Basic Chemistry Review

Matter 1. Matter refers to anything that takes up space and has mass 1. Matter refers to anything that takes up space and has mass 2. All matter (living and nonliving) is composed of basic elements 2. All matter (living and nonliving) is composed of basic elements a. Elements cannot be broken down to substances with different chemical or physical properties a. Elements cannot be broken down to substances with different chemical or physical properties b. There are 92 naturally occurring elements b. There are 92 naturally occurring elements c. Six elements (C, H, N, O, P, S) make up 98% of most organisms c. Six elements (C, H, N, O, P, S) make up 98% of most organisms

Elements Contain Atoms 1. Chemical and physical properties of atoms depend on the subatomic particles: 1. Chemical and physical properties of atoms depend on the subatomic particles: a. Different atoms contain specific numbers of protons, neutrons, and electrons a. Different atoms contain specific numbers of protons, neutrons, and electrons b. Protons (+ charge) and neutrons (neutral charge) are in nucleus of atoms; electrons (- charge) move around nucleus b. Protons (+ charge) and neutrons (neutral charge) are in nucleus of atoms; electrons (- charge) move around nucleus 2. Isotopes = atoms with the same number of protons but differ in number of neutrons; e.g., a carbon atom has six protons but may have more or less than usual six neutrons 2. Isotopes = atoms with the same number of protons but differ in number of neutrons; e.g., a carbon atom has six protons but may have more or less than usual six neutrons a. Isotopes used to determine age of fossils and in medical diagnostic and treatment procedures a. Isotopes used to determine age of fossils and in medical diagnostic and treatment procedures

Chemical Properties of Atoms 1. Since protons are positively charged & electrons are negatively charged they are attracted to each other 1. Since protons are positively charged & electrons are negatively charged they are attracted to each other 2. Arrangement of atom's electrons is determined by total number of electrons and electron shell they occupy 2. Arrangement of atom's electrons is determined by total number of electrons and electron shell they occupy a. Energy = capacity to do work a. Energy = capacity to do work b. Electrons with least amount of potential energy are located in shell closest to nucleus; electrons having more potential energy are located in shells farther from nucleus b. Electrons with least amount of potential energy are located in shell closest to nucleus; electrons having more potential energy are located in shells farther from nucleus

c. How atoms react with one another is dependent upon number of electrons in outer shell c. How atoms react with one another is dependent upon number of electrons in outer shell 1) Atoms with filled outer shells do not react with other atoms 1) Atoms with filled outer shells do not react with other atoms 2) In atom with one shell, outer shell is filled when it contains two electrons 2) In atom with one shell, outer shell is filled when it contains two electrons 3) For atoms with more than one shell, the outer shell is stable when it contains eight electrons 3) For atoms with more than one shell, the outer shell is stable when it contains eight electrons 4) Atoms with unfilled outer shells react with other atoms so each has stable outer shell 4) Atoms with unfilled outer shells react with other atoms so each has stable outer shell 5) Atoms can give up, accept, or share electrons in order to have a stable outer shell 5) Atoms can give up, accept, or share electrons in order to have a stable outer shell

Types of Bonds 1. Covalent bond - involves sharing of electron(s). Electrons possess energy; bonds that exist between atoms in molecules contain energy. 1. Covalent bond - involves sharing of electron(s). Electrons possess energy; bonds that exist between atoms in molecules contain energy. Sharing of a pair of electrons creates a single bond represented by single dash, e.g. water H 2 O is made of two single bonds H-O- H. Sharing two pairs of electrons is represented by two dashes, C=C Sharing of a pair of electrons creates a single bond represented by single dash, e.g. water H 2 O is made of two single bonds H-O- H. Sharing two pairs of electrons is represented by two dashes, C=C Know the number of covalent bonds each of the six most important elements can form. Know the number of covalent bonds each of the six most important elements can form. Element# of covalent bonds:Hydrogen-1, Oxygen-2, Nitrogen- 3, Carbon-4, Phosphorous-5, Sulfur-2 Element# of covalent bonds:Hydrogen-1, Oxygen-2, Nitrogen- 3, Carbon-4, Phosphorous-5, Sulfur-2

Types of bonds 2. Ionic bond - electrons are transferred from one atom to another, e.g. salt NaCl 2. Ionic bond - electrons are transferred from one atom to another, e.g. salt NaCl 3. Hydrogen bond - weak attractive force between slightly positive hydrogen atom of one molecule and slightly negative atom in another or the same molecule 3. Hydrogen bond - weak attractive force between slightly positive hydrogen atom of one molecule and slightly negative atom in another or the same molecule a. E.X.: in a water molecule the electrons spend more time orbiting the oxygen than the hydrogens, therefore the oxygen becomes slightly negative and the two hydrogens become slightly positive a. E.X.: in a water molecule the electrons spend more time orbiting the oxygen than the hydrogens, therefore the oxygen becomes slightly negative and the two hydrogens become slightly positive b. Such polar molecules attract each other like magnets b. Such polar molecules attract each other like magnets

Atoms form Molecules and Compounds A. Molecules = two or more atoms of same or different elements bonded together (e.g., O 2 ) A. Molecules = two or more atoms of same or different elements bonded together (e.g., O 2 ) B. Compound = molecule of two or more different elements bonded together (e.g., H 2 O) B. Compound = molecule of two or more different elements bonded together (e.g., H 2 O)

Acids and Bases 1. Water dissociates - has a tendency to spontaneously break into hydrogen and hydroxide ions: 1. Water dissociates - has a tendency to spontaneously break into hydrogen and hydroxide ions: H > H+ (hydrogen) + OH- (hydroxide) H > H+ (hydrogen) + OH- (hydroxide) 2. Acid molecules dissociate in water, releasing hydrogen ions (H+) ions: 2. Acid molecules dissociate in water, releasing hydrogen ions (H+) ions: Hydrochloric acid (HCl) is a strong acid: HCl ---> H+ + Cl – Hydrochloric acid (HCl) is a strong acid: HCl ---> H+ + Cl – 3. Bases are molecules that take up hydrogen ions or release hydroxide ions: 3. Bases are molecules that take up hydrogen ions or release hydroxide ions: Sodium hydroxide (NaOH) is a strong base: NaOH ---> Na+ + OH- Sodium hydroxide (NaOH) is a strong base: NaOH ---> Na+ + OH-

4. pH scale, which ranges from 0 to 14, is used to indicate the strength of acids and bases 4. pH scale, which ranges from 0 to 14, is used to indicate the strength of acids and bases a. pH = a measure of hydrogen (H+) ion concentration in a solution a. pH = a measure of hydrogen (H+) ion concentration in a solution b. Low pH value indicates a high concentration of H+ ions (acids) b. Low pH value indicates a high concentration of H+ ions (acids) c. High pH value indicates a low concentration of H+ ions (bases) c. High pH value indicates a low concentration of H+ ions (bases) d. pH value of 7 is neutral, i.e. the solution has an equal concentration of H+ and OH- ions d. pH value of 7 is neutral, i.e. the solution has an equal concentration of H+ and OH- ions e. pH scale is logarithmic, i.e. a ten fold difference for each number e. pH scale is logarithmic, i.e. a ten fold difference for each number E.X.: pH 4 is 10 times more acidic than 5, and 100 times more acidic than 6 E.X.: pH 4 is 10 times more acidic than 5, and 100 times more acidic than 6

5. Buffers keep pH steady and within normal limits in living organisms, e.g. blood pH is Buffers keep pH steady and within normal limits in living organisms, e.g. blood pH is 7.4 a. Buffers stabilize pH of a solution by taking up excess hydrogen or hydroxide ions a. Buffers stabilize pH of a solution by taking up excess hydrogen or hydroxide ions b. Carbonic acid helps keep blood pH within normal limits b. Carbonic acid helps keep blood pH within normal limits

Organic vs Inorganic Organic Organic Those chemicals that contain BOTH carbon and hydrogen atoms Those chemicals that contain BOTH carbon and hydrogen atoms Carbohydrates, lipids, proteins, nucleic acids Carbohydrates, lipids, proteins, nucleic acids  Inorganic  Water, oxygen, carbon dioxide, inorganic salts  Dissolve in water or react with water to release ions - electrolytes

Water A. Life evolved in water A. Life evolved in water All living things are 70-90% water All living things are 70-90% water Because water is a polar molecule, water molecules are hydrogen bonded to each other Because water is a polar molecule, water molecules are hydrogen bonded to each other a. hydrophilic molecules - polar molecules attracted to water molecules a. hydrophilic molecules - polar molecules attracted to water molecules b. hydrophobic molecules - non-polar molecules repelled by water b. hydrophobic molecules - non-polar molecules repelled by water

Properties of Water 1. Water resists temperature changes because hydrogen bonds between water molecules require a large amount of heat to break 1. Water resists temperature changes because hydrogen bonds between water molecules require a large amount of heat to break a. Calorie = amount of heat energy required to raise temperature of one gram of water 1° C. This is about twice that of other liquids a. Calorie = amount of heat energy required to raise temperature of one gram of water 1° C. This is about twice that of other liquids b. Water has a high heat of vaporization - takes 540 calories to change water to a gas b. Water has a high heat of vaporization - takes 540 calories to change water to a gas c. When animals sweat, evaporation of the sweat takes away body heat, thus cooling the animal c. When animals sweat, evaporation of the sweat takes away body heat, thus cooling the animal d. Because water resists temperature changes the earth's surface temperature is moderate and organisms are protected from rapid temperature changes, this helps them maintain normal temperatures d. Because water resists temperature changes the earth's surface temperature is moderate and organisms are protected from rapid temperature changes, this helps them maintain normal temperatures

2. Water is universal solvent, facilitates chemical reactions both outside of and within living systems 2. Water is universal solvent, facilitates chemical reactions both outside of and within living systems a. Water is a universal solvent because it dissolves a great number of solutes a. Water is a universal solvent because it dissolves a great number of solutes b. Important because living organisms get and transport most of needed chemicals in water or water based solutions b. Important because living organisms get and transport most of needed chemicals in water or water based solutions

3. Water molecules are cohesive and adhesive 3. Water molecules are cohesive and adhesive Cohesion - like molecules cling to each other Cohesion - like molecules cling to each other Adhesion - ability to adhere to polar surfaces; water molecules have positive, negative poles. Adhesion - ability to adhere to polar surfaces; water molecules have positive, negative poles. Capillarity - the tendency for a liquid to move upward against pull of gravity through a narrow space, e.g. water rises up tree from roots to leaves through small tubes Capillarity - the tendency for a liquid to move upward against pull of gravity through a narrow space, e.g. water rises up tree from roots to leaves through small tubes 1) Adhesion of water to walls of vessels prevents water column from breaking apart 1) Adhesion of water to walls of vessels prevents water column from breaking apart 2) Cohesion allows evaporation from leaves to pull water column from roots 2) Cohesion allows evaporation from leaves to pull water column from roots

4. Frozen water is less dense than liquid water 4. Frozen water is less dense than liquid water a. Below 4° C, hydrogen bonding becomes more rigid but open, causing expansion a. Below 4° C, hydrogen bonding becomes more rigid but open, causing expansion b. Because ice is less dense, it floats; therefore, bodies of water freeze from the top down b. Because ice is less dense, it floats; therefore, bodies of water freeze from the top down c. This means that ice floats and the bottoms of lakes and oceans are still available for life and also insulated during cold weather c. This means that ice floats and the bottoms of lakes and oceans are still available for life and also insulated during cold weather

Oxygen Molecules of oxygen enter the body through the respiratory organs (we breathe) and then transported throughout the body by blood and red blood cells (by diffusion) Molecules of oxygen enter the body through the respiratory organs (we breathe) and then transported throughout the body by blood and red blood cells (by diffusion) Cellular organelles use oxygen to release energy from the sugar glucose and other nutrients Cellular organelles use oxygen to release energy from the sugar glucose and other nutrients The released energy drives the cell’s metabolic reactions The released energy drives the cell’s metabolic reactions