaction by which energy is released slowly in controlled amounts that will not damage cells 3.0 MIXTURES -mixture >> is formed when two or more substances are blended together with no chemical change taking place -a mixture can be separated by physical means -the are different kinds of mixtures: solutions, suspensions, and colloids 3.1 Solution -solution >> a mixture in which one or more substances are uniformly distributed in another substance -solute >> is the substance being dissolved in a solution -solvent >> is the substance in which the solute was dissolved -concentration >> a measurement of the amount of solute dissolved in a fixed amount of solution -a solutions can become saturated -saturation >> is the point where no more solute will dissolve -a solution can cause ionic compounds to dissociate -dissociation >>is the separation of ion pairs -aqueous solutions >> a solution in which water is the solvent -are universally important to living organisms 3.2 Suspension -suspension >> a mixture in which particles spread through a liquid or a gas but settle out over time -the particles in a suspension are large than solute particles in a solution -blood is an example of a suspension 3.3 Colloids -also called colloidal suspensions -colloids >> mixtures in which particles do not settle out over time. -particles in a colloid are intermediate in size between particles in a solution and those in a suspension -colloids have two states of existence -sol state >> the liquid state of a colloid -gel state >> a Jell-O like state of a colloid that forms when the sol state is cooled -a colloid can change from a sol to a gel and from a gel to a sol 3.4 Acids and Bases -example: water H O 2

7 -hydrogen ion H + -hydroxide ion OH - -in neutral solution the number of hydrogen ion is equal To the number of hydroxide ions 2.41 Acids -an acid is a solution in which the number of hydrogen Ion is greater than the number of hydroxide ions 2.42 Bases -a base is a solution in which the number of hydroxide Ions is greater than the number of hydrogen ions 2.43 ph Scale -the ph scale measures the concentration of hydroxide Ions to the number of hydrogen ions