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Science Chemistry What is Chemistry? The science dealing with the structure and composition of substances, the changes in composition, and the mechanisms by which the changes occur. The study of matter and its interactions. What is matter? Anything that occupies space and has mass. Everything! Changes in composition What changes matter? Nature External force Most changes in matter accompany energy. What does chemistry and these changes in composition have to do with respiratory therapy? Definitions Atom The smallest unit of an element that can exist either alone or in combination with atoms of the same or different elements. Consist of protons, neutrons, and electrons. Element A substance that cannot be further decomposed by ordinary chemical means, a substance in which all the atoms have the same number of protons. Definitions Cont. Molecule The smallest chemical unit of a substance that is capable of stable existence. Molecules are made up of one or more atoms. If they contain more than one atom, the atoms can be the same (an oxygen molecule has two oxygen atoms) or different (a water molecule has two hydrogen atoms and one oxygen atom). Biological molecules, such as proteins and DNA, can be made up of many thousands of atoms. Definitions Cont. Compound A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. For example, dihydrogen monoxide (water) is a compound composed of two hydrogen atoms for every oxygen atom. The Atom The Atom Nucleus Protons Neutrons Electrons What is a neutral atom? Periodic table Symbols Atomic numbers (# of protons) Mass numbers (protons & neutrons) Rows (Periods) Columns (Groups or Families) Periodic table Metals Nonmetals Alkali Metal Elements Alkali Earth Elements Halogen Elements Noble Gas Elements Metalloids Transition Metal Elements Main Group Elements Electrons Excited state Ground state Energy levels Electron Configuration Quantum Atomic Model Bohr Model Lewis Electron Dot Model Electrons and Energy levels How many are there? How many electrons can they hold? How do the electrons fill the levels? Shell (energy levels 1-7) Sub-shell (s,p,d,f) Orbital Quantum Atomic Model Quantum Atomic Model Bohr Model Lewis Electron Dot Model Valence Electrons Combining capacity. Number given to an atom that indicates it’s tendency to loose or gain electrons in a chemical reaction. How many electrons are in an atom’s outer shell to be considered full? Periodic table short cuts Periods = # of shells each elements has Groups = # of electrons in outer shell (valence electrons) Stable atoms Atoms are said to be stable when their outer most shell is full. Which elements are stable on the periodic chart? Elements who do not have 8 electrons in their outer shell are constantly looking for a way to be stable. How do atoms fill their outer levels? Take electron(s) from another atom. Give electron(s) to another atom. Share electron(s) with another atom. Ions When atoms give or take electrons it changes their neutrality. Ion = an atom that has an electrical charge as a result of gaining or losing electrons. Cation = positively charges ion Anion = negatively charged ion. Types of bonds Ionic = a bond that has formed as a result of the atoms in the compound gaining/losing electrons. Covalent = a bond that has formed by the sharing of electrons between the various atoms in the compound. Hydrogen (Polar covalent) = occur when a Hydrogen atom is covalently bonded to a Nitrogen or Oxygen atom and is attracted to another Nitrogen or Oxygen atom. Isotopes Atoms of an element having the same chemical properties but different atomic weights. So if all atoms of a certain element have the same number of protons, what changes the atomic weight? Radioactive Isotopes Used in nuclear medicine Very unstable We manipulate their nuclear structure. They emit high energy radiation. They can be detected by instruments to evaluate the function of body parts. They do damage cells. Balancing Equations The substances that are starting material in a chemical reaction are REACTANTS. The substances produced as a result of the reaction are called PRODUCTS. Balancing a chemical equation consist of make your REACTANTS and Products equal. Balancing Equations Is this balanced? H + Cl² → HCl NO WAY! What would a balanced equation look like 2H + Cl² → 2HCl Balancing Equations Difference between a subscript and a coefficient. Subscript (N²) Can NEVER be changed! Coefficient (2N) Can always be changed! Coefficients need to be REDUCED aka SMALL! Organic & Inorganic Compounds Organic compounds are molecules that contain carbon to carbon bonds and/or carbon to hydrogen bonds. Inorganic compounds do not contain carbon. Inorganic compounds come principally from mineral sources of non-biological origin. Inorganic compounds often includes all metalcontaining compounds, even those found in living systems. Inorganic Compounds Types of inorganic compounds Major branches of inorganic compound groups include: Minerals, such as salt, asbestos, silicates, ... Metals and their alloys, like iron, copper, aluminum, brass, bronze, ... Compounds involving non-metallic elements, like silicon, phosphorus, chlorine, oxygen, for example water Metal complexes Inorganic Compounds What do you think is the most abundant inorganic substance in the human body? Wonderful Water! Absorbs and releases heat very slowly Requires a large amount of heat to change from a liquid to a gas. Serves as lubricant It participates in chemical reactions Hydrolysis Dehydration synthesis Is a great solvent! Solution A solution (salt water) is composed of a solvent (water) and a solute (salt). Organic Compounds Always contain carbon to carbon and/or carbon to hydrogen bonds. Most organic compounds are bound by covalent bonds containing hydrogen. 4 major organic compounds found in the body Carbohydrates Lipids Proteins Nucleic Acids Carbohydrates Carbohydrates are the bodies most readily available source of energy. The building blocks are monosaccharides. Carbohydrates are divided into 3 main groups based on size. Monosaccharides Disaccharides Polysaccharides Lipids Lipids protect and insulate the body. Lipids are an inefficient source of energy. Fats are lipids that are solid @ room temperature, and oils are lipids that are liquid @ room temperature. The building blocks are triglycerides, which are made up by one glycerol to three fatty acids. Lipids cont. There are three types of lipids found in the body. Triglycerides Saturated fat Monounsaturated Polyunsaturated Phospholipids Steroids Cholesterol Proteins Proteins have structural and functional properties in the body. Proteins cont. Structural Help form structures (e.g. collagen) Hold body tissues together Form a fibrous water-proof layer on skin (keratin) Functional Participate in chemical processes such as hormones, growth factors & cell membranes. Help reactions occur BUT are not reactants They are chemical catalyst called ENZYMES, which speed up reactions. Each enzyme has a shape that “fits” into the molecules involved in a reaction with the “Lock and Key Method”. Proteins cont. The building blocks are amino acids. When two or more amino acids combine the are bonded by peptide bonds. Nucleic Acids Nucleic acids are extremely large organic molecules containing carbon, hydrogen, oxygen, nitrogen, and phosphorus. The building blocks are nucleotides. There are two principle kinds: DNA (deoxyribonucleic acid) RNA (ribonucleic acid) DNA (deoxyribonucleic acid) Double helix The uprights of the ladder consist of alternating phosphate groups and the deoxyribose portions (sugar) of the nucleotides. The rungs on the ladder consist of alternating paired nitrogenous bases. Adenine paired with Thymine Cytosine paired with Guanine About 1000 rungs of DNA nucleotides comprise a gene. RNA (ribonucleic acid) Single strand RNA’s sugar ribose does not contain oxygen. RNA does not contain the nitrogenous base thymine, instead it contains Uracil. RNA has a specific role to perform with DNA in protein synthesis. Acids, Bases, and Salts…Oh my Acids, bases, and salts are considered inorganic compounds. Acids, Bases, and Salts…Oh my Acid typically water-soluble, when the acid disassociates (is dissolved) in water it produces an excess of hydrogen ions (H+) sour-tasting chemical compound In common usage an acid is any substance that, when dissolved in water, gives a solution a pH of less than 7. An acid reacts with a base in a neutralization reaction to form a salt. Acids, Bases, and Salts…Oh my Base typically water-soluble, when the base disassociates (is dissolved) in water it produces an excess of hydroxyl ions (OH-). In common usage a base is any substance that, when dissolved in water, gives a solution with a pH greater than 7. A base reacts with an acid in a neutralization reaction to form a salt. Acids, Bases, and Salts…Oh my Salt salt is a term used for ionic compounds composed of positively charged cations and negatively charged anions, so that the product is neutral and without a net charge. An example is the acid (chlorine) mixing with a base (sodium) which yields a salt (Na+Cl-). pH definition of pH is the negative logarithmic scale that measures the hydrogen ion concentration. The log is a base of 10. Meaning 6 is 10x different than 7, or 5 is 100x different than 7. pH scale The acidity or alkalinity (base) of a solution is measured on a scale of values called the pH scale. The values on the pH scale range from 0-14 0 indicates the most acidic (lowest) pH More H+ than OH- 14 indicates the most alkaline (highest) pH More OH- than H+ pH pH cont. A solution with a pH of 7.0 is neutral because it contains the same number of hydrogen ions (H+) as hydroxyl ions (OH-). Pure water has a pH of 7.0 The bodies neutral pH is slightly alkaline. Normal for the body is 7.35-7.45 pH cont. How do we get the pH of a substance? Is it measured or calculated? It is all in the term pH p = power of H = hydrogen ions It is calculated by the HendersonHassalbach equation. Henderson-Hassalbach equation pH= pK + log of bicarbonate/carbonic acid pH= pK + log (HCO3/H2CO3) pK= disassociation constant Changes depending on the acid We use 6.1 for H2CO3- Henderson-Hassalbach equation If the ratio of bicarb : carbonic acid is 20:1 it will yield a pH of 7.4 (normal) So what will a bicarb: carbonic ratio of 20:5 yield (acidic or alkaline)? What about 15:1.8 And 24:1.38 Henderson-Hassalbach equation As the HCO3:H2CO3 ratio increase from 20:1 to 25:1 the pH increases and becomes more alkaline. As the HCO3:H2CO3 ratio decreases from 20:1 to 15:1 the pH decreases and becomes more acidic. pH How do you think the body maintains the 20:1 ratio? It is maintained by three systems. Respiratory system Urinary system (metabolic) Chemical buffer system This is a CONSTANT process! Respiratory system The respiratory system maintains the acid-base balance by increasing or decreasing your respiratory rate. When we breathe out what gas are we exhaling? Is that an acid or a base? Respiratory system So if we increase our rate we are getting rid of acid, or causing our blood to be more alkaline. If we decrease our rate we are holding onto acid, or causing our blood to be more acidic. Urinary system (metabolic) We can maintain acid-base balance by urinating more base or holding onto it. If a patients urine is very acidic their body is holding onto the HCO3, making the blood more alkaline. If a patients urine is very alkaline their body is getting rid of the HCO3, making the blood more acidic. Chemical Buffer Systems Strong Acid-disassociates completely to H+ ions. Weak Acid-partially disassociates to H+ ions. Strong Base-disassociates completely to OH- ions. Weak Base-partially disassociates to OH- ions. Chemical Buffer Systems Buffer A chemical substance that prevents a sharp change in the pH of a fluid when an acid or base is added to it. Buffer pairs Chemical substances that are paired to buffer both acids and bases. Common example is NaHCO3 & H2CO3 NaHCO3 & H2CO3 buffer pair If HCl, a very strong acid, was exposed to your bloodstream without being buffered it would cause harm. When HCl walks up to the NaHCO3 & H2CO3 buffer pair who will it choose to bind with? NaHCO3 OR H2CO3 NaHCO3 & H2CO3 buffer pair NaHCO3! When HCl (strong acid) pairs with NaHCO3(buffer) the product is NaCl (salt) & H2CO3(weak acid). NaHCO3 & H2CO3 buffer pair On the other hand if a strong base, such as NaOH, was added to the NaHCO3 & H2CO3 buffer pair which buffer would it pick? NaHCO3 OR H2CO3 NaHCO3 & H2CO3 buffer pair H2CO3! When NaOH (strong base) pairs with H2CO3(buffer) the product is H2O (water) & NaHCO3(weak base). 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